Fuel problem. Opinions??

[ShaneC]

G'day all,

I have had an ongoing issue with a fuel tank in my boat. This has been going on for a fair while, albeit intermittently, but it has finally done my head in and I am going to do something about it and just want to put it out there to see if anyone can think of something less drastic or think of a different reason for the symptoms I am experiencing. Also, I am not going down the path of 'warranty' or 'fit for purpose' talks, I am at a stage that I have had enough and will just fix it myself as I dont want to draw it out and am not in the game of slagging people who installed it.

Approximately 18 months ago I had one of my fuel tanks replaced as I had an electrolysis issue that caused a small leak. Rather than muck around repairing the tank, I opted to replace it as the effort involved in cutting the sealed deck, removal of the tank and refit/ relay of the deck seemed too much to replace with anything but a brand new tank.

From the outset I had an issue. From time to time the motor being fed from the new tank starves of fuel periodically, getting worse and worse until such a time I turn that motor off and get home on the other one. At the start I replaced all filters, fuel lines and fittings from that tank and found a small part of the line that had minor delamination. Bingo!! Problem solved!! But it wasn't to be..... after a period of time ( a couple of months later and any number of tanks of fuel) it happened again. Followed the same process, problem disappeared for a while. At this stage I changed the tanks over with a cross feed and had my starboard motor running off the port tank, and vice versa. I did this to work out if it may have been an infrequent motor issue, basically if I could get the other motor to behave the same way, I would know it was tank related. After a while I gave up on it, I was sick of the fuel lines on the deck, but nothing happened until I changed them back then the original problem came back, and after changing them over again I finally made the other motor starve of fuel so knew it was the tank and not the motor.

Now when the problem occurs (as I stated there can be months between occurences), if it happens once, it will invariably get worse and worse and it doesnt take long before that motor is useless. In between occurences the motor runs fine with no hassles. Last time it happened off the Breaksea, we were ready for it, waited until it was unworkable, then cut the fuel line and ran it out of jerries for the trip home. We went from Roonies to Urangan with out any hassles at all running out of the jerries.

This is what I believe to be the problem. I think there is something non dissolvable floating around in the tank. How it got there, or was left there, is anyones guess but I think it floats around for a random length of time, and eventually gets caught in the pick up, and once it is there, it stays there until the boat gets refuelled or it moves around while travelling or something, boat goes good for a length of time until it finds its way back to the pick up.

The breathers are clear and not blocked. There is no air getting into the system, I have checked but not replaced the lines laid into the hull channel, but I would think that if it was entraining air the problem would be more ongoing and no way you could go months at a time without it arising again. Its not the motor, as I said we can make both motors do the same thing when running off that tank and it will run perfectly out of a separate jerry after being unusable when the problem starts.

This is what I am going to do. I have a guy with a big petrol sucky thing coming around next week. I have made up a spear that can go to the bottom of the tank thats much bigger than the pick up to quickly drain the tank and hopefully pull something out of it. He is happy to drain it and fill it up a few times in the hope of dislodging something and we will run it through a sieve so we know if we catch it. If that doesnt work I am going to drain the tank, 'defume' it so to speak and cut through the deck and cut a hole in the tank to physically inspect it. This is obviously a worst case scenario, as it does bring with it a job to fix the boat and some risk (although I will mitigate that). I will then reseal the tank with a sender unit. Should I find something in the tank I will remove it, but with the size of the baffles I would have to be lucky do cut in the right compartment of the tank, if I find nothing, I plan to drill holes in the pick up, that way if the object does block the pick up, fuel can still be drawn through the holes.

Sorry for the long winded post, but in this one I feel all the information is relevant.

Am I right in suspecting something is in the tank?? If not, what do you think is the problem??
Are my methods for addressing the problem right, wrong, or plain silly? I am very open to any ideas at this stage.

It is a very random problem, and very annoying. It can happen on a full tank, half full tank or a near empty tank. There is no vacuum lock or anything involved, if there was I would assume there would be a hissing noise when I crack the fuel cap when the problem happens, also I have checked and rechecked the breather and it is fine. It is a 340 litre tank, but I dont think this is a problem to do with size.

Any ideas, solutions or general musings to help fix this issue would be greatly appreciated before I wield my holesaw.

Cheers.

[littlejim]

Maybe not relevant, but on my smaller boat I got a related problem where my donk would die at high revs but was OK at low speeds.
In my case turned out that when I fitted the fuel filter I made one hose too long and it kinked under way.
Enough fuel got past the kink for low speed work but not for full bore.
Hope you sort it out.

My other fuel problems were caused by the "servicer" not changing the fuel filter under the cowl, that ruined my original motor.

[wardy40]

Shane, to prove if something is blocking the fuel pick up, try and stick some stainless wire (Tig rod etc) so that it is protruding into the tank and reconnect your fuel line with the wire still inside. Make sure the wire has enough length to not come back out up inside the pick up pipe and negate the test. This should prevent anything from completely blocking off the fuel pick up whilst testing.

[PROS]

one of those flexible inspection cameras might be able to help to look inside the tank?

[ShaneC]

Hi littlejim, that thought crossed my mind too so I went and bought some 90 degree elbows and put them in the lines instead of having any curves. Wardy I like that idea, that could even potentially work in as a more permanent solution as long as the object is not a rag or something that can cover the lot. I like the way you think, its not something I thought of. I still have the old tank thats exactly the same so can work everything out using it and get rid of it as scrap...

[ShaneC]

Hi PROS, we thought of that too and its an option once the tank is empty. Nobody could tell me if they are intrinsically safe but I would assume they are since they use them in sewers. Just not sure if one that was long enough would fit between the baffles and the sides of the tank but its certainly an option.

[wardy40]

Shane I would be careful too with the I.S issue. the only one i'd use would be with a fibre optic extension. But it would be the only way to know for sure.

[Dan5]

Mate it might be more trouble than it's worth but see if someone in your are will do a Bore a scope inspection for you.........They are I.S as we use the offshore frequently to do valve and pipework inspection........Maybe a longshot but it could be worth a try.

Dan

[Fed]

Is the primer bulb getting sucked flat?

[ShaneC]

Yes it is mate. But I have replaced it five times in an effort to make sure the solution is not the most simple one. I did get a dud primer bulb, thought I had it sussed, but it happened again

[perko]

Can you blow back through the line and see if there is any restriction?

[Darren J]

G'day all,

I have checked but not replaced the lines laid into the hull channel,

Cheers.
Shane,
The dramas live on!!.

When you say checked the lines laid in the hull, what exactly do you mean? Can you connect a new line to the tank itself or is there absolutely no access. If these are original lines, are you sure that is not where the problem remains, like if they were slowly delaminating internally or something.

When it does happen, what do you do to make the problem go away? Just give it time before the next trip out?? Have you ever solved it in the water, as in after some time, it has run ok later in the same trip, without redeveloping the problem?
When you simulated the problem on the other motor how much of the problem tank setup and plumbing remained in use, (ie. just the tank and the original line in the hull, or was it fed form that complete system, filter etc)?
Exactly which bits remained in use when connected to the opposite motor?

If it was an airlock, you would expect it to be solved (temporarily) as soon as you crack the filler, so you would have to assume not that issue and thus nothing related to the breather.

You never had these issues before you changed to the new tank did you (from what I recalled)?

[Fed]

A flat bulb indicates a fuel restriction so you are on the right track.

[ShaneC]

Hey Perko. Yep can blow back into the tank with a lung full of air and blow bubbles with no hassles. Darren, mate I have pressurised the tank without any air leak so I am confident thats not it. When we cross fed the tanks.. my set up goes from tank to filter to motor. I made up some cross feeds (I actually had them in case a motor went on the last day of a big trip so we could draw fuel from both tanks in an emergency) that gave fuel the same way just on the other motor. Its not a dangerous problem now that I know how to get around it but I feel its something I certainly dont need, especially if I make the effort to drive to Agnes or Bowen and it happens on the way out......

[ShaneC]

And the inlaid fuel lines are not rubber

[Darren J]

I was just thinking that the only parts not replaced or bi-passed from your tests is the tank itself and that first internal line, so it must be either of those. It would be good to eliminate that line as a possibility before cutting floors or tanks.

I assume you have bi-passed the fuel filter/head etc. It would be disappointing to find there was something solid (like a dislodged piece of the old fuel lining that was breaking up) that is jammed in the head at a bend or something. Possibly sufficient to restrict flow from time to time if it moves. But maybe its lodged sufficient that it does not clear through.

I guess, given it is intermittent and seems to clear itself for no obvious reason, you would want to be sure you really have eliminated all possibilities. For example, when it ran fine on the jerries, were you using any part of the existing system? If you did, you would assume that part of the system is ok. But it may not be the case. By the time you connected in the jerries, it is possible the original system may have come good again if you simply reconnected it, it may have then got you home also without trouble. I guess just because it all ran on them doesn't necessarily prove the problem was back in the system from there.

[gofishin]

Is the primer bulb getting sucked flat? Yes, first question that comes to mind.

For the times when you had to come home on one donk, did the motor just die/not perform, or did it come good and die repeatedly?

Does the new tank have a sender unit installed? If so, swing arm or vertical/plunger type?
Cheers
Brendon
P.S. Drilling holes in the pickup tube will reduce the tank's useable volume, as it will suck air/vapour once the fuel level drops to/reaches the highest hole!

However , if you drill a few holes say 6 - 10mm higher than the bottom of the pickup tube, this will tell you if it is a hard flat object or a flexible plastic/fabric etc that is causing the blockage. I say a few because you want the total area of the holes to be equal to (or within 85% of) the pickup tube I/D.

Edit; sorry, started typing a while ago before a lot more replies came about.


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[tunaticer]

Sounds to me like there is a large fish scale in the tank.
Old payback method that usually results in them selling the car/boat. Anyone got the shits with you?

The fish scale drifts about in the tank and eventually goes near the pickup and seals it off completely at a totally random timeline.

What diameter is your pickup line?

OMC tanks have a fine mesh end about 35mm long to a 6mm pickup line.
Possible that it might be large enough to feed your engines and possible you might be able to push it through the pickup line and into the tank. It will solve the problem if it is a fish scale.

It is not a piece of rag if the primer bulb sucks flat.

[Fed]

I used to get salt clogging the mesh in the breathers that was sort of intermittent and would often disappear by itself, could have simply dropped off while trailering.
It wasn't a 100% clog just a restriction but enough to flatten the primer bulbs at speed, I'm guessing you've looked up their bums like a CSI. You hinted around checking the breather but did you actually try it with the fuel cap released?

Had a car that did the same thing and it turned out to be a rubber hose spout floating around inside the tank & also breaking up, it looked like an old fashioned rubber fuel hose spout from a servo pump. I used to have to disconnect at the fuel pump & blow back into the tank then be good to go for a day or a month. Car was a fibreglass kit car and the tank was built in under the back deck so I was reluctant to cut the back deck out... it was like winning lotto when I found it.

[ShaneC]

The tank has no sender unit, I use an old fashioned dipstick to gauge the fuel level. Fed I have pretty much eliminated the breather, it is protected by a shroud to stop salt getting in, but the breather as a whole was not changed when the tanks were and I never had the drama prior to the new tank. Tunaticer, mate plenty of people have the shits with me at any given time but I am not sure any of them would stoop to those levels. That scenario has crossed my mind many times and cant be eliminated outright, but its still got me buggered what the object is. I am interested that you say a piece of rag would not suck the primer flat though. Do you think enough fuel could get through a rag to run the motor?? That being the case it makes Wardys idea of a piece of stainless wire through the pick up a very feasible one to give a go.

[rtp1984]

Hey Shane.
Where do you fill?
through the deck I assume if you check fuel level with a stick.

Could you set up a temperary pick up through the filler cap.
This would then draw your suspect to it, you would nearly be able to unscrew the cap and pull the object out still sucked on the end of the pick up, or at least be able to look through the filler cap and see what it is

[ShaneC]

I fill up through a filler in the gunnel mate. The idea of drilling a hole through my filler cap and making a pick up that was much larger than what I have did cross my mind thinking I may be able to pick the object up so it would remain in my filter. Sounds good in theory but I discounted it as unpractical.

[Darren J]

If you do resort to cutting the deck/tank, maybe fit a second pick up, and run it as well as the original, as in draw from both pick ups. They can't both get blocked together, if there is some physical separation between them.

Would be interesting to run the boat as normal, when the problem next occurs, undo a fuel fitting, blow back into the tank (to dislodge the suspect blockage), connect and see if the problem immediately clears and fails to return.

[Bremic]

My parents had similar problems with their car. Went on for several years, would happen every couple of days and then no problem for months. The old man tried everything he could think of until he eventually pulled the fuel tank out. He found a bit of wax paper in the fuel tank, something like a bubblegum wrapper. After that, no more problems. Would have thought the wax paper would have broke down in the petrol, but there you go.

[trymyluck]

My parents had similar problems with their car. Went on for several years, would happen every couple of days and then no problem for months. The old man tried everything he could think of until he eventually pulled the fuel tank out. He found a bit of wax paper in the fuel tank, something like a bubblegum wrapper. After that, no more problems. Would have thought the wax paper would have broke down in the petrol, but there you go.

Heard of people using a tallyho paper in the fuel tank as payback for whatever reason. Apparently they don't breakdown and float around until they get sucked to the pickup.

Mark

[ShaneC]

I would suggest that would be a great get back. But the problem started as soon as the new tank was fitted so I would not think the bloke I paid $5k to do it would hold a grudge.

[John Buoy]

Silly question I know but is bulb is fitted with correct direction of flow Shane ?
Can you fit a clear filter close to tank as this will show you whether fuel is flowing.
Mostly though it does sound like a tank blockage !

[scottar]

If you do end up putting a hole into the tank as an access, why not put it directly over or as near as possible to the pick up - that way it should be an easy sighting/retrieval of the blockage if the issue re-occurs. I would try the bit of wire and the bore scope first.

[gofishin]

The tank has no sender unit, I use an old fashioned dipstick to gauge the fuel level ... Well that rules out this as a source. Why I asked was some years ago there were two types of faults with typical plunger senders causing this exact problem!

I have also seen this problem caused by a bit of careless removal of masking tape on the tank pipe risers in a cat. i.e. to stop crap entering the tank while the floor (and tank risers) was glassed up/over. Then when the guy fitted the hoses, he was careless and lazy!

It could be anything, but I would try a few things before getting the pneumatic tools out for the tank.

A simple schematic of this tanks fuel system, showing all line components and bits that have, and the hose which has not been replaced might help people get their head around the problem a bit better, and prompt a few more suggestions.

How many baffles/chambers does the new tank have? I guess at least 2 baffles. Where is the filler in relation to the pickup?

Does the problem occur at all tank levels, or more prevalent when 1/2 full or nearly empty etc? This should tell us if it is a buoyant 'thing', or just wafting round etc.

Where about was the previous hose delamination, at the tank, or closer to the donk?

From your previous comments (no tank vacuum/hissing from fuel cap but primer bulb sucks flat) we can totally rule out a breather issue.


...This is what I am going to do. I have a guy with a big petrol sucky thing coming around next week. I have made up a spear that can go to the bottom of the tank thats much bigger than the pick up to quickly drain the tank and hopefully pull something out of it. ... Is his 'big sucky thing' :) rated for a continuous duty cycle Shane? Where/how were you planing on using the spear, down the filler opening?

The problem with this is that you are sucking from a different part of the tank.

We know that it is most likely a foreign object blocking the pickup. I would first look at using a continuous pumping process with your mates pump.

Can you get to the pickup easily, and unscrew/withdraw it? From previous comments I assume so. If so unscrew it and leave it sitting in place. Suck out of it through a primer bulb, then filter, then pump, then back into the filler pipe (assuming it is up the other end of the tank).

This will create a continuous process were you are drawing the object to the pickup. When the bulb sucks flat you know it is on the end of the pickup. Hopefully with pump still running you can carefully pull the pickup out and find your problem.

I have made a few assumptions here, and depending on answers to above this may not work.

Typing on an iPhone is giving me the sh!ts, so enough for now.

Cheers

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[Aussie123]

Trying to replicate this issue is nearly impossible as it happens so randomly.
I remember one trip it occurred about 5km offshore from 1770 with full tanks.
It's happened with half a tank of fuel and a quarter of a tank and anywhere in between.
We could burn 1000 liters or more between events as well.
Just when you think the problem has gone away it comes back again and nothing seems to trigger it like certain tank levels, weight in the boat or sea conditions.
I still think the tank has a foreign object moving around between the baffles and occasionally it finds its way to the section with the pickup.
I have been through the system numerous times and magyvered it numerous times to get us home on both motors and it really is annoying.

[Spaniard_King]

Shane,

I have had a similar issue in a cat like yours. the tank isolation valves that come up from the tank on the side of the boat is where I found some black silicon type stuff blocking the fuel system.. this was an 8m noosa cat (ex VMR) with a shit load of hours on it it did my head in for a while too

[ShaneC]

Spaniard King I dont have isolation valves from the tanks because the boat doesnt need them as its not in survey. I have been trying without luck for some reason to attach some photos of the old tank which is sitting out the back which is exactly the same so people can see how its constructed. I will try a bit later from the pc. In a nutshell it is a staino tank with the filler, breather and pick up all welded into the end facing the front of the boat, all pretty close together. The pick up is welded in internally and runs down to the bottom back end of the tank. I can get to all the fittings through an inspection port, however access to the tank itself cannot be achieved without cutting out the floor. It has three baffles evenly positioned through the tank. I know a pic says a thousand words in this case. It will be easy enough to get flow with a pump in the pick up and try to suck it out the filler which is the plan in the first instance, failing that I will try the stainless wire idea (which is a bloody good one), and if it still doesnt work out, I think I will just sit in a warm place and cry myself to sleep in total defeat...

[LittleSkipper]

Spaniard King I dont have isolation valves from the tanks because the boat doesnt need them as its not in survey. I have been trying without luck for some reason to attach some photos of the old tank which is sitting out the back which is exactly the same so people can see how its constructed. I will try a bit later from the pc. In a nutshell it is a staino tank with the filler, breather and pick up all welded into the end facing the front of the boat, all pretty close together. The pick up is welded in internally and runs down to the bottom back end of the tank. I can get to all the fittings through an inspection port, however access to the tank itself cannot be achieved without cutting out the floor. It has three baffles evenly positioned through the tank. I know a pic says a thousand words in this case. It will be easy enough to get flow with a pump in the pick up and try to suck it out the filler which is the plan in the first instance, failing that I will try the stainless wire idea (which is a bloody good one), and if it still doesnt work out, I think I will just sit in a warm place and cry myself to sleep in total defeat...

Why don't you just drain the tank and poke a camera down to see what is in there? If you use a big enough diameter hose to drain or pump out the fuel the foreign object in the tank (if any) may just work its way out whilst draining.. Maybe! Just my thoughts.


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[lutjanus]

Have had the exact same problem . Turned out to be a small plastic lid from a fuel conditioner bottle. My tank was diesel however so bit easier to fix. Why not simply put in another pickup in tank and T into existing line .Whatever in there shouldn't block both

[scottar]

Given that info a couple of things do come to mind. Is the outlet hose well supported through any bends as it comes away from the front of the tank and how sharp are they. Had a situation similar to one that was already mentioned where the hose had enough movement to partially kink itself off under heavy acceleration and cause the engine to die. The second is there any chance there may have been a hole blown in the internal pick up pipe in the welding process that is allowing the engine to effectively suck air as the tank gets down. Have you ever been able to effectively empty the tank to empty using the motor? Just thoughts.

[ShaneC]

Never emptied it to fully empty however it has been down to well under a quarter full. However this issue has happened before within 10 mins of leaving the ramp with full fuel, and there has been plenty of times coming home low on fuel when it hasnt.

[scottar]

Doesn't sound like that then but that's a good thing. Back to trying to get a look in the tank but with the primary entry at the other end to where the pickup draws from, it might be a bit tricky to get where you need to be. I think the plan of a piece of wire is going to be the shot to start with. Are there many bends in the pick up internally in the tank or is it pretty straight? Just wondering if you could shape the end of your wire into a sort of spring shape and create a bit of filter at the entry to the pickup ?

[ShaneC]

Yeah the scope idea is a good one that has been thought of before but the extension would need to be 3-4m long and manipulating it around the baffles would be problematic. Im assuming there would be a bend in the pick up as I would think it would run along the bottom of the tank but I guess that does not have to be the case but it would have to be supported inside the tank. A simple phone call can figure that out.

[samson]

Mate I've had similar issues with different things happening the first was silicon used to seal the sender in tiny balls floating around in the tank clogging the fuel lines and clearing at will i ended up finally getting a dozen tiny little balls work there way through to filter over time and got over the problem a piece at a time.
The next problem was movement in the tank under the sealed deck which would pinch off the lines and starve the engines sometimes one at a time sometimes both so after ripping up floor and putting in chocks solved problem.
The problems I'm having at present seem very similar but I seem to rectify them on the water,I get fuel starvation with one or both motors and but fuel filters are still full,I've tried changing fuel pumps,in line filters ,changing injectors, cleaning injectors and still get starvation usually I end up disconnecting fuel line at filter and pumping flow of fuel through it and reconnecting and for some reason it starts running fine but the jury is still out on this problem.
All these problems become intensified if you snuff out on a bar which has happened a few times,I also had a scale issue from the deck when crew filled up quite often stepping over filler with scales on feet transferring to tank fixed that one also.
Out of curiosity are your motors yammy four strokes because since I've had these i seem to get a few starvation issues.
Good luck champ it a prick of a problem been there and still there. Cheers Randall

[ShaneC]

Yeah mate Yammy 150 four strokes. I never had the problem prior to the new tank however. Everytime I get home after having a drama I get the compressor out and blow air through the pick up which generally solves it for a while. Lately I have just been keeping 100 litres in jerrys on deck because I can run it out of them on the long runs when it happens but that that brings with it obvious pains in the arse when you only need them occasionally, but also saves a long run home on one motor. I guess taking the compressor on the boat could be an option. I have been pretty lucky with the timing of the events, got caught out once in a bit of swell coming in the Breaksea but its only one motor that plays up so managed to limp across the bar. PM me mate if you suspect you have something floating around your tank now, a mate has put me on to a very powerful pump but it cant do petrol, if i have no joy I will empty my tank and fill it with water and give it a go.

[Dignity]

Can you remove the tank and flush it, from memory it was over 300 liters so would need to be used a fair bit to get it down in volume or syphon it to a few 60l drums. A problem I have noticed of late is some sort of rubber pieces in the plastic jerries of late, always had the tin ones but about 6 months ago bought some plastic ones as the others were showing signs of rust. I use jerries as my boat likes a slow fill, what I have noticed lately is a number of rubber like particles left in the bottom recently. This has me concerned as I fill up generally at the same servo and hadn't noticed this before. I cleaned these out and then refilled them and after nearly emptying the jerries found more rubber like compound in the bottom.

So if this is happening to you it could be your problem, just clutching at straws here but if it happens again with me I will be approaching the supplier as third time is no longer a coincidence. I do hope you find a solution as intermittent problems are the most hardest to resolve as well as the most frustrating.

[ShaneC]

Cant remove it without substantial cost and time both of which are certainly not ideal. I sometimes fill up with jerrys when at sea or when i fill up at home to save the hassle of towing the boat to the servo but have never seen anything come out of the jerrys (not that I sit there and watch the siphon hose) but I always empty the last bit of each jerry on the weeds and so far have not seen anything substantial come out of them.

[Fed]

Have you proved 100% that the blockage is at the pickup inside the tank or could it be blocking up outside the tank and you're blowing it back in to repeat the cycle?

[Fed]

What's the layout of the tank baffles, cutouts in the baffle corners & multiple holes in them?

[ShaneC]

Main reason I think it is within the tank is due to sucking the primer bulb flat as a pancake. That to me eliminates air getting entrailed into the system and says to me its in the tank. Undoing the primer bulb at the tank side of the filter allows you blow air out of the pick up which fixes it for a while. Once it starts to starve, if you turn the motor off, leave it for a bit and start it again it goes fine for a time then starves again. My way of thinking is that whatever it is, its bigger than the pickup so by turning the motor off, ceases the vacuum effect and it falls away for a time. I have also found that running a bit slower (at say 3500 rpm) lessens the incidence of it, maybe due to less vacuum, I dont know. Having said that, in an attempt to make it happen for a video, I ran it at 4500 rpm + for three days in great weather off Agnes a while ago. Of course nothing happened.....

The baffle set up you suggest sounds right based on the stitching I can see on the externals of the old tank, not sure about holes in the baffles, but I would think there would be.

Shane

[ShaneC]

If I can manage to get hold of a portable unleaded pump I can manipulate the air dock the boat is on to be nose down and leaning to the right (the side of the filler that will be used by the spear) and in theory the object the dragged down on that side through the baffle corner cut outs and straight to the spear. In theory.... thanks for asking that question it opens another option to try....

[Fed]

I'm not convinced it's not something as simple as the breather yet.

For what it's worth my breather salting up was on the breather mesh caused by the dreaded sharkcat mist and the breathers were mounted up on the sides of the cuddycab. The mist simply sucked into the mesh and sort of built up... sometimes.
As you probably know that mist is highly unpredictable.

Have you ever tried it with the filler cap off or are the breathers just an open hole with no mesh at all???
Convince me :)

If you eventually go with the spear I'd hook a garden hose to the tank pickup tube and blast water in there to help flush the crap from the back to the front.

Have to add I'd have a slight concern about air dock rollover by tilting, you'd never live it down. Jeez that would be embarrassing.

[ShaneC]

Im pretty confident its not the breather, we have run it with the cap off and it hasnt fixed it. Im not too concerned about tossing the airdock, that stuff happens to other people, but I will now lash it to my pontoon now that i have opened my big mouth

[McKnight]

One thing you can do to create a cheap vacuum that should be easy enough to manipulate to the far end of the tank. I can't guarantee how safe it is with fuel, If you filled the tank with water its perfectly safe. this is all assuming you have an air compressor. below is a cheap ejector type vacuum.

Get a length clear plastic hose (20mm) long enough reach the bottom of the tank, and to point somewhere you want the water or fuel to end up. A cheap compressed air blower with the long nozzle. Poke the nozzle into the hose in the direction you want it to flow, fire up the compressor and you have a cheap vacuum that can be poked just about anywhere. If the object is to large to be pulled through the hose, continue blowing air through the hose and remove it from the tank. I have used this method to successfully remove washers and crap from an 80L tank. Although I could shake the tank around.

[cormorant]

Next time fuel bulb id sucked flat prove the issue is the tank by cutting hole in fuel line on tank side and see if the bulb recovers shape? If it doesn't it is at the bulb. I know you have replaced the bulb but.... Does it only happen at higher rev range? Is your fuel bulb mounted vertically or horizontally?

Unfinished sharp ends on stainless feed pipe exiting the tank can delaminate the fuel hose where it attaches to the tank. That took us a while to work out as at random times teh delaminated hose would act as a flap valve . We did it a couple of times with new hose and the nitrile lined stuff did it. Cleaned up hose tube edge and problem gone.
just a few more dumb thoughts.

I'd be buying a ebay $30 10m 12mm endoscope and draining tank and going for a fish with it attached to one of those cheap $10 sewer clearing springs . Just need to test the camera in some petrol / fumes for 20 minutes somewhere safe first as it may dissolve or lens may cloud straight over or insulation degrade. At your own risk of course.

You can rent pro borescopes as this company has supplied thermal cameras to a business I know in the past, (07) 3717 9100 http://www.techrentals.com.au

[Fed]

The trouble is comorant that the crap is in the back of the tank and the pickup is at the back of the tank but exits at the front of the tank. The only feasible access hole is the filler hole also at the front of the tank.
Problem, there's baffles in the tank and at this stage an unknown quantity and configuration. Hoping the corners of the baffles are cut out to allow the crap to flow from the back to the front.


Im pretty confident its not the breather, we have run it with the cap off and it hasnt fixed it.
I'm convinced Shane :)
Now, as said above, find a way to prove the crap isn't collecting between the outlet exit from the tank & the primer bulb.

It's doubtful to be anywhere else other than in the tank but it would be nice to prove it before getting started eh?

Pickup-->hose-->metal line-->hose-->primer-->filter-->motor?

Can the tank maker provide any baffle info?

Final thought, it would be nice to catch the crap in a sieve just to know you found something.

[shaungonemad]

I had a lot of trouble with my system because the internal size of the fittings were to narrow it would be fine for a while then it would lose pressure and would have trouble pumping up after we made them bigger it was fine.But it sounds like something in the tank.

[Darren J]

I just happened to run across a post on The Hull Truth with guys reporting the same problems, irregular sealing of the supply form tyne tank.
Seems that they all had knowingly lost the small coated paper seals from the top of fuel additive bottles into the tank (by mistake or just dumb luck). I was surprised how many guys posted in having encountered this problem over the years...
Some encountered the supply dramas you are having intermittently in the way you are, others never did have the problem after many years of use. Some fished them out, with GREAT difficulty.
Effect ion any given tank appears to depends on the configuration of the pickup, whether they use of an extended mesh gauze strainer etc or similar.

It does seem to support the theory of something floating about in the tank as the likely cause.

Can you get to the section of tank directly over the top of the pick up inlet for direct visual of that chamber as well as the pick up itself. maybe put in an inspection opening (with screw in stainless cap to seal up) to close it off?

[ShaneC]

Im at Plan T now. With everything stated in mind I came up with this today. I wanted to get the fuel out of the tank so I got hold of an external fuel pump that they use to replace buggered pumps on race cars etc. Got a 10mm piece of pipe down the filler and pumped out the 170 litres that was in the tank by getting the boat in a bow down, starboard leaning attitude (you are right Fed, I lashed everything up so it could not topple but it was horrible to be standing on and got attention from the poor neighbours). So we are now bone dry empty, there is maybe 2mm on the dipstick in her front down attitude and nothing as soon as you start to lift the bow, so at max maybe a couple of litres left. I am trying to source a trash pump or fire pump now with an inlet less than 50mm (the filler diameter) and I am going to fill with water through the tank pick up to get things moving and draw it out through the filler with a pump capable of getting it out quick. With the boat back in her precarious angle, the object has to move through the corner cut outs of the baffles towards the front to a big sucky thing which I will pump into my 800 litre ice box lined with thick plastic. If the bin fills I will drain it and go again. When (hopefully) I see the culprit in the box, I will do a little dance, crack a rum can and ceremoniously dispose the object to the shithouse. Then I can wrap up the liner, dispose of it responsibly if there is sludge in it, then get on with life. Am I missing anything? Thanks to Lance for chipping in on my plan. If anyone has or knows someone with a pump that can do the job, there is money/ beer/my sister in it for you.....

[Fed]

Grab a swimming pool pump.

[cormorant]

Hi Fed . Tank builder will have done greater than 40m cut outs in baffles so it should be able to work. You would be amazed with a bit of time where you can push a 8mm camera on a bent bit of flexible push cable ( twisting it to walk it into holes) . We have saved hundreds of thousands in non destructive membrane repairs in buildings by being able to discover and diagnose the exact failure points and also confirm the structure rather than have a bunch of knobs tear it all apart at our expense rather than the original warranty. Even the cheap nasty ebay ones are waterproof and give great colour pictures with led lighting. I am all for trying anything non destructive these days and if the tank is empty and blow air through it to get rid of the last bits or pour as a flush a bit of kero or diesel that doesn't fume / explosive vapour the same way and it become pretty low risk. The cheap nasty ones just plug into a USB port on your laptop like a webcam

Have pulled half a dozen tanks out of old boats and always amazes me the stuff in them or reason they fail but a new tank has me a bit mystified unless it is rag or such.

[marto78]

Hey mate I've got a spare pump with filter for a blow up pool in the shed if you want it.

[ShaneC]

Of course I want it mate. I will text ya and see if you are up

[ShaneC]

My mate who is heaps smarterer than me said the same thing Fed. I dont want to go drilling into the tank so yours and his idea with the pool pump is the way forward

[gofishin]

Any feasible plan is better to try before resorting to 'destructive' means :).

Is the filler cap through the coaming/side deck? Can't recall if this has been mentioned. If so, it will be what, ~0.9-1m above the top of the tank?? (and whatever liquid you have filled the tank with).

Many pool pumps will not self prime at this height, so it might pay to experiment a little and even have a way to help it prime.

One other consideration Shane...it has been mentioned that the problem has happened just after leaving port with a full tank, as well as anywhere in between down to a 1/4 tank.

If it is something in the tank, this means it is 'wafting' around and not 'floating' around, i.e. the object's relative density is greater than that of ULP which is ~0.76 depending on temp. However, how much greater we don't know.

If it is greater than ULP but less than water (1.0) , the object will then float when you fill the tank with water. This might make it harder to find/extract.

If you empty it a few times without finding the culprit, I would still try to flush it (one end to the other) as well when there is a few inches of water still in the tank, ie, force water down the pickup if you are sucking from the filler.

You might not be able to get much flow down the pickup, but in my mind it would still help.

Good luck!

Cheers
Brendon


Sent from my iPhone using Tapatalk

[Fed]

I reckon it's a sinker rather than a wafter or a floater and when it gets near the pickup the flow is sucking it in. Of course I agree water could change that.
A good mate of mine had this problem & it turned out to be of all things aluminium swarf in the tank, it was self inflicted but to give him credit he did build 5 plate boats ranging 6-8M over about 3 years.
You may be looking for a lot of smaller things rather than a bigger lump.
If you start with a full tank & the pool pump sitting less than ~8" above the water level I'm sure it will prime, my pool self primes at that height.
Love to see a picture of the pipes through the inspection hole (hint).

[gofishin]

By wafter I meant all over the water column and not floating Fed. But yes, it could always be a bottom dweller, however if so I would have thought the problem would be more prevalent.

I suppose it could also be a rock !!! :). Time will hopefully tell.


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[ShaneC]

Fed, when it stops pouring rain I will try. I am having trouble uploading photos off my phone and the old girl is overseas and took the laptop with her. If you like you PM me your mobile and I can text you some phots I have taken of the old tank to satisfy your curiosity.

Picking up an old pool filter this morning with 50mm pick up and a filter cartridge. This thing is coming out today....

[Fed]

It sure is going to be interesting gofishin.


This thing is coming out today....
That's the spirit!!!

Another thought, you did ask for opinions...
I'd be turning the tap to the fuel pickup (flush) on & off every few minutes to give the crap a chance to drift along with the current flow, you wouldn't want the water blasting from the pickup to hold the crap away from the low side. Turn it off for a few minutes every now & then.

No good sending me a pic with a text my dumb phone doesn't seem to be able to send or receive MMSs, I know it should do it but I'll have to ask a young person how to make it work.

[Darren Mc]

It sure is going to be interesting gofishin.


That's the spirit!!!

Another thought, you did ask for opinions...
I'd be turning the tap to the fuel pickup (flush) on & off every few minutes to give the crap a chance to drift along with the current flow, you wouldn't want the water blasting from the pickup to hold the crap away from the low side. Turn it off for a few minutes every now & then.

No good sending me a pic with a text my dumb phone doesn't seem to be able to send or receive MMSs, I know it should do it but I'll have to ask a young person how to make it work.

Hi Fed,
Might be a silly question that you already know about but do you have your your mobile internet switched on when you try to send or receive mms. If that doesn't fix the problem I have no idea what else it could be.

[Fed]

Thanks Darren but I did try it with every possible combination of voice and data and also home internet via wifi. Also got the camera set on the lowest resolution to keep the file size down. All my neighbours have younger kids so I'll be ok I guess. It's my first smart phone (cheapy) so I haven't learned all about it's working gizzards yet.

Back to Shane, sorry for the mini hijack.

[Darren Mc]

Ok no worries.