Fuel problem. Opinions??

[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