Help with contaminated fuel?

[fender22]

HI, I recently renistated the underfloor fuel tank in my boat. Its about 100l stainless. It was in the boat when I got it and wasn't connected and full of water! ANyway, I removed it and completely drained water, then filled it with 4 liters of metho, slooshed it around and let it sit for several hours, then slooshed again and let it sit. I kept revolving the tank around so it would get into every crevice. Then finally I drained all the metho out and let it sit over night. Hooked it all up and everything seemed fine. I took it out today and was a bit hit and miss starting. Thought it was flooding, then starving. Anyway, it finally started and it was ok and it was temperemental all day when it normally starts pretty easy when warm espescially. I have a proper fuel filter (looks like an oil filter) on and I have no doubts the thing is "breathing" properly, as a matter of fact it was sweet as a nut once going and smooth as ever once it was started. Has anyone had any experience with this? Does this sound symptomatic of conatminated fuel? What can I do? I used most of the fuel int he tank today so due to give her a fresh fill of fuel.

[tunaticer]

If you are sure you have no water in the fuel again give it a fresh dose of fuel is the first thing and see if that settles it down.
I would be fitting a water trap with a clear bowl in the fuel system somewhere so you can monitor what goes through with the occasional glance.

Jack.

[fender22]

As far as I know there was no water left in it, I was pretty rigorous about flushing it all out with the metho. U never know though, has baffles etc inside the tank so could be possible there were a few drops left behind. There was nothing sludgey or solid came out of the tank when I flushed it and I was really careful hooking it up etc.

[Roughasguts]

Have you drained your carby's ?

If there was water then it's still in your carbs.

Theres a little screw at the bottom of each carb it has a spring on it to stop it rattling loose. Un do that a few turns until all the fuel comes out, then prime the fuel primer a few times to flush any crud through. Tighten screw and your in buisness. If you can catch the fuel to see if water was in it.

[fender22]

Would it be hard to strip down the carbs and give them a clean? I'm not a super genius with motors but have stripped down simple motorbike carbys, cleaned the needle / seat, made sure the float was ok. I've felt the carbys needed a good clean since I bought the boat. It's an 87 Mariner (Merc) 135hp V6

[Roughasguts]

Trouble is fender the gasketts will need replacing as soon as you remove the carbys, also the float bowl gasketts. I make my own and now have a spare for a template for next time. (plus I used grease instead of Goo) So if you start now you won't be using your boat this Easter.

Mate I pulled my carbs down a few weeks ago and really if it wasn't for the corroded needle and seats in two of them it wasn't really required.

I would just do the flush thing with the carbs, then maybe conect the fuel primer hose before it branches of to each carb, so seperately fill each float bowl with fuel to see if the needle and seat are doing there jobs. Then drain the float bowl to make sure it has plenty of fuel.

But I reckon the flush will do it for now.

Fender outboard carby's like the Mikuni, are very simpleyou won't have any trouble with pulling them down. It's just fixing things that don't need fixing I'm oposed to. Fill her with PULP next time out that fuel has good cleaners in it.
But then stop using the PULP no need every trip.

[fender22]

Thanks mate, a bit lost though re how you can tell if the needle and seat are working?

Do the symptoms I'm having seem consistent with water in the fuel? Of course it could be anything but seems like the obvious cause. And the water stays in the bowl eh? How about a bit of metho in the fuel tank or is that an old wives tale?

[Roughasguts]

I have never tried Metho, bu t I beleive it has some merit.

If you attach a fuel line to a single carb and prime or pump fuel up to it, once full the float in the carb will close the needle in to the seat, and you can't pump any more fuel in it until you have eithe drained the carb or the engine uses it.
Mind you it does evaporate too.

To me it seems like water in the bottom of your carbs making it hard to start once running there will be enough turbulence in the float bowl with the extra fuel going in to keep the engine running even with water in it.

But we won't know for sure until you try it, so if it works initially and sometime later it plays up again then you will need to drain the carbs again until all the water and gunge is removed.

[Mark-P]

Just a stab in the dark but, when was the last time you changed your plugs ? If waters gone through the motor the plugs would have rust on them !
Just my opinion .....

Mark

[hookinin]

As roughasguts said i would try draining and flushing bowls but also if you havn't had your fuel filter off i would take off the cartridge and empty contents into a container to see if anything in it. If it is contaminated renew it. Also should make sure inline primer is not allowing fuel to drain back. Gaven

[Xahn1960]

My 88 Merc 225 V6 did the exact same to me when I first got it a few months ago, new plugs and filters fixed it, hasn't missed a beat since.

Bill.