Start quick, idles rough, then dies

[Chris G]

Put boat in water, started quick, idled fine. Left dock, accelerated and ran good for 15 min before quitting, would not restart. Afer several attempts it would idle but die when gas was applied. Now at dock, starts quick, idles rough and dies when given gas. So far I only hooked up an auxillary tank and that changed nothing. What is my next step?

[ndutton]

As a test, try running with partial choke applied and report back.

[Mo]

Easy things first.

Could be a combination of things.

If you had winterized your combustion chamber with oil the plugs may be fouled. Remove and clean as necessary. Once the plugs are out for cleaning do a quick compression check also....just to rule out sticking valves. Check for loose wires, if points and condenser have a look at those. Check for loose wires on coil etc. Just takes a few minutes to have a quick look.

You have attempted to address a fuel issue and the issue may be in the carb itself. You could try removing the main jet and ensuring it's clear. If that doesn't do anything for it you might have to remove the carb and clean it up. MMI has a video on how to do that if you are unsure....however, as long as you are careful in taking it apart it's not hard to do at all. You have rigged up an auxil tank so that pretty much rules out water in the gas and bad gas.

So have a good look at everything, take your time. Try to run the engine after each intervention....ie) clean plugs...see if it runs. If you just go and do multiple repairs you may never know what the true problem was.

[Chris G]

Partial choke had no effect, nothing appears loose, so I guess it's on to the carb. No reason to check fuel pump?

[ndutton]

There's a threaded plug on the bottom of the carb. You might try removing it to see if fuel pours out (have a catchment under the carb for this). No fuel suggests a fuel delivery problem somewhere, perhaps the pump.

Mechanical or electric fuel pump?

[Mo]

Personally I'd go to carb next. If you have a small air compressor those do a really nice job cleaning the jets once removed. I wouldn`t tackle the fuel pump just yet...might very well be a carb blockage. Pump can be looked at if a carb cleaning doesn`t do the trick.

Check and clean plugs as well. Considerable carbon deposit can be on them if they burned off oil from winter storage. A bunch of small problems can present as a major.

[Mo]

Neil, you type fast....I`m still typing and you are posting. Same general area of things. Just so you know I`m not trying to contradict your reasoning.

[ndutton]

No problem Mo. The more ideas the better.

[13jeff13]

There's a threaded plug on the bottom of the carb. You might try removing it to see if fuel pours out (have a catchment under the carb for this). No fuel suggests a fuel delivery problem somewhere, perhaps the pump.

Mechanical or electric fuel pump?

Clogged Fuel Filter??

My .02

Jeff

[jpian0923]

If the engine can't "inhale" or "exhale" it won't run well. Check/remove flame arrestor, see if it runs better. If that doesn't work, check/remove exhaust from exhaust flange.

[ArtJ]

Flushing the main passage jet is the normal first step recommended by
Don Moyer when have symptons like needing choke after winter storage.

[Chris G]

Thanks for the good ideas, I can't get to the boat till Friday. I'll let you know how it goes

[Chris G]

Ok, at the boat today, sprayed some carb cleaner in and boat ran great. Ran it for 20 min, put it in gear, forward and reverse, accelerated, no problems. Then all of a sudden it starts to run rough and when given gas she stalls. Several attempts yielded same results. So I am going to clean carb, replace gas filter and lines, then pump tank and replace fuel. Does this sound like a good plan?

[smosher]

Sounds like the float valve is stuck, a common occurance.

Yes cleaning the carb should be the 1st thing done.

Steve

[ArtJ]

I would suggest flushing the main passage jet first and pump out a cup of
gas before taking carb apart . that often solves the problem.