Hard to start after a few days?

[hanleyclifford]

Please read John Cookson's post (#4 in this thread), he is spot on. Fuel pump operation during cranking should have nothing to do with starting. If it does your carb bowl is emptying during layoff and that needs to be dealt with directly rather than with another band-aid workaround.

The OPSS is there for safety. The electric fuel pump is not allowed to operate when the engine is not running. I'd like to know what the USCG thinks about defeating the OPSS during cranking by using a solenoid terminal originally intended for an entirely different purpose (ballast resistor bypass).

Excellent question.

[sail_flathead_lake]

I agree wholeheartedly with this statement:

"Don't think it has anything to do with the OPSS. The carb bowel should be full of fuel from the last run and give ~45 seconds of run time even if the OPSS is not functioning at all"

When we launched the boat I had started the engine the night before, then forgot to open the fuel petcock after the boat was launched. It started right up at the dock, but of course died a minute later. This evidence suggests that if there's gas in the bowl, it starts, regardless of the OPSS. I think that the hard starting must be due to gas leaving the bowl somehow. If it were a carb issue it would be hard to start after the engine cools down completely, but this engine is hard to start only after sitting for more than a couple of days.

If we buy the idea that lack of fuel in the bowl is the culprit, then we must assume that fuel is leaving either by leak or by evaporation. For fuel to leak out of the bowl, wouldn't the leak have to be in the bowl itself? Can fuel leak back from the bowl through the fuel line? I would think that this would be impossible, unless it's somehow being siphoned out.
If it's evaporation, why doesn't everyone have this issue?

Could I check the theory by removing the plug for the bowl and seeing how much fuel drains out?

[JOHN COOKSON]

but this engine is hard to start only after sitting for more than a couple of days.

If you have points file 'em and regap 'em. Any moisture inside the distributor cap?

TRUE GRIT

[Dave Neptune]

The fuel in the bowl can not syphon back!!! The fuel in the lines can though.

Every carb and application of a carburetor has evaporation as the carb is vented and gasoline evaporates even at very low temps!!!!!!! As to whether or not it is noticed is up to the observer.

Dave Neptune

[marginal]

My money is on choke adjustment.

I had the same symptoms - easy start if run recently (a day or two), otherwise much harder.

The clamp on my choke cable was slipping, and since I've fixed it, the engine starts on the 3rd or 4th revolution every time.

No idea why the 'easy start' window was so long. Maybe there is fuel vapor in the manifold that takes a while to dissipate.

Simon

[edwardc]

My money is still on sticky valves. It explains all the symptoms and doesn't leave any unanswered questions.

Occam's razor. The simplest explaination is usually the right one.

[sail_flathead_lake]

And the fix for sticky valves is to toss some Marvel Mystery Oil in with the gas? Or is there a better treatment?

I will check the choke too - I assume that if I remove the flame arrestor I should see the choke close all the way when the cable is pulled, correct?

Thanks!

[edwardc]

Adding some to the gas will get to the top part of the valve stems, while adding some to the oil will get it to the bottoms.