Engine Starting Issue

[Gabe]

I have been having an issue with getting my A4 started at the end of a sail. It starts fine at the dock, but after sailing for several hours I have to turn it over several times to get it to start. This past weekend I could not get it to start at all. I removed the plugs and they were black and wet. I cleaned them off, re-installed and cranked again. No start. Took the plugs out again and they were wet again. So I shut off my fuel supply valve and cranked a few times to empty the excess fuel out of the cylinders, cleaned the plugs again, reopened my fuel supply valve and it started right up, although it would die again at idle. So it seems to me that the engine is running very rich and flooding out. I rebuilt the carb last fall and installed a fuel filter. I am going to replace the fuel pump because it is very old and doesn't have an oil pressure safety switch. Could a failing fuel pump pump too much gas? Is there anything else I should check out while I'm replacing the pump? Thanks.

[JOHN COOKSON]

1st thing to do: Check the choke.
Is the choke all the way open when you think it is and all the way closed when you think it is?

TRUE GRIT

[edwardc]

It's possible that your float valve is not seating properly. Once you stop, the pressure in the fuel lines slowly bleeds past the leaky float valve, flooding the carb, which then doesn't want to start.

Once it does start, the leakage is causing it to run too rich.

It's a theory that seems to fit the facts. Needs experimentation to verify or disprove. I would open the carb and check & clean (or replace) the float valve needle and its seat before replacing the fuel pump. Also, check that the float bodies are both empty and not partially filled with gas by shaking them next to your ear and listening for sloshing. There should be none.

[Carl-T705]

What type of fuel pump are you discussing?? Fuel pumps don't have a oil pressure safety switch.

[Mo]

Check the exhaust. If you were sailing and can't start easily water in the combustion chamber could be an issue.

[hanleyclifford]

When you leave the boat you no doubt shut off your fuel supply at the tank whereupon what remains in the line slowly (and in your absence) moves down thru the leaking needle and seat, into the arrestor and finally to whatever lies below. By the time you return to use the boat the fuel has cleared and dried up and you have no problem starting the engine. While sailing, especially if you leave the fuel line open, the leaking proceeds but does not clear the line nor dry up before you want to restart. The solution is a small shutoff valve right at the carb (about $10). The needle and seat on our carbs is not to be considered reliable for containing fuel except very temporarily. Even a new one can get a little piece of crud lodged in it, and the purpose is totally defeated.

[roadnsky]

Opss

What type of fuel pump are you discussing?? Fuel pumps don't have a oil pressure safety switch.

Huh?
Mine does. It's a Coastie requirement.

[sastanley]

Jerry, I think Carl's point was that an OPSS could be added to any fuel delivery system, and that a new pump still won't have one, and it would have to be added regardless.

I think.

[roadnsky]

Jerry, I think Carl's point was that an OPSS could be added to any fuel delivery system, and that a new pump still won't have one, and it would have to be added regardless.

I think.

Ok, I can see that.
Whew!

Thanks pal!

...and sorry Carl

[Gabe]

yeah, I understand I can add the OPSS to the current pump, I was just meant that while I'm down there doing that I'm going to switch out the pump because I have no idea how old it is (it looks OLD, no identifying marks on it anymore) and keep the old one as a spare.

Thanks for the suggestions so far. I will check out the exhaust and the float valve and get a small fuel shut-off valve at the carb.

[CalebD]

Fuel tank clean?

Gabe,
Is your fuel tank clean and free of the dreaded E10 crud from ethanol laced fuel?
We had a lot of crud in our tank (before I pumped it out) that played havoc with the float valve in the carb and caused other serious performance issues.

A tank that has been sitting still will have the crud at the very bottom. A tank that has been agitated by a vigorous sail will have crud mixed into higher levels of the tank.

[Gabe]

Gabe,
Is your fuel tank clean and free of the dreaded E10 crud from ethanol laced fuel?
We had a lot of crud in our tank (before I pumped it out) that played havoc with the float valve in the carb and caused other serious performance issues.

A tank that has been sitting still will have the crud at the very bottom. A tank that has been agitated by a vigorous sail will have crud mixed into higher levels of the tank.

That could be an issue. Would all that crud be able to make it past the fuel filter though? Did you have in-line filters in place when you had your problems?

[CalebD]

Filters

Gabe,
Yes, water separator & in-line filter as well.
It does not take much crud to mess with the float valve needle.
Our fuel tank was ignored for far too long though and was quite dirty.

I think the classic symptom of having dirty fuel is if/when you do get the engine running it does not idle at a consistent speed but rather "hunts" for a speed it can maintain. This happens without you touching the throttle as impurities get sucked into the carb. If your engine does not exhibit this "hunting rpms" symptom I'd look into all the suggestions made by the rest of the crew here.

Seems like the consensus is that the carb is the likely culprit if your fuel tank is clean.
One trick I learned here was when engine wouldn't start or run consistently is to remove the main passage plug screw from the carb. I'd put a clean cup under the carb to catch the few ounces of fuel that would drain out of the carb. Let the cup of fuel sit and observe if you see any impurities (water, crud etc) floating at the bottom. Usually this temporarily fixed the problem. The more permanent fix for me was draining the fuel tank.

[Loki9]

Gabe,
Is your fuel tank clean and free of the dreaded E10 crud from ethanol laced fuel?
We had a lot of crud in our tank (before I pumped it out) that played havoc with the float valve in the carb and caused other serious performance issues.

A tank that has been sitting still will have the crud at the very bottom. A tank that has been agitated by a vigorous sail will have crud mixed into higher levels of the tank.

Do you get a nickel every time you post that photo?

[romantic comedy]

I love Caleb's gooy gas photo.

Makes me think 2 things.

1, I am so glad that I dont have that problem.

2, It makes me want to make salad dressing.