Keeping the engine running

Jun 16, 2020
71
Hinckley Sou’wester 30 Falmouth ME
I have an inboard gas engine that I has been giving me troubles since commissioning this spring. At first, it wouldn’t start at all and I learned that I needed new batteries. Done. Then it would run for a while allowing me to get underway, but when I returned from a day sail it would not restart. The boatyard mechanic and I suspected air was getting into the fuel line so that it was losing suction (perhaps when the engine heated up?). So we replaced the fuel filter and installed a hand priming pump. Yesterday (after Isaias) I started the engine up and it ran for about two minutes then died. I primed it and again, it ran for about two minutes. After the third time (riding the edge of “insanity”) of priming, it ran for 15 minutes after which I shut it down.

Any thoughts on what might be happening?
 
Jun 16, 2020
71
Hinckley Sou’wester 30 Falmouth ME
Good point. The fuel pump had been replaced by the previous owner within the last two years, but it could be failing already.
 
Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
“Giving you trouble since commissioning” begs the question what was done with fuel system then. New filter, checked fuel lines, etc...?
 
Jun 16, 2020
71
Hinckley Sou’wester 30 Falmouth ME
The same boat yard did replace the fuel line from the tank when they commissioned her.

WRT the carburetor - what do you think might be going on?
 

dmax

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Jul 29, 2018
971
O'Day 35 Buzzards Bay
A vacuum leak is excess air getting into carb/intake. All combuston air should come through the throat of the carburetor - the path from the throat to the intake valves in the cylinders should be air-tight. Look closely at any rubber hoses that attach to the carburetor (not fuel lines) for leaks. Make sure the carb and everything else in the path is tightly bolted down and any gaskets are in good shape. Get a vacuum gauge (they're cheap) and test it, this page shows how to diagnose problems:
 
Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
The same boat yard did replace the fuel line from the tank when they commissioned her.
This is one of those guessing games we sometimes play when it’s impossible for us to examine what they did This is too coincidental that you have a fuel problem after they worked on the fuel system. My guess is this is self-inflicted by your yard guy.
 
Jan 1, 2006
7,040
Slickcraft 26 Sailfish
Bad fuel? There are services that will come and empty your tank and either cart the fuel away or polish it and return to tank. You can test the fuel by using a portable outboard tank with new fuel. Hook the hose up to carb intake and see how it runs. Be mindful of the gas vapors from the portable tank! If the existing fuel is contaminated with Alcohol/water you'll prolly need the carb rebuild anyway.
 
Jun 16, 2020
71
Hinckley Sou’wester 30 Falmouth ME
More good suggestions. The vacuum test article is terrific. I didn’t realize how much diagnostics you could do from a vacuum test!

The fuel is interesting. The guy I got my boat from was a purist and had pure gasoline in the tank. When the yard filled it up for the season, though, they put in the gas/ethanol mix. I have no reason to believe it isn’t fresh fuel.
 

Tedd

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Jul 25, 2013
745
TES 246 Versus near Vancouver, BC
Sounds a lot like pulling a vacuum in the fuel tank. Make sure the tank vent is clear (and open).
 
Jun 16, 2020
71
Hinckley Sou’wester 30 Falmouth ME
OK Ralph, I am feeling pretty dumb right now. The hand primer is a soft (I don’t know if it is literally rubber) hand priming up put in by the yard. The guy who did it has been around sailboats for many years, so I had begun to trust him. The priming line has a shut off valve that isolates it from the engine that I was shutting after I primed the engine and before starting. What should I be concerned with?
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
What should I be concerned with?
My concern is that the bulb doesn't have the resistance to mechanical damage that you see in a hard rubber fuel line. There is the possibility of the bulb being subject to either abrasion or cutting from accidental contact with anything sharp, a condition which could easily be encountered in rough seas. I don't know what the ABYC regulations state as I do not have a copy.

I am far more concerned about the fact you are moving highly volatile gasoline around your engine compartment as opposed to diesel fuel. I don't think you'll ever hear of anyone complaining about their fuel system being too safe.

You may want to look at one of these as a safer method of moving gasoline:

Fuel Pump specs.JPG

This is not necessarily the answer to your starting problem it's just safer that a rubber priming bulb below deck.
 
Dec 2, 2003
751
Hunter 260 winnipeg, Manitoba
Do you have two fuel lines running from tank to some single point before engine? Normally a rubber priming bulb is on a single main fuel line and fuel then is pushed/pulled through bulb by fuel pump. It could be the isolation valve you mention is the main fuel shut off which would result in a few minutes run time.
In any case I would agree with the others that the standard rubber squeeze bulb has no place below deck on a gas fuelled engine. They have too great a tendency to leak in various ways.