One engine getting bad gas, both pulling from the same tank...also a fuel leak?!?

Luke415

Seaman Apprentice
Joined
Apr 4, 2016
Messages
42
Noticed that one of the engines in my twin outboard setup is getting murky gas after the engine just cut out suddenly. I emptied the fuel water separator and replaced with fresh gas. It ran fine for a few minutes and then stopped running again because of bad gas I'm assuming...? The gas looked like a rusty color. Both fuel/water separators are new, and there is only one gas tank for both engines. The boat was just in the shop and they tested the gas and said it was fine. Why would one engine be getting good gas and the other getting bad gas? I do not understand how this could happen. I also have a fuel leak which I am wondering if it could be somehow related.

This is a new boat to me which I have only taken out a few times. Here is all the info: The first time I took it out I did not notice a fuel leak. One of the engines had a powerhead go bad so I had to have a new (used) engine switched out. The engines are/were '98 Merc 150XL 2 stroke w/ carburetors. The outboard that they replaced for the bad motor is a year older but and EFI model. They also replaced the throttle/shift cables and put a new sending unit on the gas tank for the fuel gauge. The tank is plastic and the boat is a '98 Starcraft Expedition fiberglass. The fuel tank is built into the boat and is impossible get access to most of it without cutting up the floor. There are access ports to the hoses and fittings on the tank.

After they switched out the engine and did the other work I took it out and noticed a very strong fuel smell. I was hoping that maybe the mechanics accidentally spilled some fuel while switching out the engine and perhaps it wasn't a leak. I pulled it out of the water, raised the trailer tongue about 4 feet to get a good angle and flushed a ton of water through bilge. Next day the bilge had drained and did not smell as gassy. Took it for another test run and sure enough, more fuel in the bilge coming from somewhere. Can't see any leaks so I guess my next step is to pressure test the tank and see if I can find any leaks. I guess it's possible the mechanics could have started a leak while working in the boat, maybe bumped an old hose and started a crack or loosened a fitting? I don't know how old the hoses are but I am guessing many years old.

Could the leak and the bad gas to one engine be related? It sounds like a separate issue but maybe someone else has had a similar problem...?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,418
Do both engines pull from the same fuel pickup. or does each one have it's own? Maybe the murky fuel is on the bottom of the tank, and one fuel pickup is longer than the other?
 

Luke415

Seaman Apprentice
Joined
Apr 4, 2016
Messages
42
Do both engines pull from the same fuel pickup. or does each one have it's own? Maybe the murky fuel is on the bottom of the tank, and one fuel pickup is longer than the other?
I'm not sure. I'm planning on looking into that tomorrow, have to pull out the remote oil tanks and the batteries to get access to the bilge area and the fuel lines coming from the tank.
 

Luke415

Seaman Apprentice
Joined
Apr 4, 2016
Messages
42
Do both engines pull from the same fuel pickup. or does each one have it's own? Maybe the murky fuel is on the bottom of the tank, and one fuel pickup is longer than the other?
Someone else thought that maybe a hose is old and starting to break down and cause the murky fuel? It was sitting for about 5 years with normal unleaded
 
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