Logo
FULL SITE MENU

Fuel in Oil Problem

C

capnjim

New member
"I have a 1986 Chris Craft Cat

"I have a 1986 Chris Craft Catalina 381 with twin Mercruiser MIE 340's (454 GM block). On my first run after launch this year, ran for about 1/2 hour when the starboard engine oil pressure dropped and the engine quit as I was docking. I checked the oil and found a huge amount of fuel in the oil. I also noticed fuel leaking into the bilge from the forward part of the engine. I closed two fuel shut off valves to stop the leakage. I have drained the oil and fuel from the crankcase and removed the oil filter. I removed over 5 gallons of oil/fuel mixture from the engine. My thought is that the fuel pump diaphragm failed. Is there anything else in the fuel system that could cause that much fuel to get into the oil? Should I be looking beyond the pump? I appreciate any advice you can give.

Capnjim}}"
 
"If it is mechanical fuel pump

"If it is mechanical fuel pump, I'd say you're likely on the bubble with your diagnosis. Not sure if there is any other way for fuel to get into the oil in that kind of quantity.
Could you tell from where the fuel was leaking at the front of the engine?
For the cost of a fuel pump, and the peace of mind, since they may be 20+ years old, I would replace them both, just on spec.
My brother has twin Crusader 454's in a 36 foot Ultraflite, and he is just in the midst of having them changed over to electric fuel pumps and updated filters, mainly for peace of mind."
 
"Yes, it is a mechanical pump.

"Yes, it is a mechanical pump. The fuel ran down the main water hose from the seawater pump, which is right below the fuel pump. But, I didn't see or feel it coming from the pump. I will probably change the other pump soon. Thanks for your help."
 
Back
Top