Engine problem - '85 Mercruiser 170

[bradford]

Agree with Smoke. Sounds like fuel and possibly water in the fuel.

[spareparts]

does your oil smell like gas? Could be a bad fuel pump leaking gas into the engine, that will make your oil pressure very low and at teh same time cause a fuel delivery issue.

[THEFERMANATOR]

Originally Posted by spareparts

does your oil smell like gas? Could be a bad fuel pump leaking gas into the engine, that will make your oil pressure very low and at teh same time cause a fuel delivery issue.

This is what I was thinking as well. Neighbor went through this on his 4.3L. They didn't put but a small filter after the pump, and it quickly plugged up with rubber from the pump. His carb plugged up, engine would barely idle, and his oil pressure dropped like a rock after a gallon of gas went into the crankcase.

[scook]

I'll do some oil sniffing. Probably should change the fuel water separator filter to be sure it's not water (the tank is full so shouldn't be condensing moisture). I wouldn't think it would start and run great for 20 minutes if the carb was clogged up - this is the second time it's done this. Was leaning toward ignition since it's the only thing that's changed but will work the fuel issues first.

Thanks

[steplift20]

Keeping it simple
A engine needs three things to run
Air
Oil
Gas
I would start there check to make sure all those things are good
Just my 2 cents
I could get lucky sometimes, but definitely check your water separator The gas they sell today is not hood e 10

[scook]

Don't forget spark.

Yeah, I agree - need to check for gas in the oil and address all fuel issues. At the beginning of the season, I emptied the tank thoroughly, drove a few extra miles and filled up with non-ethanol gas and thought this was going to be a trouble free season. 30 year old boat, I guess I've got to expect an occasional problem, but I'd rather it wasn't during fishing season.

[spareparts]

also, if they haven't been replaced recently, replace all your fuel lines, I've been doing that on boats only 5 years old to fix issues. This new fuel whether E or non-E is tough on rubber lines.