Engine problem - '85 Mercruiser 170

[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.

[scook]

Hah - Spare, I think you nailed it. I got the boat in '05 because it was doing exactly what it's doing now - ran 20 minutes and died. We changed the fuel line ant it ran OK.

The guy who owned it before me was a complete non-mechanic (knew how to change the oil and that was it). He had lots of money and when he got frustrated with the V-20, he went out and spent $65k on a new 23' Striper WA and told me later that the V was a better boat in the ocean.

They were only going to give him $1700 trade-in for the boat and trailer and he said "no, I love my old boat and I'm not giving it away to a dealer". My daughter did some work for him and got the boat for me for my birthday with the assurance it was going to a good home. I've done a lot of work on it, but I see why he loved his old boat.

[spareparts]

just replaced fuel lines on a 2008 Intrepid 25 today. It needed it.

[scook]

Do I need to use USCG approved, below deck fuel line, either because it is required or because it is safer than automotive line? I haven't checked automotive pricing but the approved stuff is around $6/ foot at West Marine.