Mercruiser Running Problem

[Sea'Scape]

I have a 1997 Mercruiser 4.3 LX Gen + that I am having some trouble with. The long story follows so that I don't miss anything that might be pertinent.

Went out and engine temperature alarm went off. Throttled down and let engine cool. Tried again and temp started to build as I increased RPMs. Problem was diagnosed as barnacles in cooling tube in leg. Leg was cleaned out and impeller replaced. Temp stays around 160 now. This probably is not related to the problem I am still having.

Put the boat on plane and the engine died. Restarted easily and ran well until I increased RPM and tried to put boat on plane when engine died again. I could run at speeds below planing speed.

Pulled boat and took it into the shop where the following was done;
- fuel filter was checked and showed no sign of water
- plugs were replaced
- tune up kit was installed

Engine was rune in tank at 3200 RPM for a period and no problem showed up.

Took the boat out and ran it. A couple of times over the evening I felt the engine power fade briefly and heard what I can best describe as a "cough". This would occur shortly after a start up. The it would seem to not happen again and I ran for a half hour without it happening again. It may happen more often but I didn't put the time on the engine to see.

I'm trying to run the fuel down so I can fill with fresh fuel. Would any fuel additive possibly help.

The problem at the moment doesn't happen with sufficient predictibilti and frequency to bring the mechanic out and take him for a run.

Suggestions would be appreciated.

 

[Rocky_Road]

Re: Mercruiser Running Problem

Forget adding any fuel additives to your existing load...except for, maybe, a can of Sea Foam (that stuff can cure cancer!).

You are right to be thinking 'fresh fuel'...and get into the habit of using an ethanol formula (Sta-Bil, Startron) AT the gas pump! E-10 gas has increased the "help me" posts in here, a hundred fold....

 

[Sea'Scape]

Re: Mercruiser Running Problem

Thanks RR. I'll see if I can locate a can of SeaFoam treatment and add it to my fuel. I'm in British Columbia so need to find someone that stocks it up here.

In the meantime I'll keep running the tank down so that I can get as much fresh fuel in as possible.

Cheers.

 

[Rocky_Road]

Re: Mercruiser Running Problem

Thanks RR. I'll see if I can locate a can of SeaFoam treatment and add it to my fuel. I'm in British Columbia so need to find someone that stocks it up here.

In the meantime I'll keep running the tank down so that I can get as much fresh fuel in as possible.

Cheers.

I had no idea that you were from outside the USA! Are you using ethanol spiked fuel...like we are?

If not...forget my suggestion to start adding ethanol formula fuel stabilizer, and focus on using any decent stabilizer that you can get your hands on! If you have trouble finding Sea Foam for your current issue, I have no problem mailing you a can, if it is legal to do so....

Happy boating!