Engine run-on

[LFK]

After heavy use (pulling kids on a tube, etc) if I shut my engine off (to pick up the kid I just tossed off the tube) my engine sputters through a few more revolutions. Does this mean I need to use a higher octane fuel? I just put the cheap stuff in it, what do you guys use?

It's a 1989 3.7L Merc. Alpha One (Does this mean it's a Ford?)

Sputter, sputter, cough....

More importantly than what causes it, is it a problem or just an annoyance?

 

[mcleaves]

Re: Engine run-on

It's a problem because when that happens the eninge is actually runing backwards at times and instead of pushing exhaust out it's going to act as a pump and pull WATER in.

You need to correct it. I'm sure others will chime in with the HOW.

M

 

[Kevin70]

Re: Engine run-on

When was the last time you had a tune up and set the timing? This can happen when the timing is off enough to heat up the pistons and those red hot pistons continue to ignite the fuel in the chamber.

 

[LFK]

Re: Engine run-on

When was the last time you had a tune up and set the timing? This can happen when the timing is off enough to heat up the pistons and those red hot pistons continue to ignite the fuel in the chamber.

Just a couple months back. It's my first boat and I had it professionally winterized and then again prepped and tuned for the summer season.

It doesn't happen all of the time, only after I've been making it work for a while.

 

[Fishermark]

Re: Engine run-on

This is a common issue, and in fact I believe Mercruiser even issued a bulletin on it a while back. Basically the only way to keep it from happening, (assuming your timing is right, etc), is to let it idle a couple of minutes before shutting it off after an extended, hard use.

 

[LFK]

Re: Engine run-on

Thanks. Guess I'll just have the kids tread water away from the transom for a minute or two before shutting down for them to get back in.

 

[Don S]

Re: Engine run-on

Here is a link to the Mercruiser service bulletin.

http://www.boatfix.com/merc/Bullet/97/97_17.pdf

In my experience, the two most common reasons are high idle (over 750 rpm) and not allowing the engine to idle for a minute or two after a run, and pulling a tuber or skier for a minute or two is a hard run.

 

[Kevin70]

Re: Engine run-on

I heard that treading water is great exercise for kids.dd

 

[LFK]

Re: Engine run-on

I heard that treading water is great exercise for kids.dd

No doubt! I might even have to tell them that it takes 15-20 minutes for it to cool down. :devil:

 

[LFK]

Re: Engine run-on

Here is a link to the Mercruiser service bulletin.

http://www.boatfix.com/merc/Bullet/97/97_17.pdf

In my experience, the two most common reasons are high idle (over 750 rpm) and not allowing the engine to idle for a minute or two after a run, and pulling a tuber or skier for a minute or two is a hard run.

Thanks for the link! That's exactly what's happening.