engine not cutting off

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

I have a 1995 200Horizon . I have been having a problem with the engine not cutting off when I turn the switch off. I have replaced the ignition switch but that did not seem to help. It seems to happen most when I run the boat for a while at about 3/4 throttle It doesnt happen all the time Any suggestions would be greatly appreciated

gregs · **Posted:** Thu Jun 21, 2012 8:54 am

So the engine stays running as it normally does, or is it running on or "dieseling" when you shut it off. How do you stop it when it does this.

What engine?

ric · **Posted:** Thu Jun 21, 2012 9:16 am

So when you turn the key off, it kinda runs rough on it's own? That's what we call "dieseling". Carb jetting is too lean. This could also be due to ignition timing being off. Verify it with a timing light. Did you recently start using E10? It burns slower/leaner then E0 and the engine will need adjustment.

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

It is a 5.0 Cobra EFI The only way that I have been able to turn off is to run it a little longer with the switch off or if I am docked I have to rev it up until it finally shuts off . It sounds like maybe a fuel problem but I think it should still cut off with the switch off or the kill switch pulled neither one works. I have tried running premium (super) fuel but no luck

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

It does run rough a little but most of the time it will just shut off after a couple minutes Im not sure I khow how to check timing

Sanmiam · **Joined:** Sat Mar 24, 2012 9:05 pm **Posts:** 84

Ethanol causing dieseling? That's new. Where is the spark coming from if this is the case?

Most likely cause is carbon build-up (heats up and provides a source of ignition) or timing too advanced. Check timing, and run SeaFoam (or my personal favorite, BG44) through your next tank of gas. That should knock all the crap out and hopefully get rid of the source of ignition and therefore the dieseling.

Don't wait on this - the dieseling can burn a valve if left too long.

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

I have heard about SeaFoam but have not tried it I will try it and let you know

ric · **Posted:** Thu Jun 21, 2012 6:05 pm

Sanmiam wrote:

Ethanol causing dieseling? That's new. Where is the spark coming from if this is the case?

Most likely cause is carbon build-up (heats up and provides a source of ignition) or timing too advanced. Check timing, and run SeaFoam (or my personal favorite, BG44) through your next tank of gas. That should knock all the crap out and hopefully get rid of the source of ignition and therefore the dieseling.

Don't wait on this - the dieseling can burn a valve if left too long.

E10 runs leaner. If it was already a factory lean tune to begin with... E10 will run really lean and get the spark plug hot enough to keep firing with no spark. A carb has a bowl of fuel that can go for a while.

Dieseling with FI? Most likely carbon on pistons. Start using E10 to clean it out

Aussie_Horizon_190 · **Posted:** Thu Jun 21, 2012 6:07 pm

Mine does this all the time on regular uinleaded and has done since day 1. Switched over to premium gas and the problem goes away completely.

ric · **Posted:** Thu Jun 21, 2012 6:26 pm

Aussie_Horizon_190 wrote:

Mine does this all the time on regular uinleaded and has done since day 1. Switched over to premium gas and the problem goes away completely.

You might want to go up a jet size on the carb, takes minutes it's just a holley carb. You're running slower burning fuel (premium) to offset the effects of running hot/lean. Water temp isn't reflecting this but if I bet if you took CHT readings it would be off the chart. Not especially good for head gaskets.

vipergg · **Joined:** Tue Jun 12, 2012 8:24 pm **Posts:** 29

Make sure you are running 89 octane and use something like Startron in every tank and this will minimze dieseling .

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

Do you think running one tank of fuel with additives should fix problem if not I will take to shop to get timing checked. Plan on trying it out tomorrow with SeaFoam Thanks for all the info

Borchik · **Posted:** Fri Jun 22, 2012 12:16 pm

Is it dieseling or is it just running normally for a short period of time after you shut the key off? From what I am gathering when you say it runs for a couple minutes then shuts off that is not dieseling.

newbie · **Joined:** Wed Jun 20, 2012 8:52 pm **Posts:** 10

It does not diesel it just shuts off after a little while (1 - 2 minutes) Sometimes it will miss a little when I run around 3/4 throttle but runs great anything less ???? Im headed to the lake in a bit to try the seafoam I put in last night If you have any suggestions Im all ears

ric · **Posted:** Fri Jun 22, 2012 12:37 pm

See if a buddy has a timing light. Check it. To verify and how to check timing just google search how to check the timing on a 1986 mustang 5.0 gt

www.iFourWinns.com

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