7 replies to this topic

[viking1978]

Hey all-I own a 2005 SSi with a Volvo 4.3. I just purchased the boat last Labor Day, and only had it in the water a few times. But the few times I had it in, whenever I would turn the key off, the motor would run-on or diesel. I have had people tell me it's a timing problem, and others say it's a carb problem. Any help would be appreciated. Thanks...

[PAT]

Try a colder spark plug or a higher octane gas first.

[Firemedic555]

What octane are you running now ?

[Shepherd]

Could also try idling the engine for say 20 seconds before turning it off, especially if you're pulling a tube or water skiers, etc. Hot spots on the cylinders combined with a carb set-up and tightened emissions can make for some frustrating times with run-on, aka dieseling.

As others have said, try switching to a high octane fuel first.

If none of the above tricks work, then the engine timing and carb set-up will have to be checked, along with possibly going with a colder range thermostat, and mayhap colder range spark plugs.

[viking1978]

I run regular unleaded, which I believe is 89 octane. I will try these suggestions when I get her back in the water next month. Thanks everyone for your input.

[professor48]

Many marinas and gas docks only carry high test and diesel because that covers most boat engines. If you're trailering, you have other options. First, try upgrading to 91 octane. That may solve your problem, simply because today's gasoline is not the same as gasoline was seven years ago. Good luck. Hy

[Pops]

Or look for a vacuum leak somewhere on the intake. What is your idle speed? If too high, that'll do it too.

[Texascrew]

My 5.0 did the same thing the first few times out. I think it was just old gas in the tank from the previous owner. After a few top offs, it hasn't done it since. I never did get the tank very low, so I still had a little bit of old fuel every time I filled it up. The ONLY problem I've had with a "fuel efficient" V-8 powered boat is that it never used enough fuel on a weekend to get the old gas out.