engine sputters for up to a minute after ignition is turned of

[Olegb]

i have 99 4.3l volvo penta carborated and when the ignition is turned of the engine still sputters eventually stops any ideas what this is from and how to fix it

 

[Eric 3.7LX Alpha 1]

Re: engine sputters for up to a minute after ignition is turned of

Very low octane/bad gas?

 

[Don S]

Re: engine sputters for up to a minute after ignition is turned of

i have 99 4.3l volvo penta carborated and when the ignition is turned of the engine still sputters eventually stops any ideas what this is from and how to fix it

DO NOT allow that to continue that long. It can suck water back through the exhaust and hydrolock your engine.

It's called dieseling or running on. Most common cause is to high an idle rpm. your engine should be idleing at 650 to 700 rpm. Next most common reason is after a hard run, just shutting it off. Let it idle for a minute or two to cool down and clear the gas out of the cylinders and with a proper idle speed, the engine will shut off like it should.

 

[OldNBold51]

Re: engine sputters for up to a minute after ignition is turned of

Carbon buildup on the valves and piston top is also often one of the causes. These buildups retain heat (think little charcoals) and this heat will trigger leftover fuel/air in the intake system to fire w/o the need for spark.

Much better gas with cleaning additives coupled with bottled cleaning additives help fix this.

I know there is much controversy about these so called "snake oils" but for this purpose, they do a pretty decent job.

Sea Foam is one of the best. Techron works well also.