4.3L Mercruiser Keeps Running after switched off

[livingwater]

I have a problem where the engine seems to keep running for a few seconds before it shuts off 5-10 secs after turning off ignition.<br />This is after running it for a while.<br />Any help fo a newbie????

 

[SteveNix]

Re: 4.3L Mercruiser Keeps Running after switched off

need a little more info there:year, make, some more specifics, but if the engine is carbed, my guess would be that its dieseling. <br />does it kind of sputter until it dies?

 

[Mischief Managed]

Re: 4.3L Mercruiser Keeps Running after switched off

Carbureted 4.3s are notorious for this. <br /><br />Some tips:<br /><br />Let it idle for a few minutes after a high speed run before shutting it down. This cools down the heads.<br /> <br />Try shutting it of in gear<br /><br />Run a tank full of Chevron "Techron" treated gasoline through it and then run the lowest octane fuel that won't cause pinging or run-on. I say this becuase high octane fuel tends to leave deposits in the combustion chambers and on intake valves. These combustion chamber deposits can be the cause of the run on. Failing that...<br /><br />Run higher octane fuel

 

[KaGee]

Re: 4.3L Mercruiser Keeps Running after switched off

You may want to check out the timing. If it's too far advanced that could cause it.

 

[WillyBWright]

Re: 4.3L Mercruiser Keeps Running after switched off

High idle can do it. Low octane gas can do it. Timing too advanced can do it. First thing to check is the idle RPM. The spec should be available, but I believe it's 650 in gear in the water. If that doesn't help, retard the timing 2 degrees.

 

[Bt Doctur]

Re: 4.3L Mercruiser Keeps Running after switched off

running a "high temp" will affect it too.

 

[livingwater]

Re: 4.3L Mercruiser Keeps Running after switched off

You guys are brilliant for help, much appreciated.<br /><br />It is a 2001 carburetted 4.3L<br />It only does it occassionally when wakeboarding.<br />It just seems to splutter will it dies.<br />I will check timing. I do run the highest octane fuel we can get at Australian gas pumps. <br />If these 4.3L are notoripous for this then maybe I have nothing to worry about. and will try and let it idle a little before shutdown.<br /><br />Thanks again for so much help