Engine runs after ignition off (1 Viewer)

[OhioFJ]

Greetings all,

This 40 has an original 2F engine and a rebuilt aisin carb that I believe is from 1982 (marked 2G21 and a sticker that says "factory remanufactured by Holley"). I've had it for about a week so I'm very much still sorting it out. Overall is seems to run well. Has trouble maintaining idle before its warmed up, but once driven for a bit is ok. Oddly, I've noted that after a drive the engine will run roughly for 1-3 seconds after turning off the ignition.

Any thoughts on where to start?

 

[Jonathan Hanson]

You are experiencing "dieseling," so-called because it refers to ignition caused by residual heat in the combustion chamber rather than spark. It can be caused by carbon buildup that retains heat, or some other hot spot. It typically occurs in gasoline engines with high mileage. It can be cured by removing the head and finding the issue, or in some cases by installing a solenoid that positively cuts off fuel flow when the ignition is turned off. I haven't heard of anyone doing this in some time but it might still be possible. Your carb might have one; I can't remember if all factory carbs did.

 

[1FastBimmer]

check your plugs, my 76 was dieseling bad when I bought it because the PO installed an electric pump way up on the firewall that was berely pulling fuel, engine ran lean and died at times, and cyl 5,6 was burning so much oil that the plugs had tons of buildup causing about 10 seconds of bad dieseling when hot.

 

[OhioFJ]

Interesting, thank you - I have some new plugs on the way as a first step.

 

[ceylonfj40nut]

Make sure your fuel cut off solenoid is working properly as well.

 

[pjohnson]

Check your timing and adjust the valve lash also. It's most likely a combination of things.

 

[OhioFJ]

Think seafoam is worth a try?

 

[Dizzy]

Gotta check the fuel cut solenoid, spark plugs for fresh oil.

 

[duncanrm]

If you have an electric radiator fan.. this can cause run on when it shuts off if its poorly wired... it turns from a fan into a generator as it runs down.

 

[Steamer]

I'll be the 3rd to say check the fuel cut-off solenoid. It's mounted on the carb and could be as simple as a loose wire. You should hear it click when the key is turned to "run". To hear it better, leave key on then disconnect and re-connect repetitively, the wire going to the carb.

Lots of opinions on SeaFoam. Myself and a few friends have had positive results with it. The method I like is pouriing 2/3 of the can down the carb at very high idle and pouring it slow enough to keep it from stalling. After 2/3 are in, quickly dump in the rest to make it stall. Let it sit 20-30 minutes then start it up to clear it out. It'll put out out one hell of a smoke screen so take note of wind direction where you do it.

 

[Coolerman]

Greetings all,

This 40 has an original 2F engine and a rebuilt aisin carb that I believe is from 1982 (marked 2G21 and a sticker that says "factory remanufactured by Holley").

Any thoughts on where to start?

Remanufactured by Holley??? Might want to show us a pic of this carb...

 

[OhioFJ]

Remanufactured by Holley??? Might want to show us a pic of this carb...

yeah I thought it was odd too. Any insight appreciated

 

[OhioFJ]

Sorry about the picture orientation - they’re correct on my phone but get rotated when uploaded

 

[Coolerman]

OK that sure looks like the correct carb for an 82. Had no idea Holly was into rebuild Aisin carbs though!
So yeah like everyone has mentioned, check that the idle solenoid is working. You should hear it "click" when the key is turned on.

 

[4x4veteran]

Does it give knocking sound with the run on? If not , could be to fast an idle.
Set idle back a bit and or adjust the idle air screws.

 

[OhioFJ]

OK that sure looks like the correct carb for an 82. Had no idea Holly was into rebuild Aisin carbs though!
So yeah like everyone has mentioned, check that the idle solenoid is working. You should hear it "click" when the key is turned on.

Thank you - will try that tonight

 

[OhioFJ]

Does it give knocking sound with the run on? If not , could be to fast an idle.
Set idle back a bit and or adjust the idle air screws.

No knocking that I can hear. It’s not idling that well when cold so I was planning of tinkering with that too

 

[OhioFJ]

I can hear the idle solenoid clicking when I power it - still worth taking it apart to clean it?

 

[pjohnson]

I would do a thorough tune-up and reset everything to OEM specs. I bet the problem goes away.