Issue turning off ignition

[Mick65]

When I turn off my 65 C10 it continues to run for a few more seconds before turning off. It almost acts like when a diesel turns off. Does anybody know what could cause this?

[DesertCat]

Need a lot more info about the problem, history of how it runs, history of any recent changes, what is stock and what is custom.....

But here's a quick stab in the dark - Do you have an alternator on it? Improperly wired alternators can feed back to the ignition circuit.

Timing?

carb clean, properly adjusted?

[kerber63]

Do you have an electric fan? When I originally installed my dual setup they would keep the motor running for a few seconds after the ignition shut off. Because they would be turning when the power shut off, they acted as a weak alternator and fed the engine with power until they stopped spinning. A cheap diode from RadioShack fixed the problem.

[Mick65]

The timing is definitely off and needs to be sorted. I do have an electric fan. Thanks guys. I'll take a look at these

[Sharps40]

Couple common possibilities.

Carb out of adjustment/something not functioning in the idle circuit of the carb.

Fouled spark plugs, valves or pistons causeing a hot spot.

Timeing off.

Feedback as mentioned from electric fans, hei, alternator or other devices plugged into the wrong spot.

My vote is for carb issues or timeing.

[shawno72]

Timing to advanced or retarded?

[ky-donzi]

x2 on the fans had it happen on a truck i had, unhook them and try it... If i remember correctly it depends on where they get there power from if they can back feed the ing circuit. Seems like the problem was traced to hooking the fans directly to the fuse panel... Seems like the fix we used was a relay that killed with the key switch.

[forestb]

Mine was doing the same thing a while back ago. If it is not the timing check for a vacuum leak.

[tincan1966]

In order to help fix- have to know what it is doing. Is it dieseling or is it not shutting off?

If it's dieseling, then check timing, idle speed and for a vacuum leak as mentioned. If it just doesn't shut off(keeps running normally) then you most likely have a feedback of the alternator, as posted earlier.

[Mick65]

I took it to a shop today to get it timed and the mechanic (whos a genius) and he said that it was my electric fan giving feedback. I'm going to get this fixed on monday. Thanks for everybodys help

[61_FL_Apache]

Sounds like an easy fix!

[ChrisDollins]

Just wondering if this fixed your issue or not. My 250 is doing the same thing, just recently got worse after installing pdb/ps. But it also has been hotter outside too. Turn the key off and it sputters for about 5 seconds or more. No electric fan, engine runs and starts great. Factory single barrel carb rebuilt about 4 years ago. Don't know what temp the engine is running just yet, only have the lights right now. Thanks for any help.
Chris
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[1restorick]

Trying removing the Generator light bulb. My truck did this after installing an MSD ignition. Only it would never shut off period and the generator lamp was lit with the key in the off position.A diode installed in this lamp circuit solved the problem. Good luck.

[ChrisDollins]

Oh ok. Wonder if the msd had anything to do with it? Mine still has points. It definitely isn't "running" just hitting a couple of times and sounds like a crappy movie car fabricated sound lol. Embarrassing...

Chris
Posted via Mobile Device

[1restorick]

Mine had everything to do with the MSD. They even give you the diode with the MSD box. What is interesting is that I have installed several MDS ignitions over the years in many older cars and my truck was the first vehicle that needed the diode to stop the back feed.

[ChrisDollins]

Ok, starting to think its temperature related. Because we just took it around the yard (little guy loves riding in the truck) and it shut off perfectly.

Chris
Posted via Mobile Device

[hotrodder]

Had the same problem it was the electric fan feeding back for a few seconds.