motor turns over a couple more times after shut off?

[Mattys1970C-10]

this happens about once every couple times I drive it. when I turn the key off, the truck turns over a couple more times like its tryin to stay on and then dies. what is this from?

[wreckedchevy]

far as I know it's usually cause the timing is slightly off. mine's doing it now as well just haven't had a chance to put a timing light on it.

[jmj4]

the term for it is dieseling, also known as engine run-on. you can google it and find gobs of info.

[Lee H]

Run-on is almost always cause by the idle being to high.

[kwmech]

Timing cranked up too high, vacuum leak, idle adjusted too high.....

[Mattys1970C-10]

The truck bogs when I stomp it from a idle, could this be related? once it gets past the bog it runs like a raped ape

[68gmsee]

Originally Posted by Mattys1970C-10

The truck bogs when I stomp it from a idle, could this be related? once it gets past the bog it runs like a raped ape

Possibly. Double check your timing initial and total. I use manifold vacuum (below the butterflies) on my trucks. Also check the vacuum advance to make sure it's not leaking and moves easily with mouth suction if you don't have a suction pump. And check the idle air adjustment for max vacuum.

In the past when I've had dieseling problems, I always throw in one or two cans of fuel treatment like Chevron. I usually do it every fill up until it stops. Had good luck like that. I had to do it on my Ranger work truck three times and haven't had any problems for 3, 4 years.

[Chris04]

It's your timing sounds like to me

[wreckedchevy]

got my timing sorted out tonight (and found my vacuum advance no longer functions) but the dieseling stopped. the distributer was a little loose and moved itself to about 20deg set it back to 10

[Mattys1970C-10]

i dont have a timing light....ill have to find someone who does

[68gmsee]

Originally Posted by Mattys1970C-10

i dont have a timing light....ill have to find someone who does

There are a few tools us old truck owners need that we don't use often but should have. My short list (besides regular wrenches and socket sets) include a timing light, vacuum gauge, volt/ohm meter and feeler gauge. There are others but these are the more important ones.

I find it always a hassle to borrow tools since these days most people don't do their own work on these new vehicles. And, if money is tight, buy one at a time.

[msgdsrf]

Dieseling and bog into transition is definetly idle set too high, opening the blades into the transition slot. Timing does not effect engine run.

More initial timing will allow you to bring the idle back to where it belongs. More intial timing will also allow the idle to burn better keeping the heads cooler if that is the issue but not likely since you also mention the bog.

[Mattys1970C-10]

so what is "more initial timing"? ive always had EFI hot rods so I dont understand this. I adjusted the timing in my blown mustang with a switch in the glove box for race fuel

[msgdsrf]

You need a timing light. Check timing with engine at operating temp and disconnect distributor advance from vacuum hose (plug hose from carb). This is your initial timing.

You could just try rotating distributor about an 1/8" counter clockwise, which will then raise your idle. Now lower the idle back down at the carb with idle screw. See how she acts with this adjustment. If starter drags, it's too much counter clock rotation.

[Mattys1970C-10]

which one is the idle screw?

[1972RedNeck]

Originally Posted by wreckedchevy

far as I know it's usually cause the timing is slightly off. mine's doing it now as well just haven't had a chance to put a timing light on it.

How could timing affect it? as soon as the key is shut off, there is no spark to be timed.

[msgdsrf]

Originally Posted by Mattys1970C-10

which one is the idle screw?

You being serious? As in which screw in the engine bay? Have you looked at your carburetor? At the end of the throttle(gas pedal) rod, there's a lever and a screw attached to that, back it off to lower idle. Go as low as you can run it with an auto transmission in gear. This is all a bit DIY, and if you're not comfortable in that area you may want to find someone that is. Though I have never found any competent mechanics that can do more than read an OBD port.

[msgdsrf]

Originally Posted by 1972redneck

how could timing affect it? As soon as the key is shut off, there is no spark to be timed.

100%.

[68gmsee]

Originally Posted by Mattys1970C-10

which one is the idle screw?

Depends on the carb you have. A pic would help.

The idle speed screw is the one that increases or decreases the idle speed on the engine. Idle air screws are the ones usually at the base front of carb and are used to adjust the idle air mixture for maximum vacuum.

[Mattys1970C-10]

its an edelbrock 600 electric choke. ill give this a try and see how it goes

[Mattys1970C-10]

Originally Posted by msgdsrf

You being serious? As in which screw in the engine bay? Have you looked at your carburetor? At the end of the throttle(gas pedal) rod, there's a lever and a screw attached to that, back it off to lower idle. Go as low as you can run it with an auto transmission in gear. This is all a bit DIY, and if you're not comfortable in that area you may want to find someone that is. Though I have never found any competent mechanics that can do more than read an OBD port.

yes totally serious, never owned a carb'ed vehicle in my life and my carb has two adjustment looking screws on the front so i didnt want to adjust the wrong one and make this worse. I figure if I tighten the e-brake cable and disconnect the horn this whole problem will be fixed. hell while im at it ill shave some weight by removing one lug nut per wheel.....ass, thanks for the help lol

[Lee H]

Your next purchase needs to be a service manual.

[davischevy]

Hang in there Matty. I've been working on these things for fifty years and still have to ask what screw from time to time? I'd say everybody on this board has had the "dieseling" problem at one time or another, and it can be hard to sort out. It's usually a combination of things, and ethanol doesn't help.

As said before, vacuum, idle air settings, idle speed, and timing. Lots of combinations, and a lot of it is by ear.