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Old 11-22-2005, 08:41 AM   #1
shelby987
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dieseling?

what causes it....and whats the best way to fix it.....I am sitting at a 50/50 rate here.....half of the time its fine, and half of the time it runs for 10 secs. after I shut the engine off.....sometimes it sputters a couple of times, revs real high, then dies.....any ideas?
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Old 11-22-2005, 08:44 AM   #2
truckdude239
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Re: dieseling?

timeing out?
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Old 11-22-2005, 08:46 AM   #3
larry may
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Re: dieseling?

Set the idle down a bit. When they idle too fast they will do this. Noticed this more with stock engines. Camed up some not so likely to act as such.
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Old 11-22-2005, 08:50 AM   #4
76bonanza
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Re: dieseling?

mine was from the return spring not pulling the throttle closed everytime.
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Old 11-22-2005, 11:27 AM   #5
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Re: dieseling?

The most common reason I see is the throttle plate is too far open at idle. Try re-tuning the carb. It maybe a little rich at idle which requires the throttle plate to be open more than it should be in order to run. Check the timing before you re-tune. I also had a problem with my high-idle not kicking down all the way. This can cause the same problem.
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Old 11-22-2005, 12:00 PM   #6
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Re: dieseling?

I had a catch in my throttle linkage that made it seem like it was closed, but really wasn't. Solved this, and re-set my timing. Everything was better.

Running-on is usually caused by a hot spot developed in one or more cylinders that continues to ingite fuel after you've turned off the ingition. If there is fuel and air still available the engine will run-on. By closing the carb all the way you eliminate the air from the equation. Poor timing can cause a hot spot to develop.

Rochester used to have a soliniod that held the throttle open when driving, but let it close all the way when the car was off. I've seen them for holleys too.

Untill you get it fixed, you can turn off the engine while it is in drive, then shift to park after.

more later
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Old 11-22-2005, 12:13 PM   #7
shelby987
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Re: dieseling?

its a stick shift, so that probably won't work all that well.

Can anyone tell me what the correct timing for a stock 250 is?
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1969 SS 350 Camaro Sold 2008
1970 3/4T K20, stock height with 33's, 250 I6, 3 on the tree, and locked front and rear 4.10's
1980 Chevy Malibu 2 dr Sold 2007
1993 Olds. Cutlass Ciera Wagon Traded 2006
2003 Saturn L200 w/5pd. D/D
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Old 11-22-2005, 08:01 PM   #8
muddpile
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Re: dieseling?

I advanced the timing and set the idle down a bit on mine. It runs better now and no dieseling. Its a 350 with a Q-jet.
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Old 11-23-2005, 02:10 PM   #9
68speedalert
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Re: dieseling?

The 6 cyls had a idle stop solenoid. It will extend whenever the key is on. It has to work and be adjusted right to stop the dieseling. There is a allen screw in the top of it. If I remember right, you screw the entire solenoid to set the engine idling speed, Then disconnect the wire to it and adjust the solenoid off speed with the allen head. If the specs aren't on the fender (yeah, right) let me know and I will find them.

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Old 11-23-2005, 02:11 PM   #10
gringoloco
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Re: dieseling?

What he said. Lower your idle, allowing the throttle plates to fully close when you shut off the engine. Bump up the timing a little to regain your idle quality. If that doesn't do it, check for vaccum leaks; its gotta be getting air somewhere...
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