250ci Desiels when shut off - The 1947 - Present Chevrolet & GMC Truck Message Board Network

threeonthetree · 05-20-2010, 09:04 AM

my truck seems to desiel after a drive im wondering what would cause it to do this? its seeming to get worse the more i drive it around town.

Hair · 05-20-2010, 09:49 AM

Mine was doing the exact same thing. It would desiel after I turned it off.
I don't know what caused it, maybe someone will come on and know.

Anyway, I pulled my motor out to put new gaskets and clean it up and paint it. In the process, I put in a new timing chain, an HEI distributor, and a new carb. Now it doesn't do that anymore. I know this aint much help, but one of those things fixed it.

Whatever it may be I think it is timing related and all you got is a dizzy and a timing chain. Start by making sure your timing is set correctly (didn't help me).

Oh, if you give up on trying to fix it, like I did, just turn your truck off in gear and that will prevent it from doing that. After its off be sure to stick it in Park LOL.

Hair · 05-20-2010, 09:51 AM

Wait a minute... if your's is a straight shift scratch the "cutting it off in gear" comment. LOL

milled · 05-20-2010, 10:24 AM

buy diffferent gas..... also that can be caused by a carbon hotspot on the head... try slowly pouring a cup of water in a hot running motor with the rpm around 2200rpm.... it'll clean it out nicely. tru the carb

geezer#99 · 05-20-2010, 10:36 AM

Your idle is too high. Slow the motor down. Deisiling is caused by a hot spot in the intake mixed with a little fuel and a bit too much air created by the throttle blades being a little to far open. Idle her down a bit.

70clone · 05-20-2010, 10:50 AM

Its usually causeD by carbon build up that is still red hot like coal in a grill when you shut it off as long as the motor rotates there is still fuel and air being pullEd into the combustion chamber. I have found that the best thing for this is seafoam crank ur truck and slowly pour 1/3 of the bottle into the intake then shut the truck off and let it sit for 15-30 min then crank it and just watch the smoke come pouring out the tail pipe thats smoke is all ur carbon buildup goin bye bye.

292farmer · 05-20-2010, 08:52 PM

my old 350 (i know not a 6) did that because it was still hot and the float level was off and was dripping fuel into intake. try checking float level then maybe do a carb rebuild.

hayhauler71 · 05-21-2010, 11:00 PM

Quote:

Originally Posted by geezer#99

Your idle is too high. Slow the motor down. Deisiling is caused by a hot spot in the intake mixed with a little fuel and a bit too much air created by the throttle blades being a little to far open. Idle her down a bit.

This is one of the most common to cause your run on.

mclairmo · 05-21-2010, 11:39 PM

Too high idle speed is common cause but carbon build up on the valves or in combustion chamber can also cause it. I like to use a can of BG44K in the gas tank to clean that crap out, works real good. I can find it at my local Toyota dealership for like $20 a can.

beautimus · 05-22-2010, 01:40 AM

you might try the easy stuff first, like using a can of aerosol type carb and choke cleaner to make sure that gunk buildup isn't blocking the throttle and choke butterflys partially open. if nothing else itll make the carb look cleaner, and its cheap!
good luck

05-20-2010, 09:04 AM	#1
threeonthetree Registered User Join Date: Feb 2009 Location: Wausau, WI Posts: 975	250ci Desiels when shut off my truck seems to desiel after a drive im wondering what would cause it to do this? its seeming to get worse the more i drive it around town. __________________ Smoking Tires Since 1992 1969 c10 AKA SIN 1985 SSWB TRAZER (super short wheel base)

05-20-2010, 09:49 AM	#2
Hair Registered User Join Date: Mar 2008 Location: Tullahoma, TN Posts: 406	Re: 250ci Desiels when shut off Mine was doing the exact same thing. It would desiel after I turned it off. I don't know what caused it, maybe someone will come on and know. Anyway, I pulled my motor out to put new gaskets and clean it up and paint it. In the process, I put in a new timing chain, an HEI distributor, and a new carb. Now it doesn't do that anymore. I know this aint much help, but one of those things fixed it. Whatever it may be I think it is timing related and all you got is a dizzy and a timing chain. Start by making sure your timing is set correctly (didn't help me). Oh, if you give up on trying to fix it, like I did, just turn your truck off in gear and that will prevent it from doing that. After its off be sure to stick it in Park LOL.

05-20-2010, 09:51 AM	#3
Hair Registered User Join Date: Mar 2008 Location: Tullahoma, TN Posts: 406	Re: 250ci Desiels when shut off Wait a minute... if your's is a straight shift scratch the "cutting it off in gear" comment. LOL

05-20-2010, 10:24 AM	#4
milled Registered User Join Date: Feb 2008 Location: arvada colorado Posts: 105	Re: 250ci Desiels when shut off buy diffferent gas..... also that can be caused by a carbon hotspot on the head... try slowly pouring a cup of water in a hot running motor with the rpm around 2200rpm.... it'll clean it out nicely. tru the carb __________________ 1970 k20 350 4speed hd44 14b Circumventing the language filter is against site rules Last edited by milled; 05-20-2010 at 10:25 AM.

05-20-2010, 10:36 AM	#5
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,707	Re: 250ci Desiels when shut off Your idle is too high. Slow the motor down. Deisiling is caused by a hot spot in the intake mixed with a little fuel and a bit too much air created by the throttle blades being a little to far open. Idle her down a bit.

05-20-2010, 10:50 AM	#6
70clone Registered User Join Date: Oct 2006 Location: JACKSONVILLE FL Posts: 200	Re: 250ci Desiels when shut off Its usually causeD by carbon build up that is still red hot like coal in a grill when you shut it off as long as the motor rotates there is still fuel and air being pullEd into the combustion chamber. I have found that the best thing for this is seafoam crank ur truck and slowly pour 1/3 of the bottle into the intake then shut the truck off and let it sit for 15-30 min then crank it and just watch the smoke come pouring out the tail pipe thats smoke is all ur carbon buildup goin bye bye. Last edited by 70clone; 05-20-2010 at 10:51 AM.

05-20-2010, 08:52 PM	#7
292farmer Registered User Join Date: Nov 2009 Location: stoddard nh Posts: 693	Re: 250ci Desiels when shut off my old 350 (i know not a 6) did that because it was still hot and the float level was off and was dripping fuel into intake. try checking float level then maybe do a carb rebuild.

05-21-2010, 11:39 PM	#9
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: 250ci Desiels when shut off Too high idle speed is common cause but carbon build up on the valves or in combustion chamber can also cause it. I like to use a can of BG44K in the gas tank to clean that crap out, works real good. I can find it at my local Toyota dealership for like $20 a can.

05-22-2010, 01:40 AM	#10
beautimus Registered User Join Date: Mar 2002 Location: woodstock, alabama, usa Posts: 938	Re: 250ci Desiels when shut off you might try the easy stuff first, like using a can of aerosol type carb and choke cleaner to make sure that gunk buildup isn't blocking the throttle and choke butterflys partially open. if nothing else itll make the carb look cleaner, and its cheap! good luck __________________ i survived cancer and kidney stones, but my kids are killing me.



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