86 350 Won't run - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sapmap · 10-10-2003, 12:41 PM

Hey thanks for the PCV info.
Fortunately down here in the South we ain’t go to worry about emissions, no smog checks here.

I’ve got a 81 GMC Sierra ½ Ton, with a 1986 350, HEI ignition, Rochester Q-jet M2ME, The other morning when I tried to start it, it was running really rough, once it got warm it seemed to be ok, but the next day it got worse….and so on until it wouldn’t even stay running, during this time, it was smoking a lot when I would accelerate, (Black smoke), When I crank it If I keep pumping it, it will stay running but just barely.
I have replaced all ignition components ( I was planning to do this anyway). But the problem didn’t go away, Its got to be the carb. I am thinking.
Its got good compression on all 8. Since I had to pull to dist. To replace the pick-up coil I have it static timed at 6 deg. Btdc, I can’t keep it running long enough to set the timing.
Any suggestions would be welcome.

Prerunner1982 · 10-10-2003, 12:49 PM

try your choke.. and about the PCV, whether you have emissions or not. you still need the PCV!

sapmap · 10-10-2003, 12:51 PM

I made a mistake on the carb, its a M4ME

**old Rusty C10** · 10-10-2003, 05:52 PM

i had a problem like that with my 4.3 with the quadrajet now i had a PVC valve but im wondring if the carb is the problem, mine went through a rebuild which did little to help the problem cause the electric pump sensor ( not sure of its correct name) was the problem. I swapped out a different one and alls well now
hope that helps

crackajacka · 10-12-2003, 12:05 AM

have u tried adjusting the carb? theres 2 adjustment screws at the base on both corners, you'll need to pick up an adjustment tool to adjust those

gchemist · 10-12-2003, 02:55 AM

You have the same problem as chevychic. The colder weather is affecting the operation of the carb. Set your choke to stay closed longer. I have the same problem. Once my truck reaches its operating temp of 180+ is runs okay.

85 K5 · 10-12-2003, 07:00 AM

Filled up with gas the other day, Blazer started idling rough, bad cat converter smell. Results of finding the best gas price. Next tank all was ok.

Mike76251 · 10-12-2003, 08:59 AM

If you have a black electrical plug going into the top of that carb. then you have a "electronic" Q-Jet.
It has a mixture control soleniod under that plug and they often go out and cause the type of problems you are describing.

I would fix it by putting on a Holley 650 Vac. secondary.

10-10-2003, 12:41 PM	#1
sapmap Registered User Join Date: Oct 2003 Posts: 4	86 350 Won't run Hey thanks for the PCV info. Fortunately down here in the South we ain’t go to worry about emissions, no smog checks here. I’ve got a 81 GMC Sierra ½ Ton, with a 1986 350, HEI ignition, Rochester Q-jet M2ME, The other morning when I tried to start it, it was running really rough, once it got warm it seemed to be ok, but the next day it got worse….and so on until it wouldn’t even stay running, during this time, it was smoking a lot when I would accelerate, (Black smoke), When I crank it If I keep pumping it, it will stay running but just barely. I have replaced all ignition components ( I was planning to do this anyway). But the problem didn’t go away, Its got to be the carb. I am thinking. Its got good compression on all 8. Since I had to pull to dist. To replace the pick-up coil I have it static timed at 6 deg. Btdc, I can’t keep it running long enough to set the timing. Any suggestions would be welcome.

10-10-2003, 12:49 PM	#2
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,906	try your choke.. and about the PCV, whether you have emissions or not. you still need the PCV! __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

10-10-2003, 12:51 PM	#3
sapmap Registered User Join Date: Oct 2003 Posts: 4	carb is a M4ME not a M2ME I made a mistake on the carb, its a M4ME

10-10-2003, 05:52 PM	#4
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,300	i had a problem like that with my 4.3 with the quadrajet now i had a PVC valve but im wondring if the carb is the problem, mine went through a rebuild which did little to help the problem cause the electric pump sensor ( not sure of its correct name) was the problem. I swapped out a different one and alls well now hope that helps __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

10-12-2003, 12:05 AM	#5
crackajacka Stylin Join Date: Sep 2001 Location: Tuttle, OK Posts: 620	have u tried adjusting the carb? theres 2 adjustment screws at the base on both corners, you'll need to pick up an adjustment tool to adjust those __________________ Ive been traveling for some time, with my fishin pole and my bottle of shyne. Most Girls like finished products and just dont understand what a good addiction does for you http://www.paulwall.us/

10-12-2003, 02:55 AM	#6
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	You have the same problem as chevychic. The colder weather is affecting the operation of the carb. Set your choke to stay closed longer. I have the same problem. Once my truck reaches its operating temp of 180+ is runs okay. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

10-12-2003, 07:00 AM	#7
85 K5 Registered User Join Date: Nov 2002 Location: Spring TX Posts: 113	Filled up with gas the other day, Blazer started idling rough, bad cat converter smell. Results of finding the best gas price. Next tank all was ok. __________________ 350 Crate 10 bolt 3.73 2.5 lift 32x11.50 1904 Edelbrock http://www.oplnk.net/~spirit/K5front.jpg

10-12-2003, 08:59 AM	#8
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,500	If you have a black electrical plug going into the top of that carb. then you have a "electronic" Q-Jet. It has a mixture control soleniod under that plug and they often go out and cause the type of problems you are describing. I would fix it by putting on a Holley 650 Vac. secondary.



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