'85 Chevy carb problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

westcasey · 09-29-2004, 09:03 PM

I've got an '85 Chevy 3/4 ton 4x4. It has the same engine in it as the Corvettes had that year. I've had the dang thing in the shop several times because I don't know anything about carbs. It soots up the spark plugs really bad about a week after replacing them. I've had the carb rebuilt and adjusted 3 times by two completely differnt shops. It still does the same thing..... soots the plugs up and misses really bad. Can anyone help me out? NO BODY can seem to get this dang thing to run right. It ran perfect until one of my employees ran the thing out of oil and I had to replace the engine!!!

**swervin ervin** · 09-29-2004, 10:06 PM

Not knowing for sure, but it sounds like you have a computer controlled carb on it since you say it's the same engines Corvettes had in 85. If this is the case, you will never get it to run right without the computer. What happened to the carb that was on the stock engine?

westcasey · 09-29-2004, 10:37 PM

This is the same carb. I don't think it is controlled by the computer. The only electrical wire running to it is going to the choke. It is the same engine as the corvettes that year; I checked that out with the local dealership.

76HighSierra · 09-29-2004, 11:26 PM

Are you sure that you don't have an oil-fouling problem?

westcasey · 09-30-2004, 08:56 AM

I don't know what you mean by an oil fouling problem.

76HighSierra · 09-30-2004, 10:09 AM

I mean are you sure it's not oil fouling the plugs instead of unburnt fuel?

westcasey · 09-30-2004, 12:51 PM

I don't know. What are some signs to look for? It blows black smoke, which I assume is from the dirty spark plugs not burning all the fuel off. What would cause the oil to foul the plugs?

hilbilly · 09-30-2004, 02:16 PM

Just a note, but are you sure the plugs are the correct heat range?

westcasey · 10-03-2004, 08:54 PM

What would cause the oil to foul the plugs?

1987SierraClassic · 10-03-2004, 09:19 PM

If it's blowing black smoke, it's running too rich....
Does it run poorly through the whole temperature range or just warm?
Is the replacement engine identical to the one you took out? If not, perhaps it's too much carb for it. The carb may be setup for the higher performance engine. You may have to re-jet the carb if that is the case...

Just a thought...

09-29-2004, 09:03 PM	#1
westcasey Registered User Join Date: Jan 2004 Location: kansas Posts: 49	'85 Chevy carb problems I've got an '85 Chevy 3/4 ton 4x4. It has the same engine in it as the Corvettes had that year. I've had the dang thing in the shop several times because I don't know anything about carbs. It soots up the spark plugs really bad about a week after replacing them. I've had the carb rebuilt and adjusted 3 times by two completely differnt shops. It still does the same thing..... soots the plugs up and misses really bad. Can anyone help me out? NO BODY can seem to get this dang thing to run right. It ran perfect until one of my employees ran the thing out of oil and I had to replace the engine!!! __________________ 1987 GMC 1500 5.7L 1985 Chevy 3/4 4X4 2001 Chevy 2500 HD 4X4 2007 Chevy 3500 Duramax 4X4

09-29-2004, 10:06 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Not knowing for sure, but it sounds like you have a computer controlled carb on it since you say it's the same engines Corvettes had in 85. If this is the case, you will never get it to run right without the computer. What happened to the carb that was on the stock engine? __________________ Mike 1985 Chevy C-10

09-29-2004, 10:37 PM	#3
westcasey Registered User Join Date: Jan 2004 Location: kansas Posts: 49	This is the same carb. I don't think it is controlled by the computer. The only electrical wire running to it is going to the choke. It is the same engine as the corvettes that year; I checked that out with the local dealership. __________________ 1987 GMC 1500 5.7L 1985 Chevy 3/4 4X4 2001 Chevy 2500 HD 4X4 2007 Chevy 3500 Duramax 4X4

09-29-2004, 11:26 PM	#4
76HighSierra DAMN, I love Big Blocks! Join Date: Aug 2003 Location: New Mexico, USA Posts: 619	Are you sure that you don't have an oil-fouling problem? __________________ Marc Bona Hobbs, New Mexico 1976 1/2 ton GMC High Sierra. 454 c.i.d./ TH400. *Soon to get a mild warming over.* 3.40 rear.

09-30-2004, 08:56 AM	#5
westcasey Registered User Join Date: Jan 2004 Location: kansas Posts: 49	I don't know what you mean by an oil fouling problem. __________________ 1987 GMC 1500 5.7L 1985 Chevy 3/4 4X4 2001 Chevy 2500 HD 4X4 2007 Chevy 3500 Duramax 4X4

09-30-2004, 10:09 AM	#6
76HighSierra DAMN, I love Big Blocks! Join Date: Aug 2003 Location: New Mexico, USA Posts: 619	I mean are you sure it's not oil fouling the plugs instead of unburnt fuel? __________________ Marc Bona Hobbs, New Mexico 1976 1/2 ton GMC High Sierra. 454 c.i.d./ TH400. *Soon to get a mild warming over.* 3.40 rear.

09-30-2004, 12:51 PM	#7
westcasey Registered User Join Date: Jan 2004 Location: kansas Posts: 49	I don't know. What are some signs to look for? It blows black smoke, which I assume is from the dirty spark plugs not burning all the fuel off. What would cause the oil to foul the plugs? __________________ 1987 GMC 1500 5.7L 1985 Chevy 3/4 4X4 2001 Chevy 2500 HD 4X4 2007 Chevy 3500 Duramax 4X4

09-30-2004, 02:16 PM	#8
hilbilly I do everything twice, so what Join Date: Mar 2004 Location: To the Right. One may go as far to say WAY to the Right Posts: 378	Just a note, but are you sure the plugs are the correct heat range?

10-03-2004, 08:54 PM	#9
westcasey Registered User Join Date: Jan 2004 Location: kansas Posts: 49	What would cause the oil to foul the plugs? __________________ 1987 GMC 1500 5.7L 1985 Chevy 3/4 4X4 2001 Chevy 2500 HD 4X4 2007 Chevy 3500 Duramax 4X4

10-03-2004, 09:19 PM	#10
1987SierraClassic Registered User Join Date: Sep 2004 Location: Buxton, ME Posts: 91	If it's blowing black smoke, it's running too rich.... Does it run poorly through the whole temperature range or just warm? Is the replacement engine identical to the one you took out? If not, perhaps it's too much carb for it. The carb may be setup for the higher performance engine. You may have to re-jet the carb if that is the case... Just a thought...



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