IF EITHER THE UPPER OR LOWER INTAKE GASKET WERE LEAKING?

1995 Chevrolet Blazer

Tiny

sjbambrgr8

March, 19, 2012 AT 12:49 AM

On a 1995 s-10 blazer would it cause it to run rich? It is a 4.3 motor I replaced the long block in my 1995 s-10 blazer with one from a wrecking yard. The motor runs but runs rough at idle and surges. I have checked all the vacuum lines, replaced the fuel regulator, replaced the cap, rotor, and spark plugs. I get no check DTC or FF codes.

CE light will come on and flash occasionally but will go off while driving it. I had just done head gaskets on the old long block and replaced all the gaskets so when I pulled off the intake all the gaskets looked good so I re-used them (probably not the best thing to do but anyway.). Vacuum is running low, around 15 in. I have checked timing. There is no washing in lower intake when I pull the plenum off. I spray with starting fluid around the manifold when it is running and it doesn't "smooth" out.

When I spray starting fluid directly into the air cleaner it makes the motor run worse, in part probably because it is already running rich.

Hopefully you can help me.

6 Answers

Tiny

fixitmr

March, 19, 2012 AT 1:07 AM

Spider injection? Maybe some poppets are sticking.

Tiny

sjbambrgr8

March, 19, 2012 AT 1:23 AM

When I pull all the spark plugs they are all showing rich condition. It would be pretty coincidental for all the poppets to go bad at the same time I replace the long block wouldn't it? They were all fine with the old motor.

Tiny

sjbambrgr8

March, 19, 2012 AT 1:24 AM

Also, I pulled the EGR valve in there was nothing blocking it. It has a gasket with a screen on it and the screen was clean. I pulled the map sensor and cleaned it for good measure although like I said the old motor ran fine with all these same components.

Tiny

fixitmr

March, 19, 2012 AT 1:30 AM

Maybe you missed a ground wire somewhere? But funny thing is, I got an old cheby 2.8 MPFI that I put new intake gaskets on and it's doing the same thing. Running way too rich. Havnt had time to dic wit it cause it's a 4th car.

Tiny

sjbambrgr8

March, 19, 2012 AT 1:36 AM

No missed ground wires. They have a bold on the back of each head that is grounded and one at the base of the block by the crank that is a ground wire. This is the 4th motor I have replaced in a blazer and this is the first time I have had this issue. This is also the first time I have reused gaskets.

Tiny

fixitmr

March, 19, 2012 AT 1:51 AM

Iv'e re-used gaskets from time to time but I always coat them with copper gasket sealer spray coating.

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