IF EITHER THE UPPER OR LOWER INTAKE GASKET WERE LEAKING?

  • Tiny
  • sjbambrgr8
  • 1995 Chevrolet Blazer
  • 160,000 miles

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.

Monday, March 19th, 2012 AT 12:49 AM

6 Answers

  • Tiny
  • fixitmr
  • Member

Spider injection? Maybe some poppets are sticking.

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Monday, March 19th, 2012 AT 1:07 AM
  • Tiny
  • sjbambrgr8
  • Member

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.

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Monday, March 19th, 2012 AT 1:23 AM
  • Tiny
  • sjbambrgr8
  • Member

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.

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Monday, March 19th, 2012 AT 1:24 AM
  • Tiny
  • fixitmr
  • Member

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.

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Monday, March 19th, 2012 AT 1:30 AM
  • Tiny
  • sjbambrgr8
  • Member

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.

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Monday, March 19th, 2012 AT 1:36 AM
  • Tiny
  • fixitmr
  • Member

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

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Monday, March 19th, 2012 AT 1:51 AM

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