# 91 Chevy S10 Blazer idles but wont accelerate



## jarjarb65 (Apr 27, 2008)

I have a 91 Chevy S10 Blazer with a 4.3 Litre W (CPI) code engine. I know the 91 was supposed to only be available with the Z (throttle body) code engine, but the W motor is in my truck. The VIN says Z, but when you hook up a scanner ant tell it Z it says the vehicle isnt communicating. When you tell the scanner W it works fine. My problem with this thing is sometimes it starts and idles but wont accelerate. When experiencing the problem, the truck idles slightly rough. When you try to gas it, it doesnt stall but starts bogging, like it's running out of gas. If I lean harder on the throttle, It will start popping slightly through the intake, but never stall. I've had a fuel pressure gauge on it and fuel pressure is in spec, I've had the map sensor and TPS tested, both good. I've tried disconnecting the battery to clear the computer, it worked once but not this time. I just got this thing about a month ago and it did this to me on the second day I had it, but it was to cold and crappy out to work on it. Most lt it runs great. Any suggestions? Scott


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## Raylo (Feb 12, 2006)

Might be an intermittently sticky EGR. Sounds like what happened once to my 1994 W engine S10 p/u. If it sticks open at idle (when it should be shut) the motor will buck, pop, etc, and seem to have no power. In my case I didn't have any codes because the valve was sticking open mechanically and the EGR system was otherwise getting the correct control signals.


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## jarjarb65 (Apr 27, 2008)

That's the first time anybody's made that suggestion. I'll definately check that out when it stops raining here. Thanks.


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## RIGHTE0US (Jan 7, 2008)

also if you have a fuel pressure guage available (i see you stated you tested the pressure) try testing it with the truck running and you giving it gas..shouldnt fluxuate much, if it does, pump may be getting weak


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## Whitetail Crazy (Apr 30, 2008)

Had a 88 pick up with TBI and would do this type of thing. Pop and backfire when hitting the accelerator. Started as somewhat intermitent but progressed to be a real problem. Found the ground bad at the thermostat housing. I cleaned the stud and put a new end on the ground wires. Problem solved. Just another quick and easy check....
PS had no codes.


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