88 Blazer S-10 4.3 T.B.I. auto 4x4 219,000 miles
Hi all, small prob, The factory temp gauge stopped working and after replacing the sender three times the gauge still did not work. I decided to replace it with a manual one that goes directly unto the block in the same place the factory sender was, so l know what the temp is, as old is this truck is I felt more comfortable. Now I have a prob that was not there before the replacement. The running temp is 190-195, it has 195 degree thermostat. Ok an example of the prob is when I stop and go into a store and turn it off, as you know the temp will rise somewhat, say to 200 or 205 degrees just after I turn it off. When I come back and crank it and start on my way it starts stumbling around like it is trying to vapor-lock, I back off the throttle and ease back into it and it clears up. As long as I am driving around there is no prob, but when I let it idle for long periods or shut it off the prob comes back. I taped and isolated the old wires to the sender so it could not short out to the block, So the old sender wires are not connected to anything. I wonder if this is a prob with the computer that I don't have the temp sender wires connected to anything. I would appreciate any help that you guys can give me. Thank You

 

That vintage of S10 4.3 uses (2) temperature senders, One for the gauge (on passenger side cylinder head between two front cylinders - single wire) and One for the engine computer (on top of engine behind thermostat - 2 wire)

Depending on which one you removed/disconnected, you may be confusing the computer.

 

Yea make SURE you changed the one on the passenger side,above the exhaust manifold and not the one beside the rad hose. rad hose one is for the computer,one on the sides for temp gauge

 

I did replace the one on the passenger side below. So that means no computer mixup then? Thanks

 

Maybe the problem just came along while doing all this. Remove the Iac valve on the passenger side of the tbi unit. its a round sensor which is screwed in sideways. Black square plug. remove it,clean the piston with brake cleaner,as well as inside the hole with a toothbrush. it controls idle. See if that helps.

 

the iac valve is number 250

Light Truck Chevrolet 1989 S10 BLAZER 4WD FUEL SYSTEM-EXHAUST-EMISSION SYSTEM 1985-1990 ST THROTTLE BODY INJECTION/SINGLE INJECTOR (MODEL 700)(LN8/2.5E) Car parts for your Buick, Cadillac, Chevrolet, Hummer, Light Truck, Oldsmobile, Pontiac, and mor

 

Thank You guys. I will now check the IAC valve and clean it. I will let you know what happens,
Thanks Again

 

hi, i did check out the two temp sensors, the one up top is connected and does have two wires, but the one below that was connected to the gauge sensor also has two wires. I am wondering that is is possible that this truck came that way. The engine was replaced before I got it so now maybe things have changed from stock. Thanks for your help, maybe you have another suggestion.

 

Thanks for the info guys, replaced iac, problem fixed.