My 94 s10 blazer 4x4 vin w has had a rough idle for about 3 weeks now, I have changed plugs, wires, vacuum lines, IAC, TPS, and also cleaned the EGR out and put a new gasket with screen on it and still it has a rough idle but it has gotten a little better, anyone have any other ideas as to what it could be. Thanks.

 

Read out codes, engine light or not.

Disconnect all lines to the vacuum ports and plug the ports.
check for better

Disconnect the harness connector to the iac and start engine
run unlit propane torch around all intake manifold mating surfaces.

 

No codes.

I'm lying, I just went out and read codes after going to store, 22, 32, 34, 54.

Okay after disconnecting the battery then hooking it back u the truck won't run unless I hold the gas pedal down.

Well I think there is something wrong with the gas pedal cable going to the throttle under the hood, if I pull the slack out of it and tie it off with a zip tie the truck will stay running, any ideas cause I'm about to put this thing in the lake.

 

Slack?? Where? Everything hooked up and running good, the thing should run with throttle on the stop. Should be no slack. Do not adjust that screw, though.

Need picture.

 

I'm at work and can't upload pictures at this time, but it won't run with the throttle on the stop.

 

sometimes cleaning the EGR will not solve the problem if it is sticking open due to age and wear and tear, the last time this happened to me I had to replace the EGR. just food for thought.

 

Okay I figured out how to upload a pic from my phone.

I was gonna change out injectors tomorrow thinking that's what my problem was but now I'm not so sure I should do that. Truck is driving me nuts.

Stopped at autozone on the way home and rented a fuel pressure tester and hooked it up, with key on engine off the pressure would come upto 50 then drop back down after a few seconds, with the engine running it would stay at 50 steady until I shut it off then drop right back down after a few seconds.

 

found your problem. Fuel pumps bad. It needs 60 psi minimum to run.



time to replace pump. Buy ONLY ac delco or delphi....or else you will be back in it soon. im speaking that from everyone on here...brands do make a difference in pumps for these blazers.

 

Is the fuel pump simple to change? My Haynes manual doesn't really go into detail.

 

Changing the pump is simple getting to it is not. You have to remove the gas tank to get access to the top of the tank to remove the Fuel Pump Assy. The fuel pump assy. is held secure by a lock ring. Use a screw driver and a hammer to tap the lock ring. Remove the whole assy. and then replace the pump on the assy. The fuel pump is attached with hose clamps and has an electrical connector. Once everthing is off replacing the pump is very straight forward. The consensus on this forum is to stick with either AC Delco or Delphi brand fuel pumps because they are proven reliable and long lasting. The last thing you want to do is to have to do this job again due to a premature pump failure. You can buy just the pump or the whole fuel pump assy.