I am a mechanic working with back yard tools. 1994 S10 blazer 4.3 cpi, ran fine and then began to lose power to the point that it idles fine but will only throttle to about 2000rpms in park and wont even pull itself under load. Checked all throttle components, good. removed catalytic converter, no change. Problem is throughout cold and warm running conditions which I figured ruled out O2 sensor and temp sensor. Any idea what I could check next? No backfire except when shut off it seems to puff out throttle body but not bad.

 

Did you check the air cleaner for restrictions? If that's ok, it sounds like it either jumped time, or you have some worn camshaft lobes.

 

Thx for reply! It was running with air cleaner removed due to past front damage. It was cut off with air temp sensor still in place but I noticed top of vapor canister is broken. Is their a way to bypass vapor box to rule it out as a problem? The problem all happened within a week. The engine does not miss! just wont throttle up. was reading up on ECT system and sounds like a knock sensor could retard timing. what are the chances? wouldnt it miss or backfire or something like that??

 

Plugged cat could be your issue.

 

already removed cat! How about 1 injector isnt there only 2 on the cpi? It is quite hard to get to on this setup!

*Combining Consecutive Posts*

Also wanted to mention that I did a fuel pressure test and it seemed to maintain 52psi on idle and 50psi under acceleration.


*EDIT by swartlkk* - Please use the EDIT feature to add additional information to your post. Consecutive posting is prohibited by the rules of the forum.

 

Also wanted to mention that I did a fuel pressure test and it seemed to maintain 52psi on idle and 50psi under acceleration.

 

As far as vacuum leaks are concerned, just plug the lines. If the vapor canister has been damaged, just disconnect and plug all of the vacuum lines at the canister. Do not do this permanently as it can cause a check engine light and possibly driveability concerns.

 

Thx for info! That is what I thought so that is what I did, still no change in problem!! Thinking something along the line of timing advance but not sure where to start. I guess I will hook up light and start messing with knock sensor and any related items to timing advance but would still appreciate suggestions.

 

Have you tested the ICM & coil?

 

Fuel filter? Sometimes the easiest fix is the cause. Even though you have good pressure at idle and revving up the engine sitting still, there is no load on the engine.