I have a 95 blazer that I need running since my primary vehicle (89 corsica) blew a rod bearing. The truck has 171,000 miles on it. I've redone all of the top end gaskets and entire exhaust. It has a rough idle to it and backfires at idle. The plugs, wires, cap+rotor have been replaced. It seems to me that its getting too much fuel, so I tested the fuel pressure. My results were that it gets about 60psi from the pump with the key on. The manual says that its supposed to drop to about 10psi once the truck is at idle, but mine stays at 60psi! Fuel pressure regulator? Those damn spider injectors maybe? I need this thing running properly before the snow falls.

Any help or suggestions would be very helpful.

Thanks

 

Other than the back fire, I had the same symptoms. Take a look at your O2 sensors. If you re-did the exhaust, and all the the distributer components, that would be the last part I had a problem with for a similar issue.

As for your fuel pressure, for your year, I think 56-60 was the norm.

 

I replaced the O2 sensor by the Cat. Is there one thats hidden up by the headers?

 

What does your fuel pressure do once the pump shuts off (engine off)? That is what is being referred to as the 10psi drop.

 

It still says that the pressure is at 60psi, but then again my pressure tester doesn't have a depressurizing button on it. I still can't get over the backfire issue though. My timing is as on as it can be, my ignition parts are brand new, I'm thinking that my EGR could be toast.

 

I talked to a mechanic in my extended family, he thinks that something in the valve train is worn, broke, or loose. I went and tightened everything down and now it won't even start. I'm really close to saying goodbye to this piece.

 

What did you tighten down..?

 

I re-torqued all of the rocker arms. I also checked the pushrods to see if they were bent.

 

Update on the Blazer. I am pretty sure the person who helped me correct the timing on it the first time didn't know what the hell he was talking about. I noticed that there are two notches on the harmonic balancer. I know that one of these stand for Top Dead Center and Bottom Dead Center. Which is which? Thanks guys. Appreciate the help.

 

If your cap has the horizontal towers, use the 96+ Engine Timing procedure in the Tech Article (DIY) section.