'95 Blazer no start

[dac675]

This one has really got me stumped, so I am hoping one of the GM Techs (or someone who has had a similar problem) may have some ideas.

 

I have a '95 Blazer with the 4.3 "W" engine. It began to run rough and then would not restart. Since I had a decent amount of timing chain slop and low compression (about 100 PSI all around), I did the chain. The compression is now around 140 all around. I had also done plugs, a cap and rotor, and filters at the same time. Still no start. Fuel pressure was leaking down and a little weeping from the spider nozzles, so I changed the CPFI injector (including nut kit and harness leads which were in poor condition). Fuel pressure now builds and holds to about 55 prestart, and stays there while cranking. Still no start. A couple of drops of fuel in the intake or a small shot of starting fluid, and it will start and run like a champ (nice and smooth, no power problems). But it will not start in its own (exception - if it has just been running, it will start up while it is still hot, but otherwise, nothing). Changed the crankshaft pos sensor in the HVS. Still the same. Even swapped in a computer (same serv #) from a firend's S10. Even with the other computer, it does the same thing! I am going crazy trying to figure this one out! I wuld do the crank sensor, but I am getting a good spark (and from what I have read, a bad crank sensor would knock out spark as well). Also, the computer is not throwing any codes! Even after it runs (or cracks without running, nothing.

 

Please help! My sanity is on the line here. I cannot imagine what it is that is keeping the truck from starting on its own. Any ideas or thoughts would be greatly appreciated.

[95Sierra2500]

what's your fuel pressure before startup? I'm betting it's your fuel pump. Had this same problem on my fiancee`'s 99 Jimmy.

[wct]

what's your fuel pressure before startup? I'm betting it's your fuel pump. Had this same problem on my fiancee`'s 99 Jimmy.

 

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I would have to agree leave a fuel pressure gauge on over night or how ever long it takes to not start, check fuel pressure before you turn the key on then turn the key on and see what fuel pessure reads it needs to be @ least 55psi, the popit valves in the injectors need at least that much pressure to open 54 it won't run. You may also want to dead head the pump use a vice grip and slightly pinch the return line under vehical while some one cranks the engine and monitor the gauge NOTE: don't try this on plasic or meatle lines only on hoses

[95Sierra2500]

what's your fuel pressure before startup? I'm betting it's your fuel pump. Had this same problem on my fiancee`'s 99 Jimmy.

 

<{POST_SNAPBACK}>

 

 

 

 

I would have to agree leave a fuel pressure gauge on over night or how ever long it takes to not start, check fuel pressure before you turn the key on then turn the key on and see what fuel pessure reads it needs to be @ least 55psi, the popit valves in the injectors need at least that much pressure to open 54 it won't run. You may also want to dead head the pump use a vice grip and slightly pinch the return line under vehical while some one cranks the engine and monitor the gauge NOTE: don't try this on plasic or meatle lines only on hoses

 

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I thought it was 65 PSI to start, 55 to keep running...that's what I was told, anyway...and if it's not at 65 or more, it won't start.

[dac675]

Thanks guys. It was the fuel pump. I put a newer gauge on it and only showed 51 PSI. Changed the pump and now it is closer to 60. Started right up!.

 

Thanks for all of the input. I wish I had known sooner (I think I killed an otherwise good fuel injector). Oh well - live and learn.

 

Thanks tyo all who posted.