Hi everybody i'm new here, Just trying to find out whats wrong with my Grandpa's 1996 Blazer.
It will run fine when it's first started up and run on a short trip, but if it gets run for about 10 miles continously it will stall out. Then if it sits for a little while it will start back up. I checked the computer codes and none were displayed. I also hooked up a fuel pressure gauge and drove it around until it stalled. When running normally it read at about 55 psi. When it was being drivin it would read about 50-60psi. When it was about to stall the motor would hesitate and the fuel pressure gage would jump around. When it stalled the pressure would drop to 40psi. No matter how much i cycled the key on and off the pressure would not go above 45 psi. After I let is set a while I would turn the key on and the pressure would shoot right up to 60 psi and fire right up.
I was thinking it would be the fuel pump but that was replaced about 2 yrs ago. I also heard some stuff about the fuel pressure regulator but i'm not sure if that's it.
Has anyone else had this problem?

 

I just had this issue on a Saturn last week. Dont ignore the fuel system, but a lot of people are getting results from changing the crank position sensor. You wouldnt think about it because its not throwing a code, but apparently these things are failing like crazy and not being picked up by the PCM. It was the same exact symptoms too. Would start initially, then die shortly after and not restart until about at least an hour or so. Then would start again fine, then die and so on.

 

Follow through the steps in this thread to narrow down the problem.

96+ Fuel System Diagnosis

 

There's your problem. Anything below 60psi will start to affect performance. Below 55psi it needs a manual shot of fuel in the throttle body to start. At 45psi it will barely run, and probably not accelerate. Below 40psi the poppets will not squirt fuel and the engine will not run. Key on, engine off, fuel pump running, the fuel pressure must be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off.

The fuel pressure regulator is either good or bad, they're not intermittent. Very simple part and rarely fails.

Make sure the pump is getting battery voltage and has a good ground. If those are ok, stick an AC Delco pump in there and be done!

 

Ya I was thinkin that it had to be somthing electrical. Let me guess i gotta drop the tank to get to the connector?

 

Unfortunately, yes, unless you have really skinny, long arms.