I have a 1997 Chevy Blazer, 4WD, 4.3L V6 With Central Port Fuel Injection. It won't start so I checked the fuel pressure. the book says that it should be between 58-64psi with the ignition on but engine not running. When I check mine, it is at 56 - 58 psi. It would look like it is the fuel pump, but it starts at 62 then drops to 56 after 2 seconds and the pump stops pumping. I use to check fuel delivery systems on older cars by putting a gas soaked rag in the intake pipe, but with all of the electronic sensors on a car now is it still possible to get the engine to fire for a second or two when the fuel systems is not sending fuel to the injectors? How would I check that it is the pump and not the fuel regulator when its not running?

Thanks,
Frank

 

I did some more checking on the fuel problem tonight and it will pump up to 62 psi with the key on for 2-3 seconds then the pump stops and the pressure drops to 56-58psi. I then waited about 2-3 minutes and the pressure had dropped to 50psi. Would that prevent the engine from starting? I tried to spray starting fluid into the intake (removed the intake tube so mass flow sensor was not on the intake) and it bogged down when I tried to start. It's like it was too rich or something and not firing. After about 10 seconds of turning over very slowly it would start spinning fast like it had not back pressure. I'm confused.

Frank

 

Your truck uses the newer SCFI (sequential central fuel injection) system which has six individual electronic injectors located in a central injection body with each electronic injector feeding a pressure actuated poppet nozzle located at the intake ports.

If you do not have the incoming air flowing through the MAF sensor, you may not get it to run even in perfect working order. To do away with that problem, disconnect the MAF sensor until you have the intake piping all hooked up.

And on the fuel pressure, well, it sounds like you have a leak somewhere in the system.

Leak locations are as follows:
[ol][*]Fuel Pump Check Valve (test by removing the fuel filter and installing a fuel pressure gauge on the line to the tank)[*]External Fuel Lines (very obvious)[*]Leaking Fuel Pressure Regulator (requires pulling the upper intake manifold off and reinstalling the upper fuel lines to pressurize the system)[*]Leaking Electronic Injector (with the upper plenum off and the system pressurized, pull each poppet nozzle out of the lower intake one at a time and see if any of them are leaking)[/ol]

That should cover it.

 

Thanks for the info. I checked the fuel pump at the fuel filter and it check fine. I then replaced the fuel filter and double checked the spark, compression, replaced the spark plugs. that didn't work so I double checked the distributor timing and it matched where the book said it should be when at TDC on #1. So I connected the compression gauge and set the spark plug next to it. I held down the pressure release button on the gage and turned over the engine. The spark seemed to be a little early so I reset the distributor again and it fired!! Now all i have to do is button up the other loose ends and I can road test it this weekend.

Thanks for you help.
Frank