I have a 97 4 dr. 4x4 blazer I have replaced the pump, plug and wires. I've also replaced the pressure regulator but still when I do a leakdown test I get 60-65 psi but as soon as I shut off the key or when the pump times out it immediately the pressure drops to 40psi. it runs like crap has no power cel just flashes at me which I know is a misfire code. I've pulled all the injectors out of there bore and none seam to be leaking. also I've replaced the roll over valve on the front of the tank because the first time I removed the tank I broke it. I've tested the pump righat after the fuel filter and I have 60-65 pam there but does not bleed down anyhelp from this point would be very appreciative.I don't wanna spend the $ for injectors if its not gonna fix the problem. I have a very good level of mechaanical skill so if there are any tests to do please let me know

 

Your leakdown to 40psi is a problem. When checking pressure at the fuel filter connection, all pressure and flow must end at the tester. This checks the maximum output pressure, and the pumps ability to hold pressure. Pressure must be 73psi to 108psi and it must remain above 55psi for at least 10 minutes after the pump shuts off. If it passes both parts of the test, the excessive leakdown problem is in the plenum.

EDIT: If you just Tee'd the tester in at the fuel filter, you're checking regulated fuel pressure, (same as at the service port next to the distributor). The results of that test will not tell you the condition of the fuel pump.

 

you have a misfire?
have you checked or ever replace your distributer cap and rotor?

 

Yes captain I did not tee it st the fuel filter I put rubber hose on the outlet of the filter so the tester was at the end not tee fitting. I've replaced the pump and sane results only 60-65 psi at the filter
I do know that I need to replace the cap and rotor but I wanted to get the fuel pressure problem fixed first

 

I've also pulled out my injectors from there bore and they do not appear to be leaking. And the pressure regulator is new but I'm wondering if its bad as it might be sending the fuel back to the tank instead of holding pressure

 

let me start off saying the only reason I've changed the pump the first time is because the gauge didn't work ( but run just fine) and it all went downhill from there so far in the past 6 months I've owned it I drove it 3 days. I really like driving it but not the way its acting up

 

60psi to 65psi is not enough pressure for the regulator to work, much less supply the engine with enough fuel to run properly. Unplug the fuel pump module connector and check resistance on both black wires at the connector. Both must show less than 5 ohms to ground. Turn the ignition ON and check voltage on the grey wire. It should show battery voltage for ~2 seconds then drop to zero, post your results.

 

On the pump side of the connector or the vehicle side.( I'm guessing at the pump) I put the pump back in that the blazer came with because it ran fine when I bought it but do u think s pump would go bad that quick?

 

Gotta check resistance & voltage on the vehicle harness when it's unplugged from the fuel pump module.

Could be a problem with voltage and or ground to the pump making both pumps do the same thing. A poor connection, voltage or ground, can destroy a pump prematurely.

 

OK captain hook I've checked the voltage at the plug and its 11.94 v and battery measures 12.2. Also for the grounds the thicker solid black measures .5 ohms that's where it seams to stabilize and the thinner black with white stripe measures 1.5 ohms stabilized