fixed] 00 Blazer 4.3L Low fuel pressure after repl

God bless you my brother's and sister's.
OK I know this has been asked before but when it keeps happening to me I have to make sure.
00 Blazer 4.3 L came in for an oil leak replaced oil pan gasket and timing cover gaskets. Customer said it ran fine now I have a no start. It cranked so I went to fuel, fuel pressure was 15 psi I sprayed carb.fluid and I got it to start so I get gaskets and fuel pump. Installed fuel pump and still get no pressure I jumped pins 30 & 87 I get power but still no pressure. I checked relay as seen on the Danner channel I get batt. voltage on pin 87 on pin 86 I get batt. voltage and on 85 I get ground. So I replace the pump again this time I get 30 to 40 psi sometimes pressure rises when switch is turned off. I can turn it on with the scanner so I think ECM is drivers are good. Have I missed anything that needs to be checked?
Thank you and I wish you all a Merry Christmas .

Diagram org.wire batt.voltage, gry wire prime wire, drk.green & wht.wire ECM control when cranking and primeand blk. Wire ground.

gilbert
what does the pressure go up to when turning it on with the scanner? have you checked for a voltage drop issue to the pump? on the power and ground side. does the pressure bleed off or is it just low? maybe a plugged fuel filter possibly. but I would definitely check for a voltage drop issue back at the pump. first. maybe try direct power and ground with a power probe or jumper wires from the battery and see if the results are different on the pressure

God bless you my brother's and sister's.

Hey Cheryl the pressure does go up slow and it will go to 30 to 40 sometimes when I turn the switch off it will get to 50 psi. While cranking it drops and will not start, Cheryl what is the allowed voltage drop? The pressure does hold when ignition is off it just won't start without help.
OK so you saying I can take a jumper pack and put direct power to the gray wire and them after that test jump the ground and see If the pressure changes.
Thank you Cheryl I like this test will do this first thing on Monday.

.5 volt is the most you want to see on a voltage drop. what does it drop to when cranking? im saying you could jump a power and a ground to the pump at the same time and check and see if the pressure goes up. but doing one a time would work to. backprobe the connector while cranking and see what the meter reads. maybe you just got a bad new pump?

God bless you my brothers and sisters.

Cheryl thank you very much for your help i went out this morning and did as you said. I did a voltage drop test on the power side and it was good. Then i did it on the ground side and get 8.34 v. so i put ground straight from the batt. and pressure jumped to 60 psi brought tears to my eyes. LOL I found a rats nest right by the wire harness so i just fixed the ground wire.