ECMB problems! No fuel

[SoCalSlaughter]

At a loss at this point. Truck is 90' Suburban V2500 4X4 5.7 th400. A few days ago I was running errands, truck kept flashing engine light and would stumble then keep on driving fine. The night before i was driving to the hardware store and engine light came on, code 42. Went away after starting truck up again. Anyways, got home and went to back into my driveway and once I put the truck into reverse it shut off. It cranks but wont start. Turn key to ON and all lights come on but fuel pump does not prime. Took fuel filter off and cranked and no fuel. Replaced pump and same result. Followed wires from pump all the way up to the firewall where they meet into the fuse block. tested ignition module and its good. (Tested 4 times and checked with a spare) Truck cranks but no fuel. Checked fuel pump relay with 3 others, same result. Checked all wires on firewall to fuse block. Nothing it grounding out. And at one point when I was trying to turn to key to on, the ECMB fuse would blow. Did this about 4 times until it was able to hold and keep engine light on. Tested ECM from my 89 Suburban and same result. Dash lights come on, hear the fuel pump relay click and still no fuel. Checked voltage on fuel pump and getting about 8.45 volts with key on. Replaced pick up coil, same result. Im out of ideas....

[truckdude239]

8.46 volts is not enough at the pump you need atleast 12 volts. you need to check the ground side of the ciruit as well i've seen teh ground get rusty and not work.

[SoCalSlaughter]

Ive gone threw all the grounds, twice in fact and run 3 more grounds to make sure and still nothing. I took the 12v battery from my dirt bike, and ground the Negative to the frame and out the positive on the power feed to the fuel pump and it will run, but when I try to turn the truck over it wont power on.

[VetteVet]

copy/ paste from the internet.

If you are sure the pump is not running you need to check the grey wire for power and the blk for ground at the pump.The ground should be there all the time and power should be there for a few seconds when you first trn the key to run then there all the time in start. Or at the relay you can use a fused jumper wire across terminals 30 and 87 in the fuse box and see if it will run. Also I dont have a diagram in front of me but some older model Gm's had the fuel pump circuit wired through the oil pressure sender so you might want to look at that also.