I wanna say Im not sure if this post fits here or not if it doesnt feel free to move it , I did the fuel pump 2 weeks ago ,thought it went again so I did it again,also replacing the filter, the pump relay and the pressure regulator I cannot get my pump to run unless I run 12volts(battery charger) to it from/through the pump relay harness ok heres whats been done and not a thing has changed 2 fuel pumps 2 filters fuel pump relay 1 fuel pressure regulator 1 ignition control mdule and 1 ecm all fuses are good and no broken wires anywhere what I did notice is no check engine light came on unless I was cranking it over nothing when you turn the key only comes on as you are turning it over also on the fuel pump relay harness the oranges wire should be Hot all the time (I think) but am only getting .36volts out of it I only got an hr into it today got busy playing mr mom WTF I tell her they just dont seem listen any help on this would be great

Since it isn't 3rd gen, I didn't think it was appropriate for the Tech/General Engine forum. Since it is a TBI vehicle, I'll let the TBI forum mods make the call.

its a 350 5.7 tbi motor I can see that its not an F body but c'mon it is a TBI and is a 91 Im sure someone on this forum can help

if your oil presure switch is bad it will keep the pump from running, i had a similiar problem a few years back, mine turned out to be the ecm, but i replaced all the same parts as you did, try replacing the oil presure switch/sensor

ok I didnt replace that because I can loop around it and it changed nothing and I tried a few ways changing nothing

Did you check for any codes? Does it even turn over? If not, do you have a VATS key with a chip and / or a security light?

Have you tried another relay? When I had the same type of problems i was able to use the A/C relay in it FP relay spot to diagnose the issue.

The SES/CEL light should turn on at key-on, engine-off (along with a quick blink). And the fuel pump should run for 2-seconds at key-on. It sounds like there is no power to the ECM. In f-body's there is a wire that runs along the passenger fender under the hood. This wire has a fuse inline with it. Usually near the battery.

This is the power feed to the ECM and I also think it feeds the fuel pump relay power. From time to time the fuse pops and the ECM loses power.

See if there is a similar wire in your vehicle. If not, then check the fusible links at the starter. Also check all of the fuses in the fuse box.

RBob.

no chip in the key ,no security either ,it turns over fine ,I have .36 volts to the orange wire on the relay harness


2 fuel pumps 2 filters
fuel pump relay
1 fuel pressure regulator
1 ignition control mdule
and 1 ecm these are all new parts not used

powderpainter, wanted to kick your thread as you responded/posted nearly the same time I did. This makes it easy to miss that post.

RBob.

thanks for that
,I have checked all the fuses and even replaced some just in case,but any fuse I have found is fine ,I cant find any fuse that runs like you say ,but do agree that the ecm isnt getting power due to the lack of the CEL/SES when I turn the key on ,

Im gonna do some looking around under the hood and dash will post later if I have any questions or figure it out
appreicate your time

Check the terminal block on the passenger side of the firewall. The ECM feed looks to be one of the two center terminals with a fusible link.

RBob.

ok I wanna just keep this up to date for those that have helped !

again on limited time I fixed the wire for the relay ,it was a fusable link holding it back not a fuse but a damn link ,but after getting that going I could not get it to start , the check engine light did not come on with the key in the on only the SEL light came on

I pulled the harness off the computer and every wire that was orange or red was getting 12+ volts at the harness that the ecm plugs into so I would have to say the new ECM is bad from autozone
not really sure how to check an ecm so I just took it back and switched it out for a new 1 but didnt get a chance to get back to it but will later today

so the problem looks to be a fusable link and an ECM

but not sure on that ,
from what I have read the ECM is bad if the CEL light dont come on when the key is turned to on am I wrong on that or could there be more to it

with the key on but not running you should get a check engine light, code 12

ok not sure what going on with the CEL it flutters off and on when you turn it over and then it starts but no CEL light with the key in the on position and its not on when running (thankfully)

but I put the new ECM in and it is running drove it to the gas station and drove home with no issues the real test wil be in the morning when its 16 degrees outside

but I think it was a fusable link in the begining and ended up being the ECM maybe I have burned it up somehow ? it acted kinda goofy the day before this all started so maybe it was the ecm and I blew the fusable link in testing stuff ,I dunno !

but for now its running and thats all that matters thanks for your time on it guys

ok it ran for a day LOL can the pick up coil stop the injectors from firing everything is the same as when it was running except I have no fuel coming form the injectors
(not looking forward to that if it is ) any way to test it before I pull it

and starts with gas poured in and still no CEL or SES light but it didnt show before this either ,I know those lights work you can see flashing only when the key is trying to start the truck , but dont come on or stay on either
so it went from running to not running over night ,I have everything but gas coming from the tbi but theres plenty a 1/2 inch away none squirting though