GM Truck Club Forum banner

61 - 70 of 70 Posts

·
Registered
Joined
·
13,592 Posts
Ok, you have me confused.

You tested the fuel pressure and you have 4 psi

You then changed a bunch of parts.

I asked you what the pressure was after you changed parts

And your answer was 10 to 13 psi when I started this thread

So I went back and re-read post #55 where you say "again I replaced" and you list a lot of parts.

I thought you changed all those parts a 2nd time.
Now, I'm guessing your just restating that these parts were changed.

So, I'm thinking you now only have 4 pounds.

Is the line clear? If you think the new pump and regulator are pushing out 10 to 13, a partly plugged line is the only answer.

If the line is clear, the new pump, or the new regulator is failing.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #62
Idk man I'm also getting confused I was thinking about just starting a new forum but yes I'm pretty sure your on the right track.

What should I do now?
Also which fuel lines matter most? I ask cuz there's 4 from the fuel pump if I replace any of them should I just replace the main one that goes through the fuel filter?

Sent from my LM-V405 using Tapatalk
 

·
Registered
Joined
·
2,887 Posts
Were you measuring your fuel pressure at the throttle body or at the filter?
 

·
Registered
Joined
·
31 Posts
Discussion Starter #65
Hey sorry guys been busy trying to get ready for farming dumb question is the pump supposed turn on every time you cycle the key? Or just once every 3 or 4 cycles?

Sent from my LM-V405 using Tapatalk
 

·
Registered
Joined
·
637 Posts
There is a delay, I'm not sure how long, maybe 5 seconds? turn on the key and when the pump stops turn it off and count to 5, if it doesn't turn back on count to six the next time, etc. This parameter isn't in the .bin AFAIK, it's programmed in the ECM itself. Some ECMs have a "hot start" parameter that will run the fuel pump for ~30 seconds but, I think those are mainly for southern climates.
 

·
Registered
Joined
·
7 Posts
Make sure the connector for the oil pressure sender isn't messed up or fell off. Swapped an engine once and took me a week before I realized it. It's hooked into the fuel pump relay and if I'm not mistaken won't let the ecm fire the injectors either. Right beside your distributor on the back of the engine. Supposed to be a safety feature if you lose oil pressure
 

·
Registered
Joined
·
2,887 Posts
There’s the misunderstanding about the oil pressure circuit. It’s not a preventive circuit. It’s a redundant permissive enable circuit. It will enable the fuel pump circuit when there’s adequate oil pressure. About 10psi will turn it on. It will not disable. It’s supposed to be a start enable if for some reason the fuel pump relay fails. A little extra crank time and it starts.
 
  • Like
Reactions: PlaywithTBI

·
Registered
Joined
·
7 Posts
Ah ok. I had read he had already replaced a number of parts including the ICM, couldn't think of anything else that would control the injector pulse
 

·
Registered
Joined
·
2,887 Posts
No worries. The distributor reluctor coil fires a magnetic pulse which gets converted to an electrical one by the ICM. That pulse is used for the injectors and the coil. The computer grounds both to initiate a large impulse spark and a shot of fuel. The ground for the computer is on the thermostat housing. That should be checked for good continuity.
 
  • Like
Reactions: PlaywithTBI
61 - 70 of 70 Posts
Top