Possible bad regulator? LQ4

[Brewtal66]

Hey everyone...

I've had an LQ4 swapped into my old Cadillac for about a year now. It's a bone stock LQ4. I have an Aeromotive pump supplying the fuel.

Now the thing runs beautifully...but I've noticed that after sitting all night, sometimes it cranks for a little while before firing up. Actually it tends to do this quite a bit.

It hasn't been an issue...it's just not an instant fire like my truck of wife's Yukon is. So I thought maybe something is up?

This morning I put a fuel gauge on the rail...zero pounds. I turned the key and the fuel pump runs for the few seconds and there's probably 60PSI or so at the rail. Soon as the pump cycles off, it goes down to zero. I did this several times. Starting it up and at idle, it has a solid 52-54PSI at the rails.

Is it possible I need some sort of check valve? Or is the regulator bad?

Thanks for your help!

[Sonar Chief]

Originally Posted by Brewtal66

Hey everyone...

I've had an LQ4 swapped into my old Cadillac for about a year now. It's a bone stock LQ4. I have an Aeromotive pump supplying the fuel.

Now the thing runs beautifully...but I've noticed that after sitting all night, sometimes it cranks for a little while before firing up. Actually it tends to do this quite a bit.

It hasn't been an issue...it's just not an instant fire like my truck of wife's Yukon is. So I thought maybe something is up?

This morning I put a fuel gauge on the rail...zero pounds. I turned the key and the fuel pump runs for the few seconds and there's probably 60PSI or so at the rail. Soon as the pump cycles off, it goes down to zero. I did this several times. Starting it up and at idle, it has a solid 52-54PSI at the rails.

Is it possible I need some sort of check valve? Or is the regulator bad?

Thanks for your help!

Tim ... happened on this thread, I have a 07 GMC truck that had exactly the same diagnostics and I had to replace the fuel pump assembly. The fuel pump houses the fuel pressure regulator which is letting fuel back into the tank instead of holding the pressure overnite. Everything is fine now!!!

Michael