i have a 2001 gmc duramax LB7, and i have some form of fuel problem and i cant figure it out. why the cp3 pump is sending fuel back to the tank instead of to the injectors.

it has a new pump and regulator, pressure sensor, fuel lines, fuel filter, and i am all out of ideas on what to check.

i did a bottle test and everything was fine and injectors are fine.

this is what it is doing
about 2 weeks ago i came home and pulled in the driveway and it died (like it was out of fuel) but it had pently of fuel. i tried to restart it and it would crank but wouldn't restart.
so now it will start only when i use starting fulid and only stay running if i keep my foot on the pedal, as soon as i take my foot off the petal it die's. it will not start on its own and will not stay running

can anyone help
any idea's????????

thanks
matt

 

Sounds like the regulator may be bad. The return coming out of the CP3 is the fuel used to lubricate the pump internals. What was the return rates for the pump and injectors?