I have a 94 3500 that will not speed up while in gear till i am rolling a little. It speeds up fine in neutral but if you put it in gear it will not speed up or it does very slow. Acts really week. Changed the pump and injectors. Also put new ops and pmd on. Changed pedal pos sensor also. Only code i have is a 12. Any help would be good, Thanks.

 

Have you tried the lift pump test?

 

I installed a new pump to raise psi. The Psi is around 8 to 10 at idle. I think thats ok. Is that the test your talking about?

 

I think he is talking about opening the T-valve while truck is running to see if fuel comes out tube or motor dies but if you are getting PSI from LP it should be working.

 

I tryed that and it keeps running. I dont have any more ideas other than it seems like the fuel timing is off. But if some body knows how to check that please chime in