Ok well my friend just called me and told me that his 99 cummins is running really shitty with no power. He said if he cracks a line on the injector it will smooth out. Do you think there is something in the pump broken and its making air in the fuel or something???

 

First of all - he needs a fuel pressure guage on the truck. These trucks have been around for a long time now and everyone KNOWS that a fuel pressure guage is an absolute MUST HAVE.

He needs to get his hands on an OBDII scanner and check to see if there are any codes set.

Also, you have to tell him to be very careful cracking injector lines, the pressure is well about 10 000 psi and can cause very serious injury of you get sprayed with that fuel.

He can try the APPS reset:

re-cal the APPS

turn key on (dont start)
slowly press accelerator to the floor
slowly let accelerator back up to idle position
turn key off
start truck and enjoy




If that doesnt work, he will likely need a new injector pump and probably a lift pump as well.

 

pressure at the connector tube is about 4500psi on a vp truck. also that way of resetting the apps doesnt change anything if its mechanically off. but if cracking the line clears it up (its probably evening out the miss) I'm going to guess its an injector issue. get the cleaned and pop tested and go from there.