I have a 2003 Isuzu NPR box truck, the fuel pump went out on it I replaced the fuel pump and fuel filter.
Now the truck start and runs, but has to be cranked along time before it starts and when I let off the key it seems to start up, but if I crank and crank it doen't start. Also when I bump the ignition it starts when I let off the key. It has 50 PSI fuel pressure when I energize the fuel pump. It is a 5.7 V8 Chevy motor vortec. Hope you can help.