1996 vortech 5.7

the truck was running great one day shut down thought it was the fuel pump replaced it ran great for 5 minutes and then shut down have 45 psi of fuel when cranking if you pour gas down the throttle body it runs great till it runs out of fuel changed pressure reg have 12 volts at injectors but if you rverse the volt meter only have 4.3 volts on ground side put computer in a different veh and runs great pls help

45 psi. is not good enough to keep engine running. You need at least 65 psi. And when you probe the voltage (reversed leads), you say your getting 4.3 dc volts? or -4.3? Try going hot side of injector to a common ground instead of injector ground. Then go ground to common ground (you should get 0 volts).Also you dont need to crank engine to activate fuel pump. Use the fuel pump prime connector (little red wire at the underhood fuse/relay box).

45 psi. is not good enough to keep engine running. You need at least 65 psi. And when you probe the voltage (reversed leads), you say your getting 4.3 dc volts? or -4.3? Try going hot side of injector to a common ground instead of injector ground. Then go ground to common ground (you should get 0 volts).Also you dont need to crank engine to activate fuel pump. Use the fuel pump prime connector (little red wire at the underhood fuse/relay box).

what i meant was when the computer pulses ground to the injector it is as if your not getting good enough ground to make the injector work i tested another truck at the plug and got 12 volts on the hot side and _12 volts on the ground side so i know i have a good ground pulsing the injector and that car runs,go figure . but the highest i get on the fuel press has only been maybe 50 psi so maybe i have a fuel pump problem as well

Have you changed the fuel filter? A clogged filter will reduce pressure measured at the schrader.

Have you changed the fuel filter? A clogged filter will reduce pressure measured at the schrader.


did that also

Your voltage readings are correct as far as the other truck you tested. You should get 12 volts and -12 volts (when reversed) that means it has a good solid ground at the componet in question. My truck completly died in traffic when the fuel pump failed. But it was still working and putting out pressure. Just not enough , it doesn't take much of a drop in psi to leave you "dead in the water".