Way Outta Control
Join Date: Sep 1999
Location: The Palouse
Thanked 3 Times in 3 Posts
The TBI and MPI fuel pumps likely do look the same, but the problem is that they're different output pump pressures. The TBI would run about 13psi, while the MPI would run at about 43psi.
The ASD is engaged by the PCM. If that's working, it passes the voltage to the fuel pump relay. So, we need to know if there is any output voltage from the fuel pump relay. If the fuel pump relay is enabled then you'll have 12 volts on it's output connector pin.
Why isn't that at voltage at the fuel pump? There could be a problem with the wiring, or the fuel pump has lost it's ground. That's a pretty common problem with a Jeep.