I have a 1994 Jeep Grand Cherokee Laredo with a 4.0, I thought the fuel pump failed, I checked the fuses they are OK, I checked the fuel pump relay, there is 12volts there, but at the pump there are 5 wires. 2 wires for fuel level I think, 3 for fuel, black for ground, orange with black strip 10 gauge wire and one orange with black strip12 gauge wire. The small orange wire I get 12volts for about 3 seconds to charge the system when I crank the engine, the other orange wire I only get 4 to 5 volts constant and no fuel flow, I can apply 12volts to this orange wire from a different source and get the fuel pump to flow, BUT when I turn the key to start the engine, I get no power to the starter, I can put a momentary jumper switch across the starter relay and the jeep will start immediately and keep running. This works no alarm lights or other electrical problems but I would like to fix this problem correctly.

I have no wiring schematics; can anyone one tell me if there are any fusible links or the most possible broken wire area. Any help would be appreciated.

Thank you,
Henry
sierra19502@gmail.com

 

It sounds like your neutral start switch is the problem. Try moviing your transmission thru the gears and then start in park and neutral. If you have a manual transmission it is the clutch switch.

Starting it at the relay, you are bypassing the ignition switch and the NSS/clutch switch.

Check your relay socket. With ignition switch to start, you should have power at the socket for pin 86. You should have ground at the socket for pin 85 in park/neutral or clutch pedal pressed.

 

this could explain the problem we are having. the engine will crank, but it wont start. When it did start this morning it ran rough. That wouldn't explain the rough running though