Ongoing Fuel pump issues

Im sure most of you have seen my 20ish posts about wtf is going on with my fuel pump... but just in case...

Fuel pump went out. replaced it, 2 weeks later, it stopped working. I thouht it was just a bad pump. replaced it. 4 weeks later, it stopped working again. When i turn it over, after about 5 min of cranking (yes 5 min, im sure my starter would be out by now if it wasnt brand new also...) i can hear the pump whine up and it starts. Deciding it wasnt the pump i repaced all the relays. Still nothing. Parked it in the garage until this week.

Since it took so long to start i was thinking it was a power issue. So i spliced in a switch to the power wire on the pump. I can hear it pumping. Or something, its turning on and making noise... but still no fuel or pressure at the rail. I disconnected the fuel line before and after the filter to see if it was pumping or not... its not. So now what? bad pump? Its new, probably less then 100 miles one. So im guessing that somewhere along the line, my Jeep is giving it to much power and its burning it up? Im really at a loss. Im thinking about adding a inline pump just outside the tank.

Speaking of. How much PSI does the fuel pumps in an 89 4L XJ pump out?

replaced the fuel pump again... and it started right up... ill give it maybe a week or 2 before it craps out again... what else should i be looking for while its running that would cause them to go out like that.

Ed

I cant find my FSM. Anyone able to tell me what voltage I should be getting at the pump?

You should have 12 volts at the pump, 0 volts after. If you have less voltage before the pump. check for unwanted resistances (broken wire, corrosion, bad connection, etc.). If you have more than 0 volts after the pump, say 4, then you have unwanted resistance on the ground side. Once again, check for bad ground connections, corrosion, broken wire. 12 volts before and 0 volts after is normal for the power/ground circuit. So it would be something else. Then you can test how much amperage the pump is drawing (if you have a DMM with an amp clamp). Pull out the fuel pump relay and make a jumper wire between the terminals for the power to the fuel pump. Put the amp clamp around the jumper wire and set the DMM to AC VOLTAGE, the number on the screen will be the amps being pulled. Normal would be about 2 to 8 amps. If it is drawing high amperage, check for blockages in both the supply and return fuel lines (clogged line, pinched line, bad fuel pressure regulator, etc.). If that even checks out, make sure the pump is being installed correctly. You want between 39-50 psi AT THE RAIL (roughly).