No Fuel Pressure, 6.5 Volts at pump connector

I'm working on my buddies '87 XJ, the Jeep has been parked for a year or so and we are bringing it back to life. We first determined there is no fuel pressure at the rail and unlike my '88 XJ, we didn't hear the fuel pump come on when you turn the ignition on. I checked the voltage at the fuel pump connector nearest the pump and it measures 6.5 Volts with the ignition on. I measured the voltage on my XJ and it read 7.0 Volts with the ignition on. So we thought the pump was bad. We replaced the fuel pump and still no pump sound or fuel pressure.

we did hook the old pump up to the battery after it was removed to see if it was dead and it pumped fine...I'm thinking the connections where the wires go into the tank/pump assembly are messed up. Does the 6.5 Volts seem correct? Please let me know.

We didn't think to check the connection before we put it back in the tank. Bummer

I had a similar problem a while back on my 87 MJ. Check under the coolant bottle in the wireing harness. You'll see a bundle of spliced wires on the wire coming from the fuel pump relay. mine was all corroded, and was causing massive resistance to the fuel pump. I cut out the old bundle, soldered the wires properly and then smeared dielectric grease all over it before I heatshrinked the new connections. mine looked like there were just pressed together, but that could have been a PO mucking about. After that my pump got the proper voltage and has worked fine for about a month.
HTH

There is something wrong with both your readings, you should read 12v on your 87 to the pump. My guess it your meter is off.
Also take the reading with the pump connected. On the 88 jump the resisror on the driverside fender.
Replace the fuel pump relay.

Where exactly is the fuel pump relay...the schematics in my Haynes manual doesn't appear to show to resistor on the fender...I'm assuming the big ceramic one?...id the resistor in the fuel pump relay circuit?

The pump resistor is the only resistor on the driverside fender.

Here is a pix of the resistor and relays

Man, thanks for the help, I'll check it out. What manual did you get these pics from?..I have to have one of them....

Thanks, I got another voltmeter to verify the voltage tonight..

Some 87's have the resistor some don't. As far as I know none came with the resistor, but some had it added as a TSB, if the customer complained about pump noise.
I had low voltage at the pump in the wifes 87 about 12 years ago. It turned out to be a connector. I started following the wires from rear to front, checking the voltage at each connector. One odd thing I do remember the color of the plus wire changed, someplace in the middle of the harness and then changed back to the original color in the engine bay.
I'd test the ground wire as close as possible to the pump, for resistance. You could also probably check it with the pump running for standing voltage in the ground wire.
You might want to test the voltage of the pump wire in the engine bay, before you start checking the harness from rear to front. I got lucky and found the problem near the rear. It's no small job to remove everything on the inside to follow the harness, from the rear to the front. It would be a real bummer to do all that work and find the problem in the front.

i guess the thing that is bothering me...on my running well '88 XJ it measured 7.0 volts and the not working '87 had 6.5 volts at the same plug right near the filter....I was thinking the connectors right inside the fuel tank might be bad.....I'll go back over it all and see what I find...thanks

If the connector was bad you would be getting 12v not 6.5. If you can't hear the pump running when you first turn on the key, then most likely it is the fuel pump, sorry. The pump may have a piece of gunk stuck in it. Try shorting around the ballast resistor. That will put 12v to the pump. It won't hurt and may get the motor started again, But if it does, I would keep a real close eye on the pump from now on. Fuel pumps are notorious for going out on XJ's.

If you replaced the pump, make sure and check that you got the wires on the pump correctly. Some aftermarket pumps have the positive and the ground reversed in position. I have seen pumps hooked up backwards several times.

Just for some troubleshooting info that may help nail it down. You can get 12 volts on one strand of one wire, but your not gonna get enough amperage to run anything, but a very small light bulb.
Volts is kind of a quick check, lets you know you have some kind of continuity, but doesn't tell you if a connector is so corroded or loose, that it's not passing enough amperage.
Sometimes if you get low volts, it tells you there is resistance in the wiring. Resistance will often cause low amperage.
A bad analogy, but volts is like the water pressure in a hose and amperage is the actually the amount of water that comes out. You can get good pressure through a very small hole, but actually not much water.
6.7 volts at the pump connector (with it disconnected), is low even with a ballast resistor, which typically gives around 9 volts to the pump.
Check the voltage to the pump wire someplace up front. Look and see IF you have a ballast resistor.
You might want to jump a power wire directly to the pump, that will tell you it's likely the pump or the ground if it doesn't work.