BEFORE YOU BUY A NEW PUMP.... check your voltage at the pump connector. I bought my D1 with a bad fuel pump. towed it home and spent a month messing with the pump. it would work, then quit, then work, then quit.. mostly if I drove it about 2 miles to the store, it wouldn't start. I would tow it home and it would start...

I pulled the dash apart looking for the mysterious spyder that I found out does not exist on North American trucks, thinking ti was a security thing.. Played with the relays on the pass side floor. and pulled apart the GEMS computer on the fender, and the Relays by the battery....

Finally the first thing I checked was the inertia switch on the firewall. seemed oK. I finally figured out the connector on the inertia switch had burned contacts and was causing a massive voltage drop which was dropping out the fuel pump. I cut the wire ends off and spliced the wires together, Have not had a problem for a year and a half since. I still have a brand new fuel pump sitting in a box on the shelf (just in case) (non AEL) i measured the voltage at the pump and got 9 volts, figured it had some sort of a load resistor on it to make the pump last longer at a lower voltage ( no manuals)

You should have 12 v at the pump. But you will probably need a second pair of hands to check it as it will drop off if there is no pressure on the fuel rail line on the motor after a few seconds. Turning the ignition switch off and back on will give you another few seconds of power (good for filling up the fuel rail)

I am really glad I didn't have to drop the tank to mess with the fuel pump!! Great idea to have an access plate in the floor.

 

Update:

After having a second person turn the key to the on position, I have 11.17 volts at the fuel pump. (Thanks again Antichrist for the pin-out diagram!)

I'm not surprised to see a reading that's a volt or so below 12. Here's my reasoning: My D1 hasn't been started since I sputtered home and parked it at the house. Since then I've taken the headliner out, repaired my leaking sunroof, and removed the rest of the rear interior trim panels to make it easier to fold the rear carpet and foam up and away from my fuel pump access hatch. I do a little here and a little there, so I've locked and unlocked the doors many times, as well as the few times I tried to start my Disco before I was sure that it wasn't going to start.

So the battery has been discharged some, and it hasn't been REcharged. The being the case, I'd assume that the 11.17 volts in seeing at the pump is to be expected. Right?

 

Sounds logical to me. Just make sure when you do restart it that you have about 14.1V across the battery terminals......eh.

 

Agreed. I definitely want to see just over 14V once I start it!

 

<12 seems reasonable given that you haven't charged the battery.
Is that the voltage between the 12v terminal at the pump and the earth at the pump, or between the pump and battery earth. I'd check it both ways.
Also, if you have a charger, hook it up and check at the pump while the battery is charging, but my guess is the supply is ok.

 

My supply voltage was around 7.5 volts and I found a bad connector. Once I bypassed it, voltage shot right up to battery voltage (12.5 volts)
A good idea to use the power and ground wires at the pump connection as that will tell if you have a bad ground connection too.

 

good catch that would have sucked if you redid the whole pump and it still didn't work because of a ground. you lucked out on that one.

 

Not necessarily, since you have no baseline. That's why it should be tested both at the pump and the battery, so can compare the voltage using the earth at the pump and the earth at the battery.

 

That voltage reading I got was from the pump connector only. It hadn't occurred to me to check ground at the battery, but now I'm too curious NOT to, so I'll check that this afternoon.

 

Alright, so I checked the voltage again using the negative battery terminal as the ground.

At the pump I'm seeing 11.05 volts. Not too bad. I expected to see a SLIGHT drop because of the resistance in the wiring travelling almost the entire length of my Disco. So I'm okay with a 100 mV drop. That tells me that my wiring is in good shape.