Hello been some time since I have been on, part due to life just being crazy, and part due to computer having died. Anyway I have a 1996 Disco 1 with a 4.0. The problem I am having is the fuel pump is not kicking on and priming. Ran fine, then one day at bottom of dirveway it died, restarted after a couple cranks. After getting it home and then going to start it Sunday night it refused to start. The next day I was able to play with it realized the pump was not pushing any fuel forward. I replaced the pump with a new spare I had, replaced the filter, and still nothing. So tested for power to the pump and it is getting power, but still not kicking on. So I decided to test the pump in my project Disco(1995 with 3.9) and the pump kicked on fine. Have also checked connections at pump, and where it connects on LH rear near tank/frame all were good. Not sure what the problem might be and have rather run out of ideas. The relay(multi function)under hood makes a click when you turn the key to the on position, but that is bout it. Looked to see if there was maybe another relay for the pump but nupe just the big black one under hood against RH fender. Any help would be greatly appreciated as I am rather lost. Thank you and have a wonderful day

 

If you checked for power and that exists then check your grounds there is two grounds on that plug.

 

Thank you for the diagram, tested for power with light tester. I know not the best but was more a to see if it was getting power. Should I be running resistance tests as far as grounds go? Sorry may sound like a silly question but not very familiar with a volt/ohm meter.

 

Checked the two grounds on the wiring/plug going to the pump as it was a lil cold to pull the pump right now. Anyway first check they read at 5.7ohm on the 200ohm setting, then after I attempted to test the ground where it connects by the gas tank and frame which I couldn't get any reading, but that could be user error :P. Anyway after that retested the grounds and they read at 2.1ohm. So not sure if maybe dirty contacts on the under the car plugin, or if bad grounds, or whatnot. Will update this once I have been able to test the ground on the pump itself. *Note* Tests were done with one probe at wire that goes to pump from vehicle, other probe against the rod that the rear gate latches to.

Forgot to add this test was with only the ground cable connected to battery, and also am wondering could the relay possibly failing cause the ground to give those readings, or did I perhaps do the test wrong?

 

Your grounds should be .0 - .5 ohms at the 200 ohm setting your grounds are dirty. I usually keep a 10' ft wire with aligator clips on either end to run temporary connections for testing circuits. Just for now run a good ground to the plug on pins 2 & 3 at the fuel pump plug and check if it fires up when you turn the key to start it if it does trace the ground back and clean the connections.

 

Thank you so very much for the info, went out and cleaned out the ground contacts, both where it plugs into pump and where it plugs into the wires from up front. Tested pump and it kicked on, well the original pump from the rig. The new pump that worked in my project 95 disco 1 didn't want to work. So after much fighting with the seal to get the pump back in fired it up and well smoked like a chimney for a bit but that cleared up. Thank you once again. Now to see if I can't figure why other pump isn't working..well one of these days :P

 

Well it had been okay since last post. Granted I was only going out and starting it and let it run for a few min each day. Then yesterday had to use it to pull brothers truck to top of hill (deep snow, soaked ground) and at one point the fuel gauge went to E, and light came on. Shut it off, then started up again after redoing tow chain, and gauge was normal. Got done, and left it parked on top of hill just in case we got more snow. Went to start today and nada, cranks over but won't start again, and gauge is reading correctly. Checked connections(at pump, under car by tank) both were good and even unplugged and plugged back in, and no change. Now I am starting to wonder a couple things, could the multi function relay(under hood) be going bad, or is it possible that the pump is dying. Any help would be appreciated.

Thank You,
Bobby

 

Bobby,

Try the hammer trick, bang a rubber mallet or small sledge on the middle of the fuel tank from below while cranking. If the car runs fine after you do this, the sender is on its way out, put a new one in.

Otherwise my very rudimentary guess given your post above is perhaps some crud got stirred up from the bottom of the tank and either got into the sender or the in line fuel filter (I see above you changed it out already, so maybe not an issue there).

 

Thank you will give this a shot tomorrow, I did give the top of the pump a light tap with my hand, not sure why I thought that might help lol. Didn't change out the pump, well tried to with the one that was in my 95 3.9, but it didn't want to work so put the old one back in(worked in the 95, and the 96 4.0) and it ran fine cept for that one moment with the fuel gauge. Will update tomorrow with any progress, or lack of progress

 

So went out today to do the tap on the bottom of gas tank, but thought oh I will give it a try first. The pump kicked on, so I tried to start but no luck. Then I sort of timed the pump by the one, one thousand method and it ran till I reached 9. So not sure why it is staying running that long, also when turning the engine over it seems to sound about like it does if you pull the fuel pump fuse and crank it over to depressurize the system. Not sure what is going on, and plan to do some more tests on Monday, but if anyone has any ideas/thoughts I would welcome them. Thank you and have a great weekend