New fuel pump, now RPM drops and truck stalls...

[Ben Rover]

Hiyo!

Got a '98 Disco to replace the '97 (RIP old girl) and when I picked it up, the fuel gauge read empty although the tank was full. I ordered and installed a new fuel pump since the truck had 192,000km on it, I figured it could hurt. The installation went well, I was extra careful to vacuum the sand and debris from around the tank so nothing got in. Replacement was completed quickly, truck started, fuel gauge now works fine.

Then I drove off to a family dinner. Rock solid on the highway for a good 40km or so, got off the highway, come up to a red light, brake and truck dies...

Can't get it started for a few minutes then turning the key starts the truck, it revs to about 2k RPM and then dies, repeat ad nauseam. I was next to a gas station so I pulled up and filled the tank to the top. I was able to get to my destination painfully by constantly keeping my foot on the gas and running a few stop signs, when I got there, I let go and it died and coasted to a stop.

I checked the fuel lines and one seemed loose so I pushed it all the way in until it clicked and was secure. I figured that might have been the problem and drove home. Again a solid drive while on the highway but as soon as I got off and released the gas, truck dies...

Any ideas? I've searched this forum and others, similar cases but always a stepper motor issue or something similar. In this case, the truck was running perfectly before the pump replacement.

The fuel filter hasn't been replaced yet.

Any help is greatly appreciated!

[Ben Rover]

After doing some more non-Rover research, it sounds like the problem might be that the lines are sucking in air. The fittings from the fuel lines seem in really bad shape but they fit on same as on the old pump. Could jamming them in more solve the problem?

Basically it sounds like I may have connected them improperly...

[antichrist]

The pump pumps from the tank so it's probably unlikely the fuel lines are "sucking air" since there's no suction on them. If they were leaking more than likely you'd have fuel leaks.
How old is your fuel filter? You might consider replacing that to start.
Also don't overlook the obvious, that you have a defective pump.

[masism]

Any answer to this one? Was it the lines, or the pump?

[Ben Rover]

Pump seems to work fine but I won't have a replacement filter until this weekend. I'll post back results once it's replaced.

[greg409]

I also wonder what pump was installed, as I think some of the non-oem don't achieve the 37# minimum

Although you say it dies when you let off the throttle

On restart, is it rich? (fuel regulator?)
luck,greg

[Ben Rover]

As of this morning, new fuel filter fitted, now the pressure stays in the lines but the engine won't start.

Grrr....

[Ben Rover]

Refitted the old pump and no change whatsoever, no more pressure in the line.

Did some digging and traced the possible problem to the relay which I read might fail when the pump is replaced or toyed with and would cause the pump to start up but not continue to, well, pump.

I swapped out the relay module from my 97 to my 98, nothing.

I put the relay back and... nothing! No more pump sound at start up at all.

Then it got dark and I had to stop, going to check the fuses to see if maybe the swapping blew something.

Does it sound like I might be on the right track? I bought a new pump for nothing, although now I have a spare, I'd rather be more certain before I drop some coin on a new relay module.

[Ben Rover]

Dropping off the relay module today to have it checked by my brother, a damn fine electrician if ever there was one.

I'm going to pull out and completely redo the fuel pump wiring harness from the back to see if maybe the grotesque amount of corrosion in the connectors might be at fault.

All fuses report fine and working although not tested for power since I only had one set of hands last night