I'm having a very specific problem with my 2003 Discovery. I rebuilt a 4.0 engine for it a few years ago and it has been extremely reliable and leak-free since then. Last week it wouldn't start for the first time and I couldn't hear the fuel pump prime, so I ordered another fuel pump and installed it. Then it wouldn't start one day (fuel pump wouldn't engage), but started the next several times in a row running errands and then again this morning wouldn't start. I've traced the wiring out and have discovered that ECM isn't sending the ground signal to relay to initiate the fuel pump relay- blue/purple wire from ECM C0635-18 to relay pin 86. The 30A fuse is fine and sending 12v to the positive side of the relay.
My question is- are there any other components or sensors that would prevent the ECM from sending the fuel pump relay a signal? Crank position or inertia switch? I'm hoping the ECM isn't bad as I understand that can't just be swapped with another D2 ecm. Any thoughts?

 

The crank senor can stop the signal from ECM.

I'd check spark. Since you know the fuel pump isn't running, if it doesn't have spark also...usually crank sensor. And being intermittent, this also suggest crank sensor. Also, you do know that that fuel pump runs only while cranking or running...and not on second position of ignition key for a few seconds...like most vehicles.

If you have spark, but no fuel pump running...then you could have an ECM issue or wiring harness issue (rubbed through or worn).

 

Yeah, CPS.

 

I have a crank sensor on the way but Discoveries do still prime for 2 seconds at key position 2. Mine is not pumping while cranking either, so I’m hoping it’s the CPS.

thanks for the help. I’ll know tomorrow if that’s the issue.

 

Did you check for spark?

 

Did the crank sensor fix this issue? I'm having the exact same problem.

 

I'm having a very specific problem with my 2002 Discovery. I rebuilt a 4.0 engine for it a few years ago and it has been extremely reliable and leak-free since then. Last week it wouldn't start for the first time and I couldn't hear the fuel pump prime, so I ordered another fuel pump and installed it. Still wouldn't start. Install new CPS and have spark still wont start. I've traced the wiring out and have discovered that ECM isn't sending the ground signal to relay to initiate the fuel pump relay. The 30A fuse is fine and sending 12v to the positive side of the relay. Any suggestions?

 

Could be a security lockout - red light flashing on the dash? Push the rest button on the firewall pass side. Lock/unlock truck three times. Finally, the ECU powers on the fuel pump for 20 seconds when you first turn the key to the run position, check and see if it commands relay on at that time. You can check the rave manual for a more detailed operation description.

 

Hi Extinct, Thanks for the reply. No security lockout. I checked the inertia switch and I also jumped it but not start... I don't seem to be getting the ground signal out of the ECM to initiate pump relay when the key goes on. I've read the Rave and identified the connectors in the circuit trying to figure out how and where to start to test circuit (light probe, multimeter...) electric trouble shooting is not my thing. Any advise appreciated. Thanks

 

Also have another question my ignition is really funky, key gets stuck wont turn without alot of fiddling. Do you think a bad ignition could cause the signal not to be sent to the ECM to release the ground signal to relay?