I purchased a Discovery, non-running, at auction, and just correctly replaced the fuel pump and filter, as well as a 100K mile service. Fuel pressure tests OK at the fuel rail, but vehicle does not start until three turns of the key to get the fuel system pressurized. I've timed the operation of the fuel pump, once the key is turned, to 20 seconds, then the pump noise stops. After the vehicle starts it runs fine. Is there a timer in the system or is this a defective fuel pump relay? Thank you for any assistance.
1997 Discovery fuel pump relay operation
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ptschram
Well-known member
Thanks. I searched the board and found out the 3 turns starting issue is not an unusual occurence. I suspect it's my fuel pump relay, due to the 20 second timeout, but can find no information on the proper function of the Discovery fuel pump relay. I would think that the relay should stay on the entire time the ignition circuit is energized. Can someone confirm that the pump noise should continue at all times during the starting process? Can all eight injectors have possibly gone bad from sitting parked for two years?ptschram said:
ptschram
Well-known member
OK, I'll help after all.
The pump only runs for a coupla seconds when you turn the key on to prime the fuel rail. The pump will not run again until the ECU receives a signal from the engine that the engine is running. It's a safety step to keep fuel from spraying out of a crashed vehicle that isn't running.
Also, on a '97, the fuel pump relay is part of the multi-function relay that also controls the fuel injection computer.
Yes, all eight injectors could have gone bad, or at least a few of them are leaking.
I'll bet that at least one of the threads you found when searching suggested checking the fuel pressure! There is a reason for this.
The pump only runs for a coupla seconds when you turn the key on to prime the fuel rail. The pump will not run again until the ECU receives a signal from the engine that the engine is running. It's a safety step to keep fuel from spraying out of a crashed vehicle that isn't running.
Also, on a '97, the fuel pump relay is part of the multi-function relay that also controls the fuel injection computer.
Yes, all eight injectors could have gone bad, or at least a few of them are leaking.
I'll bet that at least one of the threads you found when searching suggested checking the fuel pressure! There is a reason for this.
Thank you! The answer I was looking for. Upon initial start up the injection rail pressure was great. Injector(s) must have failed after running for a bit. Truck's done 10 miles since sitting after 2 years. I will do a leak down fuel injection pressure check, now that I know that the fuel pump relay is functioning correctly.
How do I check to make sure the fuel pump relay is functioning correctly and where can I find it?