I am trying to bring a 95 Disco back to life, it sat for I think about 18 months for reasons I dont know. I have had it running for short bursts but never for more than about 10 minutes. The issue I am working on now is I seem to be getting very erratic power to the fuel pump. I have jumped straight to the pump and it pumps just fine and I have had it come on through the relay and inertia switch, however when I have powered it up through the relay sometimes it comes on right when the key is turned or sometimes it will be several minutes later and I have not been able to find any common thing that seems to make it fire off.
Sounds like a bad fuel pump relay, they are pretty cheap, thats where I'd start.
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2nd owner of a '97 Disco with a ARB winch bumper, SD roof rack, Rover Racks ladder, Cooper S/T's and 220,000 miles on the clock and still a daily driver.
I replaced the relay already ( tried several to make sure) I dont understand when the relay is energized and sends power to the pump for 3 seconds or what ever the time period/ pressure level is, what is telling the relay that is is done
On the '95 I have no idea what tells the fuel pump relay to shut off after the 3-5 sec of the engine not starting.
The fuel pressure regulator is on the engine, but its purely vacuum operated.
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2nd owner of a '97 Disco with a ARB winch bumper, SD roof rack, Rover Racks ladder, Cooper S/T's and 220,000 miles on the clock and still a daily driver.
right, I dont think the fuel pressure reg shuts it off either. With the key on I have 12 at 85 and 86 but the relay is not activating its switch, if I leave the key on for awhile sometimes it will suddenly activate or if I manually activate the switch it will start to work (I took the housing off the relay) but it doesn't shut down. I am wondering if there is a sending unit in the pump that is invloved in this.
I doubt the sending unit on the fuel pump has anything to do with it, these trucks are not that smart.
On the non dizzy versions the crank sensor sends the signal to keep the fuel pump running.
Maybe the cam sensor?
I really have no idea.
It sounds like a bad relay but you replaced it and thats all I can think of.
Maybe a rusted grounding strap?
Best of luck man.
Please post when you get it sorted out.
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2nd owner of a '97 Disco with a ARB winch bumper, SD roof rack, Rover Racks ladder, Cooper S/T's and 220,000 miles on the clock and still a daily driver.
The fuel pump is only powered for the first few second after the key is turned on unless the engine is started. Once the engine is running, the ECU detects a signal from the distributor to tell it the engine is running and the fuel pump can run.
But, let's not forget that this is an 18 year-old truck and the fuel pump is well past its sell-by date if original.
I should have a new fuel pump in stock if you need one.
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P. T. Schram Rover Repair
Full-service independent Land Rover facility
I ain't got much a nothing at all, but I damned sure got it made. If you don't like the way I'm living, you just leave the silly Rover boy 'lone!
Yeah, my PM box is full. If you want help, need parts, are on the ledge and need to be talked back, e-mail me at PT@PTSchram.com or call me at 260-804-0458.
If you don't like my attitude, I really don't care, but I will help you fix your truck anyway.
Yes I love God Guns and my country - but that still doesn't make my fuel pump run for a few seconds when the key is turned on and the pressure guage says 0. Should the pump come on everytime the key is turned on or is the ECU telling it it needs to turn on when the pressure is low.
Yes I love God Guns and my country - but that still doesn't make my fuel pump run for a few seconds when the key is turned on and the pressure guage says 0. Should the pump come on everytime the key is turned on or is the ECU telling it it needs to turn on when the pressure is low.
It is independent of pressure. It runs when the key is turned on.
Disconnect the power to the pump. Rig your trusty test light (Snap-On, I hope) so you can see it from the operator's position. Connect to white/purple and ground. Turn key on. report back.
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P. T. Schram Rover Repair
Full-service independent Land Rover facility
I ain't got much a nothing at all, but I damned sure got it made. If you don't like the way I'm living, you just leave the silly Rover boy 'lone!
Yeah, my PM box is full. If you want help, need parts, are on the ledge and need to be talked back, e-mail me at PT@PTSchram.com or call me at 260-804-0458.
If you don't like my attitude, I really don't care, but I will help you fix your truck anyway.
OK - no power is going to the pump at the turn of the key. At the relay with the key on I have 12v at 85, 86, and 30. I have put new relays in and I have tried several different ones.
OK - no power is going to the pump at the turn of the key. At the relay with the key on I have 12v at 85, 86, and 30. I have put new relays in and I have tried several different ones.
Be careful with generic relays for the fuel pump circuit of a Lucas truck as the relays are unique and will kill the battery quickly.
Get out your trusty ETM, follow the circuit, jumper the circuit for the pump and tell me if you have power to the pump then.
If not, disconnect both oxygen sensors and try again.
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P. T. Schram Rover Repair
Full-service independent Land Rover facility
I ain't got much a nothing at all, but I damned sure got it made. If you don't like the way I'm living, you just leave the silly Rover boy 'lone!
Yeah, my PM box is full. If you want help, need parts, are on the ledge and need to be talked back, e-mail me at PT@PTSchram.com or call me at 260-804-0458.
If you don't like my attitude, I really don't care, but I will help you fix your truck anyway.
I can manually operate the relay and power the pump, I also disconnected the o2's and have the same result - key on does not send power to pump
also I can get the truck to start but it just surges (500 rpm - 1000 rpm) give it throttle it will run but rough then surge and die
A little more background info:
I have put in new plugs, plug wires, dist. cap, rotor and coil, cleaned MAF with MAF spray cleaner, checked fuel pressure at the rail (about 28psi when truck would run this morning). This morning I was able to stat the truck and let it idle for 7-8 minutes, it seemed to idle and rev quite smoothly, I shut it off and now it will start but not run idle surges up and down and engine runs quite rough.
When the key is turned to pos. 2 it energizs the "engine management" fuse - this sends 12v to pin #19 in the ECM which sends 12v to the fuel pump relay pin #85 which activates the switch in the relay that sends power to the pump for 3 seconds to prime it (Thank you "Rave"). I can trace the 12v all the way to pin #19 at the ECM plug but it is not doing anything once it gets inside the ECM, also my check engine light is not coming on when the key is turned to pos. 2, I fear my ECM is cooked - anyone have an idea on how I can test the ECM further or is there something else to be done that might revive this 18 year old piece of solid state technology. I do get a check engine light in varying degrees of brightness at different times when I have coaxed the engine to life.
So to finish this thread off - Problem solved by cleaning all the contact points and letting the ecu warm up by cycling through the on/off ignition cycle repeatedly, I think part of the problem was this truck has sat for a year or more and the ecu had condensation and a little corrsion going on inside of it and it needed some current going through it to wake it up. Truck runs pretty good right now I have only had it up to about 35 mph so far as I am trying to loosen things up gradually.
Thanks for the input and advise in helping to understand this thing and especially thanks for telling me about Rave
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95 Disco fuel pump - erratic
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