fuel pump not playing
Discussion
There are a number of possible causes. You need to be methodical as phillpot suggests, don't just jump about wiggling things at random.
I have just replaced the pump on my car (an S3C), after it stopped working. To diagnose the problem properly, I suggest these steps:
1. As phillpot says, run a supply straight to the pump, with another direct earth. If the pump works, then your problem is in the car's wiring. If it doesn't work, it's the pump.
2. If the pump works at step 1, then try again using the direct supply, with the car's wired earth. If the pump still works, then the earth is ok. If it worked at 1 but not at 2, then the car's earth is duff.
3. If the pump still works with the direct supply, but not through the car's supply, then start testing the car supply. If you are switching on the ignition, and then running round to plug in a meter, you won't get a proper reading. The car has a fuel pump relay whose supply is controlled by an "engine running" signal from the ecu - if you turn on the ignition, the pump runs for 2 seconds. If the engine isn't running, the engine run relay cuts the supply - so by the time you get a meter on the supply, it seems dead. You need to watch the meter as you turn on the ignition - it should read 12v for a second or 2, then cut to zero.
4. If there is no supply with that test, then you need to check the fuel pump fuse. The fuel pump fuse is that clear 25A one beside the 4 silver relays in this pic: Those 4 silver relays control main/dip beam, front fog lights, engine cooling fan and the boot lock, so nothing to do with fuel supply.
5. If the fuse is ok, then you need to check the fuel pump relay, which is the yellow relay in this pic:
6. If all of those are ok, then check for corrosion in connectors in the wiring leading to the pump.
Really, take a step at a time - you might be lucky if you hit the problem by diving in at random, but working your way through it usually pays off.
What mine had done, just to complicate diagnosis, was:
fuel pump seized.
seized fuel pump causes fuse to blow,
fuel pump relay has corroded connectors and decides not to work any more after the fuse is replaced.
I have just replaced the pump on my car (an S3C), after it stopped working. To diagnose the problem properly, I suggest these steps:
1. As phillpot says, run a supply straight to the pump, with another direct earth. If the pump works, then your problem is in the car's wiring. If it doesn't work, it's the pump.
2. If the pump works at step 1, then try again using the direct supply, with the car's wired earth. If the pump still works, then the earth is ok. If it worked at 1 but not at 2, then the car's earth is duff.
3. If the pump still works with the direct supply, but not through the car's supply, then start testing the car supply. If you are switching on the ignition, and then running round to plug in a meter, you won't get a proper reading. The car has a fuel pump relay whose supply is controlled by an "engine running" signal from the ecu - if you turn on the ignition, the pump runs for 2 seconds. If the engine isn't running, the engine run relay cuts the supply - so by the time you get a meter on the supply, it seems dead. You need to watch the meter as you turn on the ignition - it should read 12v for a second or 2, then cut to zero.
4. If there is no supply with that test, then you need to check the fuel pump fuse. The fuel pump fuse is that clear 25A one beside the 4 silver relays in this pic: Those 4 silver relays control main/dip beam, front fog lights, engine cooling fan and the boot lock, so nothing to do with fuel supply.
5. If the fuse is ok, then you need to check the fuel pump relay, which is the yellow relay in this pic:
6. If all of those are ok, then check for corrosion in connectors in the wiring leading to the pump.
Really, take a step at a time - you might be lucky if you hit the problem by diving in at random, but working your way through it usually pays off.
What mine had done, just to complicate diagnosis, was:
fuel pump seized.
seized fuel pump causes fuse to blow,
fuel pump relay has corroded connectors and decides not to work any more after the fuse is replaced.
Edited by tvrgit on Tuesday 29th January 22:12
I have a similar problem on my S2. It just won't start after parking it in my garage overnight. There is no power at the pump and I have checked the two relays under the glove box. I can't hear a click from either when I turn on the ignition. Should the relay make a sound when ignition goes on? Also I swapped the two relays over as they seem to be the same rating. Still no joy. Could it be the ECU? There is no spark to the engine and no power at fuel pump. I am completely baffled. If it's the ECU are these still available and how much and where is my next question. Any help or advice appreciated. Thanks.
Tony. TCB.
Tony. TCB.
check everything that should work on the "ignition" circuit - ie not just fuel pump and spark. Do the ignition warning lights come on? Do the wipers work? If not, then the problem might be at the ignition switch - or the dreaded yellow connector that plugs the ignition switch into the loom under the steering wheel - a well known weak spot.
If the ignition circuit is definitely switching on, but there is nothing at the fuel pump relay and no spark, then again, as I said earlier, you need to be methodical - if you pull the 25A fuse out, is there a supply to one side with ignition on? If you pull the relay out, and "bridge" the supply terminals, does the pump work when you switch the ignition on? Don't leave it on - just long enough to see if bypassing the relay makes it work. You need to try to eliminate components (not by swapping a good one and a bad one - the circuit needs both to be working, I think).
If there's no spark either, though, and the yellow connector is ok, I would be thinking about the immobiliser.
If the ignition circuit is definitely switching on, but there is nothing at the fuel pump relay and no spark, then again, as I said earlier, you need to be methodical - if you pull the 25A fuse out, is there a supply to one side with ignition on? If you pull the relay out, and "bridge" the supply terminals, does the pump work when you switch the ignition on? Don't leave it on - just long enough to see if bypassing the relay makes it work. You need to try to eliminate components (not by swapping a good one and a bad one - the circuit needs both to be working, I think).
If there's no spark either, though, and the yellow connector is ok, I would be thinking about the immobiliser.
tvrgit said:
check everything that should work on the "ignition" circuit - ie not just fuel pump and spark. Do the ignition warning lights come on? Do the wipers work? If not, then the problem might be at the ignition switch - or the dreaded yellow connector that plugs the ignition switch into the loom under the steering wheel - a well known weak spot.
If the ignition circuit is definitely switching on, but there is nothing at the fuel pump relay and no spark, then again, as I said earlier, you need to be methodical - if you pull the 25A fuse out, is there a supply to one side with ignition on? If you pull the relay out, and "bridge" the supply terminals, does the pump work when you switch the ignition on? Don't leave it on - just long enough to see if bypassing the relay makes it work. You need to try to eliminate components (not by swapping a good one and a bad one - the circuit needs both to be working, I think).
If there's no spark either, though, and the yellow connector is ok, I would be thinking about the immobiliser.
As far as I can see four things do not work. The wipers and washers, engine fan and brake lights. Everything else seems to work. The pink engine relay and the yellow one has continuous power to one terminal on each, even with the ignition off. Is that normal? All fuses are intact and have been checked for good connection. Engine still refuses to fire and no spark at the engine. What now.If the ignition circuit is definitely switching on, but there is nothing at the fuel pump relay and no spark, then again, as I said earlier, you need to be methodical - if you pull the 25A fuse out, is there a supply to one side with ignition on? If you pull the relay out, and "bridge" the supply terminals, does the pump work when you switch the ignition on? Don't leave it on - just long enough to see if bypassing the relay makes it work. You need to try to eliminate components (not by swapping a good one and a bad one - the circuit needs both to be working, I think).
If there's no spark either, though, and the yellow connector is ok, I would be thinking about the immobiliser.
Tony. TCB.
ElvisWedgely said:
As far as I can see four things do not work. The wipers and washers, engine fan and brake lights. Everything else seems to work. The pink engine relay and the yellow one has continuous power to one terminal on each, even with the ignition off. Is that normal? All fuses are intact and have been checked for good connection. Engine still refuses to fire and no spark at the engine. What now.
Tony. TCB.
You have no ignition circuits at all, so it's probably not just the pump circuit.Tony. TCB.
There are 3 wires from the ignition switch that join the loom at a yellow connector under the steering cowl. One is a supply, one goes to ignition circuits, one goes to starter solenoid. Check that connector- it burns out eventually.
If that's ok, then check the ignition switch - is there a supply to the switch? Does the "IGN" terminal go live when you turn the key?
tvrgit said:
You have no ignition circuits at all, so it's probably not just the pump circuit.
There are 3 wires from the ignition switch that join the loom at a yellow connector under the steering cowl. One is a supply, one goes to ignition circuits, one goes to starter solenoid. Check that connector- it burns out eventually.
If that's ok, then check the ignition switch - is there a supply to the switch? Does the "IGN" terminal go live when you turn the key?
Thanks for the info. Yes the ignition light on the dash which is a picture of a yellow battery comes on when I turn the ignition key. There is a live supply to the ignition and I believe the AA man checked the the wires that exit from the ignition and they seem ok. There is slight burning of one connector which is a thick red wire but we checked either side of the connector and it seems fine. I am completely lost with this one and i thought I was fairly good at tracing wiring faults. There is a car electrician coming over tomorrow, let's see what he makes of it. Thanks again and if there is anything else you think might be worth trying before the electrician comes over please let me know.There are 3 wires from the ignition switch that join the loom at a yellow connector under the steering cowl. One is a supply, one goes to ignition circuits, one goes to starter solenoid. Check that connector- it burns out eventually.
If that's ok, then check the ignition switch - is there a supply to the switch? Does the "IGN" terminal go live when you turn the key?
- a lot of people jump to that conclusion for anything ignition-related, but in this case, I think that would be right.OK. Car electrician is here and after an hour and a half of sifting through the wires, my TVR burst into life. Job is not finished though. He has to pop back and get some things he needs and will be back to tidy up the wiring. Hopefully it will be up and running shortly. The cause was that stupid old Scorpion alarm system that was only partially disconnected. Me disconnecting the battery for charging activated it somehow. I am keeping my fingers crossed.
Tony. TCB.
Tony. TCB.
Thanks for all the help and advice gents. Problem now sorted by car electrician. It was an old disconnected alarm/immobiliser problem. Car up and running. Still there is a couple of electrical issues but its booked into the car electricians workshop for next week for 100% electrical check up to get all instrumentation working correctly.
Tony. TCB.
Tony. TCB.
glenrobbo said:
Glad Tony is sorted, but what about OP?
Any luck Andy? And why oh why is your Dad itching to pinch bits off your pride & joy?
It's not that unusual that you spend ages researching and typing to give advice, and the OP never returns to confirm or clarify, or even to say "thanks". You get used to it.Any luck Andy? And why oh why is your Dad itching to pinch bits off your pride & joy?
Hi guys sorry for not being back in touch.
Ordered new fuel pump but want to replace fuel pipes now from the petrol tank to the pump which is 15mm id. I'm thinking about a inline fuel filter between tank and pump, any ideas where to get re-inforced fuel pipe and maybe a small inline tap so I can change the filter without getting soaked in petrol.
I also want to replace the hard plastic pipe which goes from the pump to the fuel filter, any advice please.
Thanks for the above advise. I have checked the wiring and all is fine there but the pump is not pumping although it runs but nothing happens so fitting new pump this weekend, wish me luck!
Cheers Andy
Ordered new fuel pump but want to replace fuel pipes now from the petrol tank to the pump which is 15mm id. I'm thinking about a inline fuel filter between tank and pump, any ideas where to get re-inforced fuel pipe and maybe a small inline tap so I can change the filter without getting soaked in petrol.
I also want to replace the hard plastic pipe which goes from the pump to the fuel filter, any advice please.
Thanks for the above advise. I have checked the wiring and all is fine there but the pump is not pumping although it runs but nothing happens so fitting new pump this weekend, wish me luck!
Cheers Andy
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