Mobile Fuel Pump Mechanic
Discussion
After final getting my immobilizer replaced and the starter motor turning over (thanks Dave), my fuel pump has decided to go on furlough. It's not the relays or the inertia so I would guess the pump contacts are the most likely culprit? I don't have any lifting gear and I don't suppose there is any other way to access the pump(?) so can anyone recommend a mobile mechanic who might be able to do the job in the Guildford area?
Cheers,
James
Cheers,
James
OK. Thanks for the pointers. Especially the low profile jack. Fly lead to the Volvo turns the pump over. Neighbours voltmeter tells me ~50mV at the proper wires (12.7v at the battery for calibration ). Those wires don’t look in great shape. Do they ever?
I’ve had a look behind the B pillar and everything is at least connected. Not sure which wires to test. New relays seem to click when ignition switched, as did the old ones TBH. Don’t think it can be the new immobiliser as the it’s wired to the starter motor, like the old one. Can it be ECU related? I could hook up a Rover Gauge... probably a good idea, eh?
Cheers
James
I’ve had a look behind the B pillar and everything is at least connected. Not sure which wires to test. New relays seem to click when ignition switched, as did the old ones TBH. Don’t think it can be the new immobiliser as the it’s wired to the starter motor, like the old one. Can it be ECU related? I could hook up a Rover Gauge... probably a good idea, eh?
Cheers
James
I probably should have checked RGauge first. When the relays click, is it the ECU first, then the pump if the ECU is working? RGauge thinks it’s connected but not getting any info, unlike a couple of years ago when it diagnosed the lambda. OBD for the win... does the immobiliser connect to the ECU?
Cheers
Cheers
My lack of electronics Knowledge is definitely a bit of a sticking point now. With the voltmeter I can see voltage and resistance between pins 85 and 86 on the ECU relay, hence the clock, but nothing between 30 and 87. So I would have expected no power to ECU but having read another thread, and hearing the stepper motor whirr, I would expect that there is power 🤔
Any idea what I’m doing wrong?
Cheers
Any idea what I’m doing wrong?
Cheers
Not sure what was happening yesterday but thanks to everyone for the tips. After checking fuse 2 and using the mutimeter correctly (to negative terminal) I determined that the ECU was in fact powered and the stepper motor indicated it was working. So I persevered with Rovergauge and bingo:
So now I can see that the fuel pump is manually activated in ECU (thanks Mark) but the voltmeter still says no volts between FP 86 and the negative terminal (easiest to find in the footwell than a good earth). So the FP relay is not clicking, instead there is something behind the dash that is clicking, plus the ECU relay.
Fuses 12 and 13 checked but seem to be OK. Voltmeter shows good 12.7V between FP relay pin 30 and neg terminal.
Any marks on my homework so far?
Cheers,
James
So now I can see that the fuel pump is manually activated in ECU (thanks Mark) but the voltmeter still says no volts between FP 86 and the negative terminal (easiest to find in the footwell than a good earth). So the FP relay is not clicking, instead there is something behind the dash that is clicking, plus the ECU relay.
Fuses 12 and 13 checked but seem to be OK. Voltmeter shows good 12.7V between FP relay pin 30 and neg terminal.
Any marks on my homework so far?
Cheers,
James
Sorry, yes, the main ECU relay is fully powered. I wasn’t measuring it properly before, ie. not to the negative terminal or a good earth. RGauge shows ECU is working normally. I’m not sure why it didn’t work before but disconnecting and reconnecting at the 3 pin junction seemed to sort it.
The immobiliser is not bypassed at the moment, it has been replaced with a new MT2(?), which is connected to ECU and starter, both of which are working.
The FP relay is definitely not clicking when I cycle the manual override.
I had a look at the lambda anyway. Two leads were around 200mV one was 0 ish. I think it was blue. Does that make sense? Pretty sure it was a lambda lead since I changed a probe before the last layup.
The original relays were connected when problem started. First thing I did was order two new relays of correct type from TVR parts. The ECU relay is clearly working, so i swapped them over as a sanity check. The ECU still worked, the FP did not. I think I’ll swap fuses 12 and 13 next, even though they look good to my untrained eye.
One other thing I should mention. When the problem started, the first couple of times, it just went away when I pulled out the footwell cabling to take a look. If I wanted to run a fly lead from the ignition circuit, to pin 86 on the relay, as a check, then how would I do that? Or should I just run it straight to the positive terminal? I guess lack of fuse could be an issue?
The FP relay is definitely not clicking when I cycle the manual override.
I had a look at the lambda anyway. Two leads were around 200mV one was 0 ish. I think it was blue. Does that make sense? Pretty sure it was a lambda lead since I changed a probe before the last layup.
The original relays were connected when problem started. First thing I did was order two new relays of correct type from TVR parts. The ECU relay is clearly working, so i swapped them over as a sanity check. The ECU still worked, the FP did not. I think I’ll swap fuses 12 and 13 next, even though they look good to my untrained eye.
One other thing I should mention. When the problem started, the first couple of times, it just went away when I pulled out the footwell cabling to take a look. If I wanted to run a fly lead from the ignition circuit, to pin 86 on the relay, as a check, then how would I do that? Or should I just run it straight to the positive terminal? I guess lack of fuse could be an issue?
OK. Just double checked. Still sub 1V at pin 85 & 86 and checked that still 12V+ at pin 30. Steve, I think from your diagram and your description that you mean fuse 12, so I changed this out for a new one just in case. Still no fuel pump. Out of curiosity I also removed the ignition switch relay but that just meant that the ignition systems never came on. So yes, I’m thinking the loop back thingumy. What next?
Just seen reread comments about ignition coil. I’ve not checked the voltage but the starter motor turns over, won’t this be the same supply?
Just seen reread comments about ignition coil. I’ve not checked the voltage but the starter motor turns over, won’t this be the same supply?
Edited by Coefficient on Wednesday 1st July 13:44
Edited by Coefficient on Wednesday 1st July 13:53
It does now feel we are getting somewhere. I located the loopback and the 3xgreen/white, 1xblack wires. All connections are 12V+ with the RGauge set to continuous fuel pump, although it sounds like that should not make any difference to those wires. Sadly the pump did not prime while I was buried in the footwell peeling off ancient insulation tape.
Good news is that the wire wiggling seems to have worked. The embarrassing news is that the last few tests the relay was in the wrong socket. The weird results made me go back to Steve's 2016 thread and I thought the picture looked a bit odd. I guess the long term solution is to properly re-wire from the loopback to the relay socket. Hopefully I can now get the car to a TVR specialist for this.
For more fun while the glove box is out though, I might try to replace the heater control valve motor. And if that works I may even try to get the blower fans working again....
Thanks to everyone for their guidance and encouragement!
For more fun while the glove box is out though, I might try to replace the heater control valve motor. And if that works I may even try to get the blower fans working again....
Thanks to everyone for their guidance and encouragement!
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