Thanks for your further thoughts.
- I haven't tried an independent earth but I have tested the earth in the plug and it's showing 0.0 ohms to one of the engine cover bolts. I did clean up the earthing point near the inertia switch last night.
- Thinking further on my suspicions of the relay I realise I've not ben thinking clearly. Any measurement I take with the relay in circuit is invalid as by the time I've turned the key and connected the multimeter the initial priming phase will be over.
- I've uncovered the hinge wiring from about 2" from the loom to 2" to where it goes in to the boot lid and it looks very good. I've also pulled the wires and none are broken
- Pumps are not expensive and this one sat for long periods of time (700 miles in 6 years prior to my ownership) so I've decided to change the pump.
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Wrt to your second question, the relay pack for my car (an early one don't forget, '96, chassis number less than 1900) has no discernible digital content whatsoever.
Roverlike: yes hinge wires, I was aware of this issue and have not checked yet. What connected with the engine management goes through this bit of the loom?
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Thoughts appreciated please - '96 mk1 1.8
The car conked out a couple of weekends ago and I had to be recovered home.
It was immediately apparent the problem was fuel pump related as I couldn't hear the pump when I turned the ignition on.
I won't lead you through my extensive diagnostic process however this is where I am now:
- With the ECU relay pack bypassed via a jumper cable in the 8 pin connector there is 12v at the fuel pump connector. Therefore the wiring and inertial switch would appear to be OK.
- With the relay pack connected there isn't 12v at the pump. This despite replacing the relay pack with a second hand one from MGFnTFBitz. (A 970 instead of the 710 originally fitted but I assume they are compatible).
- The fuel pump will not fire up either with the system rigged as per (1) or with 12v injected directly from a charger.
(3) above would suggest that pump is not working, and I'm about to get messy and pull it out of the tank and have a look. However (2) suggests that something else is at work too.
I am of course highly sceptical that two things have failed simultaneously though there is the possibility that one thing failing has caused another to.
One thing that I don't really understand is as follows: When you turn the ignition on (under normal circumstances) the pump whirrs for a second or two then stops. why is this? Is there a sensor somewhere that tells the ECU that the system is up to pressure and turns the pump off? Could there be pressure in the system explaining why with the relay pack in place there is no 12v?
Many thanks in anticipation of your help.
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