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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