Thread: Mystery wire shorted 1990 RR

1990 3.9 Range Rover, Hotwire injection; Need help identifying a wire that has apparently shorted to earth and melted beyond recognition, it is hanging off the back of the alternator at the same connector as the alternator warning-lamp wire; i.e. two wires from the same spade connector. The car staggered and nearly cut out when going around a roundabout the other day, then missed a few beats a few km later- the charge lamp came on briefly during the second near-cut. On investigating, this wire has obviously shorted to earth and turned itself into a big fusible link. i can't identify where the other end should go, in fact I vaguely recall it may have been just hanging loose without going anywhere. If anyone with similar setup can have a look and tell me where it goes, that would be great. My other RR, although also 3.9 hotwire, is the serpy motor and the alternator wiring is similar but it doesn't have this wire.

The car has also started to run very poorly on petrol, okay on gas- I'm pretty sure this developed well after the wiring short, but not entirely certain as I run on gas nearly all the time. Behaves as though it were starving for fuel, also idles vary badly. Have not yet had a chance to investigate that. I'm kind of suspecting a broken fuel pump bracket dumping pressure inside the tank, as I've just done a high-country trip and noticed it after some heavy corrugations, but not entirely sure whether it may be related to the above.

Investigated the rough running today, fitted a fuel pressure gauge (I remembered I had one tucked away in the shed), 32psi, not leaking down when switched off, all okay there. Swapped the coolant temp sensor for a known good unit- no difference. Swapped out the ECU with a good spare- no difference. Swapped the AFM and discovered that I had stuffed up the refitting of the rubber tube between the LPG mixer and the AFM the other day, when I took off the air cleaner and AFM to investigate the shorted wire on the alternator. I had tucked the lower part of the rubber tube up inside the radius of the mixer intake- kind of like when a lady comes out of the loo with the back her skirt tucked into her undies:. Result was obviously a big opening for un-metered air (not to mention unfiltered) causing very lean mixture.
Nice to fix a problem without spending any money (although changing the temp sensor cost me a litre or so of coolant), but I'm pretty annoyed at myself for such a careless mistake. It added a little bit of stress to an otherwise very pleasant overnighter up to the high plains.
The shorted wire on the alternator seems to have had no ill effect- must have been an unused connection.