Here's a good one!!!

[ozzie]

Ok, difficult one this - I have checked previous threads... with no avail.

When the car (450 '97 P) is cold all runs fine, however when it warms up to running temp (70 degrees) a few things start to happen.... when driving along at speed I notice the fog lamp button surround start to occasionally glow intermittently.

As the car gets hotter more happens...

i)the MIL light start to join in
ii) then the hazard warning surround
iii) then the fuel guage starts to go to empty and hestitate up and down

Then when getting hot (90 degrees) fog lamp surround, i), ii) & iii) are on and fuel guage on empty. Then the car starts to not run smoothly i.e. intermitent cutting of engine power.

I have done some research with the bible and looked at the wiring diagram which shows the lights, fuel pump, guage etc all on the same circuit.

Also, I have noticed that if I turn off the car (once warm) and then turn the ignition on again, the fuel pump struggles and the curtousy light dims as it tries to prime. This therefore explains the cutting of the engine power (lack of fuel/fuel pressure).

The problem has to be electrical (either earth or reduced potential difference), so I cleaned the earths (wheelarch, under radiator and transmission tunnel) .... no difference.

Do anyone have any suggestions? (I don't think it is my immobiliser, that seems to work fine!)

Thanks in advance, Ozzie.
p.s. headlights, dials, windows, etc. all OK!

[Incorrigible]

Would guess at something like the regulator, (as it's on the alternator it may be affected by engine temp)

Definately check the battery voltage at all temperatures

[ozzie]

I had the alternator reconditioned 3 months ago due to flucating headlight brightness. This fixed that problem.

Not sure it is the alternator, because there is no flucation of the high current components e.g. headlights, fans, etc. they all work fine! Voltage across battery also at 14.2v hot & cold..... Any other ideas?

[tvrbob]

Surely this is a classic 'earth' issue. One of the dash earths is loose and as things warm up the continuity of the earth may worsen. As earthing is lost power finds new earths by passing through other devices. You would see lights glow and in particular lights that are unpowered therefore not using their own earths.

[Incorrigible]

ozzie said:

Voltage across battery also at 14.2v hot & cold..... Any other ideas?

not at the moment, as you say there seems to be fluctuation on that circuit, if the battery voltage is constant, the circuit must have a problem with it. I've no idea how you could check that though