I need some fuel sending unit experts please
The tests I’ve done on the fuel system show the fuel gauge, IVR, sending unit and ground are all good. Wherein does the problem lie? Is there a separate ground on the rally dash that could be missing?
I really think you are missing how the gages work.
They do not ground. They should not be grounded.
The IVR gets a ground. That's it.
Lemme find the MTSC which should illustrate this.
I did not test the oil pressure unit other than temporary grounding to see if the gauge needle responded. (No movement)
So there's there's two possibilities, there's an open or high resistance.
Open could be the gage unit itself is burned out, the unit isn't getting power, or a break or misconnection or high resistance connection anywhere along the way to the sender, or even in the sender.
Is it possible for the IVR to be partially functional ( enough for temp gauge but not consistent enough for fuel and oil pressure-both of those aftermarket items)
Yes an IVR that has weakness or high resistance could restrict the current available.
Since everything is in the car, I think the easiest thing to do may be to get some 10 or 11 ohm resistors, and since they are cheap enough, grab some 22 and larger.
In the meantime see if there is any voltage at the oil pressure sender and then at the multi-connector on the bulkhead cavity for the oil pressure gage. Check that on the inside too if there is none. My guess is if there is none, then the gage may be burned out.
@RedFish posted that he'd seen that happen when the oil pressure sending wire would get accidently grounded when loose (because the plastic connector covers frequently get lost).
