Oil Pressure Gauge

[Eric Noir Dy]

Hm, where do I start…
I have a Prosport EVO electronic oil pressure gauge, for some reason when the brakes are applied, the oil pressure drops by nearly half.
The brakes don’t even have to be applied, just barely touching the pedal will cause the pressure to dip.
(i.e. @ cold idle 45psi, brake on ~25; @ hot idle 15-25psi, brake on ~5-7.)

– The factory oil pressure light never came on.
– Oil level is fine. Engine remains normal under heavy braking.
– I suspected charging system and gave the gauge it’s own power source and still have the pressure dip.
– Checked the gauge and it seems to be working fine. (grounded signal wire)
– Mechanical gauge remains stable.
– I’m moving towards the sending unit but I’ve never seen one do this before. Could it be that the sending unit isn’t grounded properly?

Topic

[Charles]

Grounds would be a good place to start. Check the ground strap between the body and engine.

[Eric Noir Dy]

Those are new, I checked those after grounding the sending unit to the body and checking for cont.

[Charles]

OK. Then check the ground and power connections near the battery.

[Donald]

the gauge may have an internal grounding issue. Check the voltage drop across the gauge terminals.

[Eric Noir Dy]

I’ll take your advices and just check every single ground. This can IS 47 years old so there’s a good chance.
Thanks guys.

[Delwyn Ching]

The gage is powered by 12 volts, where did you tap for the 12 volts?

[Author]

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