Oil pressure gauge not responding

[Botta]

Hello all,

I own a 1991 22R Carb' manual rig

On my way back home from work I suddenly notice the oil pressure gauge going dead. I might have imagined it, but I think I saw the needle climbing to the high briefly just before it went dead.
After I got home I first checked if the sender unit was connected. It was.
I replaced the sender unit with a mechanical gauge and found that the oil pressure is within manufacturer spec'.
According to the manual the resistance of the gauge should be about 25ohms, I got 27.
As the manual instructs, I connected the wire going to the sender to battery ground through a 3W light and the gauge slowly rose to to the high zone as it should.
I have two sender units. They both have a resistance of about 40 ohms at idle which slowly decreases as the rev's go up.
I checked the voltage supply to the gauge. It receives 11.9V while the rest of the system is 12.5. It's a bit strange but doesn't explain the gauge reading zero.
I'm just about to give up.
Anyone experienced something similar? Any suggestions or tips will be greatly appreciated.

 

[Thefishguy77]

Have you checked your rig for grounds? Toyotas are famous for coordinating grounds. It's pretty cheep to just redo them. Took me under an hour to replace the main grounds. Usually when you have a voltage drop its a short or a ground. Good luck keep us posted


Sent from my iPhone using Tapatalk

 

[Botta]

Thought about it but the sender unit is grounded via the engine. I think that if there is a problem with the engine ground I would experience problems with the starter and ignition. Both are grounded via the engine. At least in theory.

What do you mean by "coordinating grounds"?
How did you "redo them"?

Thanks!

 

[robertd33]

you could try a temporary wire from the sender to the gauge to test.

 

[Oside5ka]

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