# Oil pressure gauge pegged



## 66goatframeoff (Nov 8, 2011)

I purchased a set of rally gauges from Ames everything is wired correctly as I had MH build the harness I have tried the 60psi sending unit and the 80psi sender both from Py my gauge pegs as soon as I start the eng not key on only running anyone run into this issue? Man gauge shows 30psi at idle and climbs accordingly with rpm. Would like to have a working gauge any help..


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## 67Twistytee (Feb 24, 2014)

Sounds like the rally gauge is not properly grounded. Did you use Teflon tape on the sender? Have you tried isolating the gauge from the sender? Turn the key on and pull the wire off the sender. Does it read high? Ground the wire and see if it returns to 0. If it does your gauge is ok and it's likely a problem with the sender.


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## BearGFR (Aug 25, 2008)

Sounds like what you may have is an oil pressure SWITCH (intended for use with an "idiot" light) and not an oil pressure sending unit. 
An easy way to tell is they look different. 
An oil pressure switch looks something like this:









An oil pressure sending unit looks something like this:









If you try to use a "switch" with a gauge, what you're describing is exactly what will happen. The guage will peg as soon as you turn on the ignition and stay there - even with the engine not running.

Bear


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