I removed my oil pressure sending unit on my SBC and replaced the ACE hardware fittings from the sending unit to the block with anodized fittings. Now when I turn the key on the oil pressure guage pegs to the right - same with the engine running? Any ideas on what have I done wrong??

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Tom Corey
Melbourne, FL
87 Green T-Top GT 5Spd SBC ZZ3 V8

[This message has been edited by Tom Corey (edited 08-29-2005).]

Hey Tom,
Are you using the stock Fiero sender and guage? I had this same problem after my swap. With the key off the needle is all the way to the left. Turn the key to the on position and it jumps directly to the far right. With the engine running it still stays pegged to the right.
I could not figure out what was not working, but changing the sender did correct the problem.

quote Originally posted by t76racer: Hey Tom, Are you using the stock Fiero sender and guage? I had this same problem after my swap. With the key off the needle is all the way to the left. Turn the key to the on position and it jumps directly to the far right. With the engine running it still stays pegged to the right. I could not figure out what was not working, but changing the sender did correct the problem.

Thanks. Yes, I use the stock Fiero sender and guage. Its been in and running fine for years, until I changed the plumbing to anodized parts. Mayube the sender just went south at the same time.

Unplug the sensor and turn on the key. You could have a short.

This may be a dumb idea, but if the sender needs to be grounded (I don't remember) - aren't anodized parts insulated by the thin aluminum oxide layer that the colored layer is made of? If that's the case, it's a slight possibility that the sender is now insulated from engine ground, which may or may not matter.

Bad sender
Don

quote Originally posted by Blue Shift: This may be a dumb idea, but if the sender needs to be grounded (I don't remember) - aren't anodized parts insulated by the thin aluminum oxide layer that the colored layer is made of? If that's the case, it's a slight possibility that the sender is now insulated from engine ground, which may or may not matter.

You are correct--the oil pressure sending unit is grounded via its plumbing. If the gauge pegs to the right when powered up, either the rheostat in the sending unit has opened internally, or the circuit between the sending unit & the gauge is open (i.e. infinite resistance between the signal wire & ground).

Tom--a quick & easy test to verify that you didn't accidentally compromise the wiring while working... Oil pressure sending unit unplugged, ignition in RUN. The oil pressure gauge should still peg to the right. Now ground the tan wire in the connector... if the wiring between the connector & the gauge is working properly, the gauge should drop to zero. If this is how it goes, either the sending unit or its connection to ground via the anodized fittings you've added is suspect.

quote Originally posted by dguy: You are correct--the oil pressure sending unit is grounded via its plumbing. If the gauge pegs to the right when powered up, either the rheostat in the sending unit has opened internally, or the circuit between the sending unit & the gauge is open (i.e. infinite resistance between the signal wire & ground). Tom--a quick & easy test to verify that you didn't accidentally compromise the wiring while working... Oil pressure sending unit unplugged, ignition in RUN. The oil pressure gauge should still peg to the right. Now ground the tan wire in the connector... if the wiring between the connector & the gauge is working properly, the gauge should drop to zero. If this is how it goes, either the sending unit or its connection to ground via the anodized fittings you've added is suspect.

Thanks for the help! You were right, I lost the ground.

[This message has been edited by Tom Corey (edited 08-30-2005).]