Problem with Oil pressure gauge (Edit: Problem solved)

1992blazeredgs · Post by **1992blazeredgs** » October 25th, 2006, 6:34 pm

I finally got my sending unit in today, and when i went to turn on the car the gauge doesnt read any pressure. It goes from 0 to 10psi when the key is switched to on, and than doesnt read any higher than that when the car is actually running. Does anybody have any ideas of what to specifically check for before i am forced to tear it apart and check my wiring is correct.

Nate

max kl · Post by **max kl** » October 25th, 2006, 7:37 pm

i bet the gnd and s wires are switched. if wiring is good than gauge is crap.

1992blazeredgs · Post by **1992blazeredgs** » October 25th, 2006, 9:02 pm

Ok i switched the ground and sending wires around thinking i have them backwards, and the gauge went from being stuck at 10 psi from the moment the key is switched to on. To pegging at 100 psi and staying there until the car is turned off. Now i am even more confused and definatly think i need to redo my wiring.

Nate

PATDIESEL · Post by **PATDIESEL** » October 25th, 2006, 10:56 pm

Make sure you use the same size wire that the guage uses. Make sure your connections are soldered and shrink wrapped. To get a good solder, twist the copper threads together and let the soldering iron sit on the copper for a few seconds to heat the metal. The solder should melt from touching the copper and acutally sink down into the threads. If it doesn't sink the copper isn't hot enough. Do not leave the sjrink wrap close to the copper or it will shrink before you slide it over the joint. Wiring should be pretty straight forward. What do the directions read?

1992blazeredgs · Post by **1992blazeredgs** » October 25th, 2006, 11:05 pm

The directions were pretty straight forward. I soldered the wires and ran the proper 18 gauge wire. The wires are ran to the correct locations, so that only leaves me to think one thing. I grounded the gauge on a bolt on the back of the intake manifold, does anybody think that is not a good location? If so what is an example of somewhere better to ground the gauge. If that still does not fix the problem, autometer will be getting a phone call tomorrow.

Nate

max kl · Post by **max kl** » October 26th, 2006, 12:13 am

1992blazeredgs wrote:Ok i switched the ground and sending wires around thinking i have them backwards, and the gauge went from being stuck at 10 psi from the moment the key is switched to on. To pegging at 100 psi and staying there until the car is turned off. Now i am even more confused and definatly think i need to redo my wiring.

Nate

do you mean gauge is pegged when the engine is running or when key is on?
also how lond did you let it run ?
cold oil can run100 psi till it warms up and drops psi.

1992blazeredgs · Post by **1992blazeredgs** » October 26th, 2006, 12:50 am

when i switched the wires it pegged at 100psi with the key at on, engine not running. Initially when i first started the car up i drove it for about 5 min and it never left 10 psi. I am thinking there is either a problem with the grounds, or something wrong with the gauge or sending unit.

Nate

tehbrookzorz · Post by **tehbrookzorz** » October 26th, 2006, 3:01 pm

You can always run an extra ground from the battery negative terminal to the bolt on the back of your manifold.

I double grounded my engine in a simlar way. Even if it doesn't help, it doesn't hurt.

PATDIESEL · Post by **PATDIESEL** » October 27th, 2006, 12:32 am

Your ground is unnecessarily long. Take the little panel off the side of the dash (you'll see it with the door opened). There are a few places to ground under the panel. Try that first, then I'd get a volt meter and call Autometer to see what it should read when the car is on.
PS, the car should run about 60 PSI on start-up and go down to about 20 PSI at 800 RPM idle after it warms up or 15 minutes, which ever is shorter. When the RPMs are pegged mine runs about 80 PSI.

1992blazeredgs · Post by **1992blazeredgs** » October 29th, 2006, 1:29 pm

I double checked my wiring and everything was connected correctly. I shortened my grounds to the panel on the side of the dash so they are only about 1' foot long. I tested the wiring and i have 12 volts running to the gauge with the key switched on. So I am figuring the problem is with the gauge or the sending unit. Anybody have any other suggestions of what to check i would appreciate it.

Nate

tehbrookzorz · Post by **tehbrookzorz** » October 29th, 2006, 1:46 pm

Argh, I should have caught that your ground was too long. :p I guess I was too eager to tell you to double ground your engine, but I did that for other reasons anyway.

1992blazeredgs · Post by **1992blazeredgs** » October 29th, 2006, 2:14 pm

I was thinking just now and the problem has to be somewhere between the sending unit and the gauge. The wiring is correct, connections are good, so the sending unit must not be sending a signal. The directions say to use teflon sealing compound on pipe threads. So i put teflon tape on my sending unit before screwing it into the block. But the stock sensor i took out of the block had nothing on it. So could my problem be the teflon tape on the threads preventing the unit from getting a proper reading????

Nate

1992blazeredgs · Post by **1992blazeredgs** » October 29th, 2006, 6:40 pm

Problem solved, when i pulled the sending unit somehow a tiny bit of the teflon tape had gotton on the surface of the sending unit and had clogged the unit preventing it from sending a signal. Thanks to everybody that offered some help.

Nate