Electric oil pressure gauge problem

[Gooch1962]

Picked up some gauges, volts and electric oil pressure. I got the lighting hooked up and the volt gauge, but I can not get the oil pressure gauge to work. It just pegs out, like a bad ground or something. It is an Autometer. I wired it up, just like what was on the back of it. The gauge just pegs out to max, over 100 psi when I either hook up the sending unit, which is (S) on the rear or it pegs out when I hook up a power source, which is (I) on the rear of the gauge. It doesn't matter if the ground wire is hooked up or not, still pegs out. Could it be a bad sending unit? Do sending units need to be positioned a certain way to work correctly? Any help or info is appreciated.

[Funkboy316]

no the sending unit doesnt have a specific way to be positioned however when you first cold start your car it will peg out. thats a normal reading on a cold start. however it shouldnt be pegged out once it warms up.

i dont think its a sender problem, it worked perfectly up until i took it out.

check out this thread: these are the pressures I was getting and you should get.http://www.newcougar.org/forums/showthread.php?t=91482&highlight=oil+pressure

[mond12345]

I have never seen anything over 80 psi in my car. On the coldest of morning start-ups it was at 80. Thats with Mobil 1 Fully Synthetic Oil.

[Gooch1962]

Okay I tried the gauge again today after driving home from work. I let the car idle and hooked the sender wire up, I then touched the ground wire and positive wire to the battery. The gauge still pegs out, over 100 and it is not a cold start situation. I'm thinking it has to be a ground issue, because touching or not the ground wire does not change the gauge from pegging out. Maybe the ground wires I spliced together for the gauges are not connected good. I'll check it out after I get some dinner. Any info is appreciated.

[Funkboy316]

what did you wire as a 12v power source also?

[Gooch1962]

Well When I first tried hooking the gauge up, to see if it worked I just tapped into the fuse panel for power and conneted the ground wire, also hooked up the sender wire to the gauge.
So today, since the gauge was out of the car. I hooked up the sender wire and used the + and - on the battery. I also tried another bolt for ground, but using the ground made no diff, the gauge would still peg.

[Funkboy316]

if you want to send it back to me i can test it out and we can go from there.

just let me know. i guess its possible it got damaged in shipping but there wouldve been some sort of noticable damge to the packaging. i still dont know what would cause the gauge to spike upon power connection, if there is no sender reading supplied. are you sure your wiring to the right terminals on the gauge?

[Gooch1962]

As far as I know I wired everything up correctly. No instructions. but markings on the back and what info I found on the net to make sure.
You have the GRD post in the middle of the gauge. The (S) post is for the sender wire. and the (I) post is for ignition or hot. That is correct, right?
I still think it may be a bad ground, haven't had time to check yet. I'll yet you know about the gauge, but I don't think it is the problem.

[Funkboy316]

that is correct for the wiring.