Guage hassles. Pressure gauge , Oil guage !!!!!!!! whats wrong?

[TR]

My pressure guage goes straight to140. Can any one tell me why. New motor seems to run fine but I don't want to risk driving it if somethings wrong. Can it be wired up incorrectly?

Oil guage flat line, Is it the sender? How can I test it?

Fuel and tach seem ok.

[rnln]

If I remember right, someone posted a method which worked well for me. Pull the plug at the sender, touch it to the chasis, the gauge will peg top (or peg bottom, can't remember). Disconnect it from the chasis, the gauge will peg the other way. This indicate the wiring is well connected. That indicate the sender is the problem.
This post will help on replacing the sender: Question on replacing the oil pressure sender

[fintstone]

The sender is a variable resistor that changes resistance based on pressure...like a variable resistor (like turning a knob). Pegged (high) usually means you have an open (broken wire or bad connection) between the gauge and the sender....or the sender is open. You can test for this....If you disconnect and ground the lead that goes from the sender to the gauge, you should read zero. Open (disconnected should cause the gauge to peg. That tells you if the wiring is good to the gauge. No movement would usually mean a short to ground or a short across the sender.

For the oil level gauge, the sender is a variable resistor that changes resistance based on a float attached to an arm that rotates the variable resistor (like turning a knob). Pegged (high) usually means you have an open (broken wire or bad connection) between the gauge and the sender....or the sender is open or a bad ground on the other (ground) lead (brown) You can test for this....If you disconnect and ground the lead that goes from the tank to the gauge, you should read zero. Open (disconnected should cause the gauge to peg. That tells you if the wiring is good to the gauge. No movement would usually mean a short to ground or a short across the sender.

If both are bad (read open), there is a possibility that you have a bad connection at the 14-pin connector in the engine compartment (if I remember correctly, both run through that).
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74 Targa 3.0

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74 Targa 3.0

[TR]

i'll go out to the garage and check right now. thanks

[al lkosmal]

New motor? Tell us more about your car. What year? What engine? Typically the sender and gauge are matched. I.E. the sender will change its resistance, based on temp or pressure changes and the gauge will be calibrated to change its reading/display, based on that resistance change. (So a sender for a 1971 911 will probably not provide the correct resistance change to drive a 1980 911 Gauge properly, etc.) If you have installed a new/different sender(s) or gauges or senders....like, for example, a later engine installed in a older 911 ...you may run into this problem.