Oil pressure gauge

"my port engine oil gauge show

"my port engine oil gauge shows the max oil pressure. Another words the pointer is at the top of the gauge. the other one showes the pressure at around 50 psi. the oil level is fine and the engines run good, can anyone tell me where to look. John"

On my race car if the oil pres

On my race car if the oil pressure sender wire comes off the gauge will go full scale. You should be applying a variable resistance to one side of the gauge depending on the pressure applied to the sender. I believe the other side of the gauge is tied to 12v. It all really depends on how the gauge is built if the sender or wire becomes defective.

Switch gauges to prove it out. I always carry a mechanical gauge I can attach to a spare port on the Tee port where the sender is located.

"Let me say what joe said in a

"Let me say what joe said in a different way. Think the gauge gets 12 volts and the wire to the sender modulates resistance to ground based on pressure. Sometimes it works the other way. Ground the wire - needle pegs high, unplug the wire - needle pegs low.

Sounds like you have a bad sender. Unplug the single wire and route it to the sender on the other engine and see if the guage normalizes."

"I'd start by switching ga

"I'd start by switching gauge with the starboard side. if it is hard to remove the gauges, you can "move" the sender wires with jumpers.

If that doesn't do it, check wiring at the instrument panel to see if the Oil pressure circuit is grounded out. if that is fine, you have two more items to check.

first is the sender unit itself - the last is the harness interconnecting them. remove wire from sender's output terminal. Take an ohm meter and measure the resistance bewtween the sender's output terminal and ground. If it is less 200 ohms, with engine not running, replace sender. if ok, check the oil pressure sender's wire for continuity to ground."