The stock oil pressure gauge has never worked right since I've had the boat. The boat has good oil pressure I hooked up a mechanical gauge. I've bought new senders and different gauges and I have the same issue with all of them. I've even bench tested the senders and gauges to eliminate problems in the boat wiring. Here is what happens on the bench: If you hook power to the gauge and ground the gauge directly to a battery it pins the gauge......if you hold the sender wire to ground the gauge goes to 0. If you put the sender on the wire and ground it the gauge pins again. The sender measures .25ohms from end to end with no pressure. Every sender I have does. I have 3 gauges that do the same. What am I doing wrong or are all gauges bad?

The only thing that I can think of is that there is an 'oil pressure sender' and an 'oil alarm switch' both in the same proximity on the engine (lower port side). Two wires come out of the harness and lead to the same area. Could it be that the wires are connected to the wrong device? i.e. swapped?

I am using the gauge sender and not the alarm sender.......the larger of the two. I am baffled and this should be such a simple fix. Is it possible I have 3 bad gauges? When I turn the key on the guage should go up to zero right not pin past 80psi?

I had hours of trouble shooting the same problem. I found out that you have to match the sender to the guage not the engine. My engine manufacture called for one sender but it was different than what was required for the brand of guage. Also there is a different sender for what psi your guage will read.

I have Faria guages, and used the oil sender they call for.

The oil sender that my Volvo called for was not compatable with the Faria guage.

Does anyone have a stock oil pressure gauge that they know works off a late 80s formula that they want to sell? Thanks

I tried a sender off another formula with the same gauge and it still doesn't work.

One thing you should do is check the resistance of the wire from the gauge to the sender also double check the ground at the gauge and on the engine.

I agree, did you check the ground connections on the ground bar under the dash. I doubt all three gauges are bad, but I'm not sure the gauge would bury when you turn the key on without a good grd. Maybe try another forum, somebody knows.