I think i either have a bad gauge or sender since my starboard indicator shows 100 psi (max on gauge) when the ignition is on. The engine runs fine, so not sure where to start troublshooting. Thought about first buying a new sender & see if that fixes the problem. Question is, i do not know which sender i need, or where its located. I am assuming a 100psi sender since thats what my guage shows, so would this work? OIL PRES SENDER 100PSI 1-STA (IA15016 / TELIA15016). Would like to get it ordered so i can install it next weekend. Anyone know where they would be located on a 91 454?
Thanks.

if the gage goes full sweep then the sending signal wire has gone to ground... either fallen off and laying on the block or sending unit shorted internally.

Like was said, if it pegged and stays that way then its grounding out. The sender should be way low below about the # 7 spark plug.

So was my part # from boatfix.com the right one? I think i will order one just in case the wire is still attached & not causing the problem.

The sender brand has to match the guage brand. I don't what guages you have. My pantera had a VDO sender and gaffrig guage and it made the guage work backwards.

ok thanks. looks like i have auto-comp gauges. I will look around to see where i can buy senders for these.

that wasn't the sender. all gaffrig gages work backwards. its as close as they get to being accurate.

LOL.

In this case it was the sender. They were gaffrig precision instrument guages aka livorsi.