fuel pressure sender
 

Would bad fuel pressure sender cause gauge in dash to be pegged ? dash gauge works OK, i checked that.

Typically a pegged guage will indicate a grounded sender wire. did you try unhooking the wire at the sender and seeing what it does??

Unhooked sender and gauge still peggs

With nothing connected to the sender terminal (at the gauge), would tell me your gauge is bad. If it still pegs with the sender disconnected the wire "might" still have a short to ground

How would i find the short?

Your first post says the gauge works good, which tells me you removed the sender wire on the gauge and it did not peg.
The wire which was on the pressure sender was removed the gauge still pegs.
This says it is the wire between the gauge and the sender.

Instead of finding the short in the wire, just replace the wire from the gauge to the sender

I assumed the gauge was worked because i unhooked the wire pigtail from the gauge that was pegged and switch it over to the other gauge on the engine that worked and it still pegged.

was working

I have a Livorsi gauge that behaves the same way. After you confirmed the gauge lead to the sender is good and sender ground wire is good, disconnect the sender's wires and check the resistance between your sender terminals. There should be resistance - i.e. not an open circuit. The resistance varies inversely with the pressure but I don't remember the specifics Livorsi provided me.

I switch regulator and sender from starboard over to port engine and gauge works fine now.

Do understand the sender, but not the regulator, what regulator was switched?

Next thing, I'm assuming the wire from the sender to the gauge was not used, because the gauge still pegged without the sender connected

I removed the regulator and sender from starboard motor and switch it to port the motor, I used original wire from port motor and gauge works like normal.