I'm putting in a fuel pressure sending unit and have some questions. Can I put it right after the water fuel separator? How do I wire the three wires from the guage? I have two terminals on the sender and three wires black, white, and green from the gauge.

I would not put the sender right after the filter, you want to read the pressure at the carb, in other words after the fuel pump.

The terminals on the gauge should be marked:

I =12v (to ign switch)
G= Ground (black)
S= sender

Good luck.

The normal fuel route is tank to filter/separator to the pump and last the carb. Putting the sender before or after the filter will read nothing. Mine is at the carb

thats what I thought about location. But 38kv, I only have two therminals on the sender? Which two wires go to the gauge? Thanks for your help.

Only one wire goes from the sender to the gauge.
If you have two terminals, I suppose one of them must be for a warning light .
I might be wrong here but I don't think there are any
fuel pressure senders who needs 12v to the sender.
If you post some close up pics of the sender and the gauge it would be much easier to help.

I'm doing some research, I'll be back in a couple of minutes.

I'll see what I can do about pics. But it's the one on the gaffrig website for fuel pressure of 0-15 psi.

thanks 38KV

One side of the sender goes to ground, the other to the gauge. The gauge reads resistance to ground.

Jersey Tom where would the third wire go?