Adding a dash mounted electric fuel pressure gauge to my 7.4 MPI. Can I install the sender in the .25 -18 port on the fuel filter housing? Gen VI L29 1998-2000 Fuel Filter item number 3. Sorry cant post a pic of the diagram yet.

Is this the diagram you're looking for?

Yes it is. Thank you.

Yes, a sender can be added there, but your only going to see a vacuum, that's before the pump.

Would be better off connecting at the fuel rail.

That said, if you have trouble with pressure you will know it quickly with power issues. IMO a water pressure would be a btter gauge to install. With water pressure you can keep an eye on cooling system

Thank you AllDodge. Am I correct, there is also a port at the aft end of the fuel rail, just fwd of the distributor, that I can use for the sender?

Not that I'm aware of. There is a test port (Shrader valve and cap) at item 6 in link. Might be able to attach sensor where the Shrader valve is

https://www.mercruiserparts.com/bam/...31918/2705/130

It's been about 20 years ago but I remember connecting a sender there on a 1998 7.4 MPI which seemed to work well.

Looks like item 20, plug, on the linked mercruiser site might work for me. Will take a look tomorrow. Thanks for all your help guys.

Does anyone know what size shrader valve that is on the rail referenced in the OP? I ordered a "GM" female schrader valve fitting for it last year when wanting to add mechanical fuel pressure gauges at the end of the rail and it did not fit. Wobbled and/or was too large.

Thanks for any experience you can lend!
Keith

What did you get, shrader valves are the same?

If you got the OTC version JC0180-1280 is used to connect to fuel pressure gauge. There are two sets on threads on the female side. Its pushed further to engage the smaller shrader threads. The male side threads fits the hose going to gauge