I have a new aftermarket oil pressure gage, (electric), that I'm planning on installing on my 3.4PR engine, along with new water temp, and volt gages.

I understand that the stock 2.8 oil pressure sending unit also activates the fuel pump in the event of a fuel pump relay failure, so...
would there be any other problems, other than not having the "emergency" fuel pump activation if I deleted the stock pressure sending unit and tube and installed my new sending unit at the 1/8NPT port next to the oil filter??

I don't want to clutter up the engine bay more with adding a "cobbled on" brass T fitting under the stock sending unit.

You'll be fine without the oil pressure back-up system. I've read in some threads that some people believe the ECM only provides power to the fuel pump through the relay when initially started, then the oil pressure system takes over once pressure has built up. This is not true. According to the '86 service manual (page 6E3-C2-4), When the key is first turned on without the engine running, the ECM will turn on the fuel pump relay for two seconds. If the engine isn't started within those two seconds, it shuts the fuel pump off and waits until the engine is started. As soon as the engine is cranked, the ECM turns the relay back on and runs the fuel pump as the primary source. The oil pressure switch is only a back-up system in case the relay or ECM aren't working properly.

I don't think there's anything to worry about. In a pinch, you could swap the A/C and fuel pump relay plugs. You'd get home, albeit with no A/C. Or you could carry an extra relay.

The 88 V-6 is the only year that the oil pressure sending unit feeds power to the fuel pump during "engine run". Earlier years you should be OK.

quote Originally posted by olejoedad: The 88 V-6 is the only year that the oil pressure sending unit feeds power to the fuel pump during "engine run". Earlier years you should be OK.

I don't want to be argumentative, but according to the '88 service manual (page 6E3-C2-6), this is not true. The circuit operation description and the wiring diagrams are identical in both the '86 and '88 manuals for the V6. The ECM provides constant power to the fuel pump relay while running, the oil pressure switch does also, once pressure has been attained, but it is a back up system according to both manuals. Is the '88 manual wrong? What's your source of information?

[This message has been edited by Bloozberry (edited 10-11-2009).]

Thanks for the reassurance guys!
I'm installing a length of braided hose from the 1/8NPT port, (yellow arrow) to a remote oil pressure sending unit that I'll install away from the headers and the cat and then route the wiring behind the firewall heatshield and up through the console to the dash.

I'm using an available NPT port next to the fan switch on the lower intake manifold for the new water temp. sending unit.(green arrow).

The old sending unit on the rear cyl. head and OEM temp. gage will remain in place for now. (I'll remove them later if all the new gages work well)

The new water temp sender *could* replace the OEM one and I might be able to use the original wires in the harness, but I don't like the proximity to the exhaust header.
I think the OEM wiring for the volt gage will work ok for the new aftermarket gage.

[This message has been edited by randye (edited 10-11-2009).]

Ooooh ahhhh... very nice.

quote Originally posted by Bloozberry: Ooooh ahhhh... very nice.

Old photos from my 3.4 rebuild last year....
It's still very clean, but not quite *that* clean
Just used the photos to illustrate what I'm trying to do.

I removed the electric sender and gauge on my 88 Formula about 4 years ago with no noticeable side effects.

Are you not using the stock 2.8L ECM? That "unused" port on the lower intake is for the cold start switch. You got something else going on like a 7730 swap?