My oil pressure guage on one motor is spiked to the top when I turn on the key. Clymers gives a procedure to test it, but they don't say where to find it. Anybody know on an 89 7.4L merc??

Right next to where the oil filter would normally mount.

On my 1988 bravos there is a wire connection (butt connectors) inside the convoluted sleeving next to the distributor. I have two wires that run down the back right side of the engine from there. One is light blue and the other is off white (Ithink). One goes to the oil pressure switch the other the sender. I believe the blue wire is for the sender, but I could look it up for you to be sure if needed. Much more handy to do the testing at the connection then in no-mans land down around the back of the engine.

BT