so, i got my rotary fuel pump in the mail today.
looking through the manual, they suggest to run the +12V from a oil-pressure switch. huh?

only thing i can think of is that this would shut off the pump if your oil-pressure drops below a certain threshold.

has anyone here actually done that ???
Andy

or it wont run until the engine has oil pressure.... (a few cranks)

Achtung....ya! It is a 3 pole switch that operates off oil pressure. Power is supplied to a NC / NO switch. In the NC it powers the pump on startup (power from start circuit). When oil pressure builds, the NO switch closes and continues to power the pump (power from ign circuit). In case of a problem (wreck) and the engine dies, it shuts the fuel pump off so you don't go up in flames by the pump constantly running.

As I remember, they cost about $30.00

Ya , I used to do that on the racecar till I got an inertial cut-off for the fuel pump. Makes sense..

Yep, that's the recommended installation. My car is wired like that. The pressure threshold is about 2 PSI, my oil light can come on before the pump quits. The starter motor can cover it while the oil is cold. So the oil pressure tap on the engine is now running the pump switch, oil light and the oil pressure gauge (911 style).

The theory is that if your car is seriously bent or inverted, the pump will not empty the tank making a bad situation worse. If the engine is not running, the fuel is not flowing. I believe that some of the possible circuits include activating the pump while cranking the starter motor, but my car doesn't have that. My car will fire with the fuel in the carb and the oil pressure will get the pump running long before the carb runs dry. Of course one time, shortly after hooking in the pressure switch, one of the pump wires came off while driving downhill, the car ran the carb dry before I figured it out. Stopped the car before I ran out of hill and put the wire back on. With hot oil, the starter would not create enough pressure to run the pump. Coasted up to 20 mph and spun the engine for pressure till thecarb was full, about 1.5 seconds. Since then I've noticed that I can jump the pressure switch, right next to the engine hood latch, with almost anything, paperclip, etc. though I have not needed to.

Let me know if you want more info...

Eric

PS. I think most people do not go to this much trouble...

hmmm, i'm using the stock fuel pump wiring which is tied into the ignition.
to shut off the pump, all i need to do is turn off the key.

the factory thought that was enough so i think i'll stick with what i have ...
Andy

PS: schanks for the info!

QUOTE (SirAndy @ May 6 2005, 05:16 PM)

hmmm, i'm using the stock fuel pump wiring which is tied into the ignition. to shut off the pump, all i need to do is turn off the key. the factory thought that was enough so i think i'll stick with what i have ... Andy PS: schanks for the info!

not sure how it is done on the factory /6 or the european 1.8, but stateside, the fuel pump will only run if the motor is running (ECU controlled on D-Jet*, AFM controlled on L-Jet)

*not counting prime circuit when key 1st turned on...