Full Version: Source for switched power ...
The fuel pump (early 911 Hardi internally regulated) on my '71 3.2 conversion with 40mm webers is in the front trunk with wiring running off the original wiring in the engine compartment. After having fuel pump problems at the track last weekend, I would like to simplify the wiring for the fuel pump and just run power from the fuse panel to the pump.
What would be a good source for switched power?
Is a relay needed for the fuel pump on a carbed engine?
Thanks
Eddie
It is always a good idea to run a relay to the pump. Since it doesn't draw that much amperage, you should be able to tap off of any switched fuse to run the relay, powering the pump directly from the battery.
I would also heighly recommend putting in a switch on the dash (ie another foglight switch) so you can turn the relay on and off as needed. It's always a good idea to turn the fuel pump off a couple of blocks away from your destination to let the fuel levels drop in the floatbowls to minimize fuel perculation after the engine is dhut off. The new fuels have a higher Reid Vapor Pressure, and really like to perculate!
I would also heighly recommend putting in a switch on the dash (ie another foglight switch) so you can turn the relay on and off as needed. It's always a good idea to turn the fuel pump off a couple of blocks away from your destination to let the fuel levels drop in the floatbowls to minimize fuel perculation after the engine is dhut off. The new fuels have a higher Reid Vapor Pressure, and really like to perculate!
Hardi pumps had problems when they were the OE installed pumps, and I wouldn't put one in a car today with all the quality alternatives on the market. The Cap'n
What pump was used on the original 914-6?
Avoid the ignition power as a source, you don't want any extra voltage drop to your spark coil.
since I often am forgetful, i would want to wire it such that it goes off with the key,a second switch can be added in series to independantly kill the pump, for the reason stated in the prior post, and for incase of fire (if you use the key to shut off the pump, you may lock the steering wheel, not good if your still moving!)
also consider a impact/roll over automatic kill switch, this will shut off the pump in case of roll over or impact, just incase you are unable to. this safety feature is mandated on modern cars.
since I often am forgetful, i would want to wire it such that it goes off with the key,a second switch can be added in series to independantly kill the pump, for the reason stated in the prior post, and for incase of fire (if you use the key to shut off the pump, you may lock the steering wheel, not good if your still moving!)
also consider a impact/roll over automatic kill switch, this will shut off the pump in case of roll over or impact, just incase you are unable to. this safety feature is mandated on modern cars.
You can use the stock wiring if you still have a relay board. You have to add a ground wire to the board to trip the stock relay, then the stock wiring has power. I'll write more details if you want.
QUOTE(Eddie914 @ Nov 4 2006, 03:52 AM) 
What pump was used on the original 914-6?
Bosch p/n 61 309 (911 608 107 00). The Cap'n
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