A member has asked me to help him get his fuel pump wiring installed and ready for engine installation. How do all of you conversion guys do yours?
He wants the fuel pump under the tank- no problem that I see, but would like the pump to turn off if the engine is not running. Stock, the ECU took care of it. Stock 6, I have not a clue. How did the factory take care of this issue? Is it even an issue with the 6? I assume the fuel pump output is going to be low pressure.
Thanks,
Tom

If it is a 6 conversion with EFI, the ECU will control when the pump turns on. Find the correct wire that controls the fuel pump relay.

If it is carbureted, the pump will run when the key is on. You could rig a counter and relay system connected to the coil. This could control the pump relay but is more difficult.

Put an inline pressure switch in the fuel line, to the fuel pump. When the switch loses pressure(motor dies) the circuit is completed and the pump quits.

Does a conversion need an initial pump running until the engine is running? Do conversions worry about loss of oil pressure to control fuel to carbs?
thanks,
Tom

On a real six, pumps run constantly when ignition switch is in the run position. . Webbers like 3 pound of fuel pressure, no more. . . A Holly regulator is most accurate and use a small gage on the spare outlet port. . some of the other regulators are not consistent in what they regulate at, especially the chrome one with the rotor dial. . Don't remember what it was but it wasn't very high quality . .
and yes, the pump needs to be able to run before your crank the engine. . that way it fills the float bowls if it has been sitting for a while. .

Yeah, 3 to 3.5 psi.

Depending on horsepower and build, make sure you have enough flow... basically 8 gallons per hour per 100 horsepower is the going rate needed.

RacerChris at Tangerine Racing has an affordable pump that would work for this. It's basically a Carter P60504 rotary.

Scroll to the bottom left.

http://www.tangerineracing.com/stainlessfuellines.htm

Thanks guys. I thought a /6 fuel pump ran whenever the key switch was on, I just wasn't sure. I expect that is what he will use also. Sometimes simple solutions are best.
Thanks again,
Tom

Since hearing about the Dodge Viper that burned to the ground at the Sebring race evidently with the fuel pump still running I'm looking at installing an oil pressure switch to the fuel pump circuit in my car. They are very much standard on many race cars. If the engine shuts off then the fuel pump shuts off.
I'd like to find a wiring diagram that will work for the 914 with carburetors. Anybody know of a good link to one?

Holley red fuel pump, Holley regulator set to 3.5 psi.

Done...

The problem with the Holleys and Mallory's is they need to be mounted vertically.

Some people want to mount the fuel pump under the tank and it needs to be horizontal.

I found this thread on a hot rod site. Looks like the oil switches sell for about $15-$20. You'd need one that would mount to a T fitting and be the right size thread.

Click to view attachment

Click to view attachment

You could always use an early VW/Audi fuel pump relay. They tie into the ignition, the tach or neg side of the coil. They cycle the pump on for about 2 seconds when the key is turned on and then turn on the pump as soon as it sees a ignition pulse and shuts off when the ignition pulse stops.
So if the engine shuts down for any reason, the pump shuts off.
It won't shut off the fuel pump if you lose oil pressure,wellat least not until the lose of oil pressure make the engine stop.

You do need to be careful with latter pump relays because they have a rev limiter build into and shut down the fuel pump to keep from over revving. Would cause great confusion when someone put a 4 cyl Audi relay in a 5 cyl Audi, engine would lose power over 4000 rpm or so.

Jim