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Fuel pump kill switch wiring
turboboy - September 29th, 2016 at 06:46 PM

Howdy all
I need a diagram for a good way to set up a fuel cut off (cut out) switch for a fuel pump if the motor stalls

helbus - September 29th, 2016 at 08:58 PM

You can use a Tachymetric relay. They only have a circuit while the coil is pulsing. So while cranking, to start, or while the engine is running it will provide power. They are used in LPG powered vehicles for fuel cuto off solenoids.

turboboy - September 29th, 2016 at 09:11 PM

Cheers I'll look in to that...:tu:

DasAuto77 - September 30th, 2016 at 09:31 AM

I just received a PEEL brand tachometric relay from jkampers, about $50. Meant to operate for a few seconds when ignition first turned on, and only with pulse from coil thereafter.

turboboy - October 2nd, 2016 at 03:17 AM


1303Steve - October 2nd, 2016 at 10:24 AM

from another post I made

"I had a tachometric relay from a EFI BMW on my sons 1303 but it didn't like the signal coming from the MSD, the tacho signal comes out of the MSD box and not directly from the coil -

So I've now fitted a double through relay.

87 not used
87A goes to the pump
85 goes to the oil pressure warning light wire
86 & 30 are joined and fed by the ignition switch

On this relay when its at rest with no ignition feed, no power comes out of the relay at 87 or 87A

Turn the ignition on and the relay gets earth from the oil pressure switch, no power comes out of 87A, it only come out of 87 which is not used.

When the oil pressure builds the warning light goes out and the relay has no earth so it goes back to rest state but power goes through the relay at pin 30 and on to 87A to power the pump, if there is no oil pressure the relay is earthed again which takes power away from 87A.

The BMW tachometric relay cost me about $80 or $90, the Hella double through relay was under $20

The things that are not ideal with this setup,
1. no fuel flow until oil pressure builds, not ideal if the carbs are dry for some reason.
2. pumps stays on until the pressure drops when the motor is cold as the oil is still gluggy


modnrod - October 2nd, 2016 at 07:49 PM

I've always used the set-up Steve just put up, except I just use a normal 4-pin relay, and a momentary push button to prime if needed (mostly not).
Works great for carbs.

11CAB - October 11th, 2016 at 06:46 PM

Just fitted the Peel Relay to my Beach Buggy. It operates the fuel pump for a few seconds when you turn the key on, then operates when getting a pulse from the coil. Easy to wire in and works great.
Bought it off ebay for about $40

turboboy - October 14th, 2016 at 03:04 PM

Thanks all, very helpful,Cheers