Hi all,

bought this tachometric relay (see photo) and I thought it was self explanatory to wire up, but it doesn't seem to work. Yes I have thought it could be faulty, but I thought I would ask here first.

I wired as follows, starting from the left in photo.

+12V Gas switch - I have this as 12V when key turned to accessories.

Pulse (Neg coil or H/Tension lead) - I have to negative of coil.

Black wire protruding with eyelet - I have to Earth

Gas Valves(s) - I have this wire going to the positive of my electric fuel pump.





Have I got it wired correctly as the pump runs as soon as I turn the ignition on, even if coil negative lead is disconnected.


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Next question sorry and this may make me sound silly, but on the dip stick you have a low and high mark. Do you still use these marks as normal if you have an extended/larger capacity sump attached. I vaguely recall reading that you didn't need the level as high due to the larger volume of oil.

Thanks for you help, Kev.

P.S. Turned the engine over tonight off the key, so not far off running

I would have wired the relay the same as you did....not much help really. Where did you get it?

Oil level with a deep sump is usually run at about 1/2 way as the full, as you said, less oil for windage issues yet still plenty available, that is unless your looking at higher than 7500rpm, then a big deep sump or run on full, always checking the level after engine has been run and all hoses full, so with a thermostat on your oil cooler, this can take

Your wiring sounds OK to me.

Tachometric relays normally supply power for a few seconds when they first get power... to get fuel pressure up on an EFI car. 6 seconds comes to mind, but after that should be no power coming through unless its seeing pulses.

On the oil level, I've always been told to keep the level JUST below the maximum line, regardless of sump size. That way bigger sump means more oil means cooler oil.

Oh actually... does it need to be earthed through the mounting hole at the top also ???

Some things do ya know... like VW wiper switches for example...

where do you get these relays from?? Been thinking about this safety set up on my fuel injected Ghia. Does the gas valve wire go directly to your pump or to a pump relay??

Check if the 'gas valve' is actually not an earth

Thanks all for your replies and I will check out the 6 second theory this morning and the possibility that the 'gas valve' could be an earth.

I just bought mine from and LPG fitter, only $45.

Cheers, Kev

Cheers for that info Steve. My injection system is MFI on the 2.4 porker engine. No fancy safety systems available back then. If you burst a fuel line our had a crash the electric fuel pump would just keep on going and dump your tank load. Not as high pressure as an EFI pump but it does has very high flow.
Well worth fitting something like this for added safety.

Sides (Dave) you were right, there was a preset timer. When I was turning the ignition on, I would hear the fuel pump straight away and not having the fuel tank in I turned the ignition off asap not wanting to run the pump dry. I just used a test light and sure enough, the power cuts out after only 2 seconds on this relay.

Thanks again, Kev.

Yeah, cool - glad you're sorted Kev !!!