4 replies to this topic

[morley]

Going to be wiring in my fuel pump soon, just wandering if anyones knows what size fuses i should fit inline with the ignition and starter feed.
It's for a metro turbo fuel pump.
cheers!

[Bob_R]

Going to be wiring in my fuel pump soon, just wandering if anyones knows what size fuses i should fit inline with the ignition and starter feed.
It's for a metro turbo fuel pump.
cheers!

Hi, the main point of a fuse is to protect the wire that feeds the appliance. So you should also calculate what size wire is needed. I would suggest you use 3mm wire and a 20 amp fuse. When I add electric fuel pumps to marine V8 chevvy engines I I always run them through a relay rather than loading up the ignition wiring.

[Cooperman]

You need to know the current required for the pump in watts. Divide that by 12 for the amps and add 50% for safety factor. So, if the pump draws 60 watts, divide by 12 volts = 5 amps, multiply by 1.5 = 7.5 amps. The next size fuse up from that is 8 amp (or maybe a 10 amp) so that's the one to use if you are just having a fuse for the pump on its own, which is best.

[mike.]

Don't just wire the pump straight to the fuse box.

You want to fit an inertia fuel cut off switch inline and bolt it to a solid surface of the car like the bulkhead - This way in the event of an accident the fuel supply is cut off. In a crash your fuel pump could be dislodged, fuel lines split/broken etc and electric fuel pumps can flow a large amount of fuel and will continue to pump until you switch the ignition off - Which you might not be able to do after a bad accident.

Inertia switches are fitted to pretty much any car with an electric fuel pump, you can pick them up for about a tenner off ebay - Mine came off a range rover apparently. They all work in a similar so it doesn't matter what car it comes off, you might be able to get one from a scappers for next to nothing and you can easily test them by simply giving them a knock to see if the button on the top pops up and breaks the circuit.

Alternatively you can fit an oil pressure switch which is what is mentioned in facet fuel pump instructions. That just means the pump is only switched on when your engine is running and has oil pressure - From a safety point of view though, an inertia switch is better as the supply is cut instantly.

[morley]

Yes i've got the wiring sorted, i just wanted to know the size of the fuses.
i'm going to be wiring the pump through a relay and fit an inertia switch and also the pump will switch off if the oil pressure is low too.

I'll find out how much power the pump draws and work it out. thanks!