electric fuel pump supply suggestion sought - 312-8

[darren 49]

Can anyone tell me of a good point towards the front of the 312-8, to use as a power feed for an electric fuel pump?

The electric pump is mounted close to the old mechanical pump, so if there's somewhere closeby it'd help keep the loom tidier than running a feed from the key switch.

on my C101 K-series I could use the feed to the coil, but this being a Magnum, I don't have the traditional coil to use.

Thanks for any help and advice

[squonk 39,292]

I have a C-160 I'm thinking of putting a electric pump on. What I plan on doing is run a feed off of my switch to a power relay. Feed the other side of the relay off a fused feed right from the battery. Then feed the pump from the relay. A little bit of overkill put I have a pile of relays and I like feeding the pump in that manner so the relay handles the load and not the switch.

[JamesBe1 80]

Just use the power from the coil wire (the black one that runs from the switch to the coil). It isn't energized until you turn the key.

That's what I did. Very clean and simple.

[can whlvr 991]

its a magnum so no coil like a k series

[JamesBe1 80]

its a magnum so no coil like a k series

Take a look at your schematic. Find the wire that energizes the ignition system. That should work nicely. Also, you can pretty much use any wire coming from the switch that is energized in the run position.

[Kelly 1,028]

It's a magnum there is no power to the ign. it's a magneto set up like a briggs, it makes it;s own power.

I'd run it off the key switch with a fuse.

Or like Mike said he did that would be best with a relay in line.

[Save Old Iron 1,564]

A quick look thru the op manuals shows some years of the 300 series have either an "A" accessory or "R" charge terminal on the ignition switch. No access to 12 volts is present in the START position, but that can be overcome easily. When starting the tractor, turn the ignition switch to RUN before starting the tractor. A few seconds in the RUN position will energize the electrical pump, filling the fuel bowl on the carb enough to allow the engine to start. When the engine starts, and the ignition switch returns to the RUN position, the fuel pump will once again be energized and continue to feed the carb bowl.

If you MUST HAVE power to the fuel pump in the START position, we can discuss several other options involving relays and diodes.

[darren 49]

Thanks guys.

A bit of poking about with a multimeter showed the white magneto/ignition switch wire is +12v when in the Start and Run positions. I've circled it in red here;

I was a little apprehensive, using a non-direct source but it all seems to work okay after a quick test. If I implement this, I'll add a fuse but is it an acceptable solution? I just want to check that I'm not likely to damage the magneto with this setup.

[JamesBe1 80]

Excellent work Darren. It will work perfectly.

And yes, a fuse is a very good idea.

My tractor has the electric fuel pump wired right to the battery through a toggle switch on the front panel. It was a minor annoyance to turn it off and on whenever I used the tractor. Once I forgot to turn it off and it killed my battery. Using the key switch is the smartest way to go.