Fuel Pump Underhood Operating

[John Larkin]

I am planning to hook up a switch to pump the fuel out of my tank by connecting to the white wire/black plug coming from under the alternator, using it as a ground and getting power from the back of the alternator post. Since this post is always hot, do I need to turn the key on when pumping fuel or simply flip the switch and start the pump with the key off?

 

[MSDGN]

Just flip the switch...don't know if I'd hook up a switch though...just make sure you don't leave it on or the pump will continue to run...why not just take a piece of wire...put an alligator clip on one side and a male spade on the other...when ready to drain the gas...plug the male spade into the connector then attach alligator clip to alt terminal...easier and safer...JMO

 

[Steve Wood]

Yes, what Scott said. And, I am sure you did not mean it, but the fp test lead is not a ground. It is part of the hot circuit that provides voltage to the pump. When the pump is running, it has 12 volts on it and it has 12 volts on it for a couple of seconds when you turn the key on.

Connecting it to the back of the alternator sends 12 volts straight to the pump with the key on or off.

 

[John Larkin]

Duh! Yeah, I didn't mean it was a ground, just part of the circuit (you are too kind Steve!). Oh well, the mind fades with age.... As for the switch, I have one of those aircraft type red flip covers that turn off a switch when the cover is closed. You have to make a conscious effort to turn on the switch and I'll be watching for the bubbles to turn it off once draining is nearly complete. I just want a permanently mounted switchpoint so that it's one less thing I have to remember to hookup. Thanks for the replies!