draining the fuel tank

[stickybones]

Can't seem to find the answer in the archives...

If you have a hotwired fuel pump (I didn't do the hotwire job), how do you drain the tank from the fuel rail? Some threads say to jump the gray lead at the back of the alternator to +12v. But with my hotwire setup, I'm not using that gray lead anymore. Will powering that gray wire still work? Also heard to jump the brown wire on the alternator, but that doesn't seem right either.

Also, gnttype.org says to use a clear rubber hose to look for bubbles to know when the tank is just about empty. Is this the way to go or is there a better way to know when you have about 1/2 gallon left in the tank to not cavitate the pump?

Thanks for the help. Wanta run Sunoco 111 leaded next time at the track and it would be nice to empty the tank of that useless 93 octane stuff.

Mike

 

[azgn]

there is a black connector (and a green one) in the wiring harness under the alternator.....if you apply 12 v to the black connector, your fuel pump will run and you can drain the tank off the fuel rail.......you will know when fuel gets low...the pump will change sound......

 

[ShaunKris]

There is a wire on the fender for that too isn't there? Does anybody have a picture of it?

 

[SCOOBY DOO]

Fully explained in the video:

 

[BFlat]

Remove cap and Schrader valve from fuel rail. Attach a section of hose to the rail where the cap was. Put the other end of the hose into a gas can. Disconnect the wire going to the light under the hood. Connect it to the black wire azgn mentioned. Don’t jam it in there any further than it takes to make a connection. Pump will run and drain the tank.

 

[RUQWKNF]

Remove cap and Schrader valve from fuel rail. Attach a section of hose to the rail where the cap was. Put the other end of the hose into a gas can. Disconnect the wire going to the light under the hood. Connect it to the black wire azgn mentioned. Don’t jam it in there any further than it takes to make a connection. Pump will run and drain the tank.

That's the old school slick way to do it.
Just don't forget to reinstall the valve core back into the fuel rail -4an shrader valve fitting after you done draining. Otherwise ya gonna have a bad time and a big mess to clean up when you fire it up. I always made my own tank drain kit.
Take a piece of 8 or 10 ft pre-made stainless steel braided -4an fuel pressure gauge hose like Autometer sells and a 5 gallon race gas jug and put it either on a towel on top of the radiator support, or beside the car with a towel on the fender, if the hose is long enough. Then take a piece of wire with 1 alligator test clip on one end that gets connected to the back of the alternator's positive post underneath the black round cap and on the other end of the wire, the correct male spade terminal that clips to the factory's black connector's fuel pump test lead behind the alternator. You just need to protect your fender if you run the hose over it or the nose of the car with a nice soft towel. Also, you'll not only hear the pump change tone when going empty, but the hose will start spitting in the race gas jug.
Another slick way to do this, is to remotely mount a fuel pressure gauge over on to the inner fender, or power steering pump reservoir bracket. When you're ready to drain the tank, unhook the -4 an fuel hose that feeds your fuel pressure gauge, plop it into your race gas jug and hook up your hot wire kit. When you're done, unhook the power wire, let the hose drain a bit, then hook it back up to your gauge.

This is how I've done it with my last two cars and my current GN. On the Blue car, I went with a Jegs 180* black push lock to -4an female fitting, gray -4an push lock hose and a straight -4an female to pushlock fitting for the Autometer 2 1/16" mechanical fuel pressure gauge. And on Legend, I went with black 400 series push lock hose. Disconnect the hose from the fp guage, loop it around and into the fuel jug that sits on the radiator support and walla. Works perfectly.

Years ago, Buick vendors used to sell pre-made fuel tank drain kits. IIRC, ATR was first, CPP, then BGC, then Kenne-Bell.
But I could be mistaken. LOL
Hope this helps.

- Patrick