Is there a way to run fuel pump to empty gas tank?
11-06-2009, 09:25 AM
#1
Drifting
Thread Starter
Member Since: May 2006
Location: Wildwood Crest New Jersey
Posts: 1,794
Likes: 0
Received 1 Like
on
1 Post
Is there a way to run fuel pump to empty gas tank?
A friend has a 92 C4 ...has contaminated gasoline[water] in tank. To remove tank looks to be a huge job. Is there a trick to using a jumper wire to cause fuel pump to run constantly until the tank is empty? Some years ago i ran a pump in a 89 pontiac...i think[cant remember] i used a jumper wire from hot wire on lighter to a port on ALDL ?? Where the hell is the ALDL on a 92 C4? Or is there a trick using a car battery to do the job? I was gonna disconnect fuel line under car then run pump to empty tank. I do know not to run pump when tank is dry [burns out pump] Thanks Ed
can't get much simpler.
11-06-2009, 10:25 AM
#5
Melting Slicks
I bought a fuel pressure gauge with a purge line. If you put the key to the on position and press the purge line botton it would work.
At 40psi it whould be fun to say the least. LoL
At 40psi it whould be fun to say the least. LoL
11-06-2009, 10:30 AM
#6
Race Director
11-06-2009, 10:55 AM
#7
Drifting
I'd siphon the tank. Otherwise you run the pump dry and if your sock is deteriorated at all you're going to run all of that crap that'll accumulate towards the end through the pump and filter...no goodski.
11-06-2009, 11:02 AM
#8
Melting Slicks
11-06-2009, 11:18 AM
#9
Pro
Member Since: Apr 2008
Location: middle of Illinois
Posts: 542
Likes: 0
Received 0 Likes
on
0 Posts
You could disconnect the fuel line at the filter and short pin G to +12v under the dash. Turning the key on and off and draining it 2 seconds at a time takes a LONG time to drain just a couple gallons. Long enough you'll get sick of it and find a better way. 
But like the others have warned, this is also a good way to find out you need a new fuel pump. Which isn't a difficult or expensive job at all on these cars, and may be a good idea anyway if it's the original pump and has had who knows what contamination pumped through it.
But like the others have warned, this is also a good way to find out you need a new fuel pump. Which isn't a difficult or expensive job at all on these cars, and may be a good idea anyway if it's the original pump and has had who knows what contamination pumped through it.
11-06-2009, 11:47 AM
#11
When I changed my intake, I found that disconnecting the fuel rail will let all the fuel drain out if not plugged due to the gravitational pull. So I would say a real easy way is to get a wrench and open the fuel rail nut, and let it come out, if it gets slow you can probably jack the back up even more to help it. Or do the fuel filter deal.
11-06-2009, 12:19 PM
#12
Pro
Member Since: Apr 2008
Location: middle of Illinois
Posts: 542
Likes: 0
Received 0 Likes
on
0 Posts
11-06-2009, 12:50 PM
#13
Race Director
When I changed my intake, I found that disconnecting the fuel rail will let all the fuel drain out if not plugged due to the gravitational pull. So I would say a real easy way is to get a wrench and open the fuel rail nut, and let it come out, if it gets slow you can probably jack the back up even more to help it. Or do the fuel filter deal.
11-06-2009, 02:58 PM
#14
Pro
Member Since: Apr 2008
Location: middle of Illinois
Posts: 542
Likes: 0
Received 0 Likes
on
0 Posts
Even with my line disconnected at the filter, it only drained about a cup of gas until I turned on the pump. The fuel pump takes gas from near the bottom of the tank, but the supply line exits the top of the tank, so it would seem to me that gravity would not work to drain the tank without either turning the car upside down or creating a hole in the bottom of the tank. A siphon would be effective if you can defeat the anti-siphoning valve. Disconnecting at the filter and running the pump was the easiest way for me.
11-06-2009, 05:04 PM
#15
Race Director
As long as no air is in the line, fuel will flow from the tank to any point below the pickup in the tank (as long as there is no check valve). The line can run to the top of your house and back down and fuel will run out as long as the output is below the tank. Siphoning 101.
Last edited by 383vett; 11-06-2009 at 07:07 PM.
11-06-2009, 06:38 PM
#17
Le Mans Master
[QUOTE=reoch999;1572062833]yeah, check which pin, but one of them will run the pump. [QUOTE]
We all know how GM just loves to change things, but on my 86 it was pin 'G'. So who knows what pin was used on 92s.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
We all know how GM just loves to change things, but on my 86 it was pin 'G'. So who knows what pin was used on 92s.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
11-07-2009, 05:02 AM
#18
Safety Car
Member Since: Dec 2007
Location: Sandhills of North Carolina
Posts: 3,616
Likes: 0
Received 5 Likes
on
4 Posts
A 2.00 piece of 3/8 plastic tubing, a couple of 5 gal cans and gravity will get it right out. Why bother with the fuel pump? All the water is on the bottom anyway. Get that first if you can. Something rigid like a small piece of dowel or pipe to keep the hose stiff and will help get the hose to the bottom of the tank.
