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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Low87c10 on May 27, 2009, 10:31:43 am

Title: draining bad gas
Post by: Low87c10 on May 27, 2009, 10:31:43 am

I have an 87 C10 with fuel injection and about 5 gallons of bad gas in the tank. I tried siphoning it out the filler neck, but was unable to get the hose into the gas. (Tried several different hoses of varying diameters.) I really REALLY don't want to have to take off the bed and/or drop the tank unless it is absolutely necessary. Here are my questions:
1) If I disconnect the fuel line at the filter that is on the frame rail and turn the key on, will the fuel pump generate enough pressure to drain the tank? (I figure I can connect a hose to the line and run it to an empty gas can.)
2) If I do this, anyone care to give input...am I going to blow myself up in the process?


Any input or other ideas would be very much appreciated. Did I mention I really don't want to take the bed off?

Title: Re: draining bad gas
Post by: Captkaos on May 27, 2009, 10:46:43 am

I would go with option 1, but I would pull the line off the back of the filter instead  Your problem would be keeping the pump running as it only primes unless the engine is running.  Vile may know an easy way to bypass it to make it pump.

Title: Re: draining bad gas
Post by: eventhorizon66 on May 27, 2009, 12:45:22 pm

LOL.  Why not disconnect the filler hose where it meets the tank and drop your siphon hose there?  I've done this several times.

Title: Re: draining bad gas
Post by: VileZambonie on May 27, 2009, 12:49:56 pm

All you have to do is hook a jumper wire up to the pigtail hanging off of the fuel pump relay. This goes directly to the b+ side of the pump so hook it to battery b+ and the pump will energize. That will allow you to operate them pump. Just keep an eye on it. When it stops pumping shut it off otherwise you will burn up the pump and have to drop the tank anyway.

Title: Re: draining bad gas
Post by: Russ130 on May 27, 2009, 01:09:51 pm

I did what Vile says but remember as soon as you start hearing air getting sucked up you have to shut off the pump. Keep in mind these pumps not only pump the fuel but also use it for cooling the motor and lubrication.

Title: Re: draining bad gas
Post by: Captkaos on May 27, 2009, 01:47:46 pm

Thanks Vile, I forgot about the jumper on the firewall...

Title: Re: draining bad gas
Post by: Low87c10 on May 27, 2009, 04:14:08 pm

where can I find the pigtail and fuel relay you are talking about?

Title: Re: draining bad gas
Post by: VileZambonie on May 27, 2009, 04:28:29 pm

(http://i6.photobucket.com/albums/y228/Sabaka454/fuelpumprelay.gif)

(http://i6.photobucket.com/albums/y228/Sabaka454/fprly.gif)


Cavity C of the fuel pump relay is the jumper lead.

Title: Re: draining bad gas
Post by: Captkaos on May 27, 2009, 05:48:18 pm

it is right by the AC unit on the firewall at the top (as pictured)

Title: Re: draining bad gas
Post by: Low87c10 on May 27, 2009, 06:17:42 pm

AC...that's funny...this truck doesn't even have power steering...lol

Thanx all who helped.

Title: Re: draining bad gas
Post by: Low87c10 on May 28, 2009, 07:32:29 pm

Just to be sure I have this right...jumper from bat + to the c terminal will run the fuel pump...right?

Title: Re: draining bad gas
Post by: VileZambonie on May 28, 2009, 07:57:03 pm

yep

Title: Re: draining bad gas
Post by: Low87c10 on May 28, 2009, 11:14:10 pm

thanx again