Draining tank of old gas?

[dlundblad]

My wife's grandma gave us her grandfather's old 1992. Owned it since 1996 and only put 40k miles on it. He loved this truck. She's in great shape overall and we'd like to get her going for cruising and home renovation runs. Unfortunately, it looks like she's been sitting for about 4 years with 3/4 of a tank of gas. I've been looking to bypass the fuel pump relay and either connect a hose onto the solid line behind the TB or where the fuel filter connects to the fuel line along the frame. (I'd replace the fuel filter while it's halfway apart too.) Another option is to simply siphon the old gas out of the tank the old fashion way. What say all ye? Thanks in advance and Happy Friday!

*I found this wiring schematic. (I realize this is for a 5.7 and up, but it looks the same relay wise.) Looks like I just need to connect pin A to pin E? I can't remember how many amps the fuel pump is fused at, but I would make certain the jumper was also fused to that.

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[caw_86]

I did it a terrible way, i dropped my tank and just dumped it in the drive way slowly over the course of the day and let it evaporate

 

[someotherguy]

Spend a few bucks and get a siphon hose that has the squeeze bulb on it. Use a couple zip-ties to attach something heavy to the end that you'll put in the tank - I used a caliper anchor pin from some F-word product I'd worked on previously; it was a bit smaller and thinner than a GMT400 door hinge pin. That will help it find its way to the bottom of the tank for best results. Just be careful bringing it back up past the flap in the filler neck.

This is how I drained any tanks at my salvage yard that didn't pass the smell test.

That old fuel isn't just potentially bad for your injectors, it's bad for your pump, too. That is, if it hasn't already funked it up.

Richard

 

[Road Trip]

That old fuel isn't just potentially bad for your injectors, it's bad for your pump, too. That is, if it hasn't already funked it up.

Valid observation. Obviously a judgement call depending upon just how funky the fuel is.

NOTE: I include the following for anyone who has a full tank of fresh fuel but need
to empty it in order to drop the tank to FOM. (Facilitate Other Maintenance)

*I found this wiring schematic. (I realize this is for a 5.7 and up, but it looks the same relay wise.) Looks like I just need to connect pin A to pin E? I can't remember how many amps the fuel pump is fused at, but I would make certain the jumper was also fused to that.

Correct!

The FSM always has you use a fused jumper, even though the circuit is protected
by a 20A fuse downstream of pin E. With fuel, better safe than sorry. (And always a good practice
to verify that an incorrect fuse didn't accidentally end up in this position in the fuse block.
Stranger things have happened.)

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Best of luck on the revival. Bet you a dollar that once you get this back on the road you
will feel seriously good vibes while you keep it busy earning it's keep.
:0)

 

[xXxPARAGONxXx]

You can supply battery voltage directly to the Fuel Pump Test Terminal (highlighted in yellow). Its very purpose is to test the fuel pump operation when battery voltage is supplied to it.

Look at the schematic. The Fuel Pump Test Terminal harness connects to Pin C of the Fuel Pump Relay. Pin C is continuous with Pin E when the relay is not energized, and Pin E is continuous with the power side of the Fuel Pump. The other terminal of the Fuel Pump is continuous with Ground. So, if you supply Battery Voltage to Pin C, fuel pump will operate, because the fuel pump will have power and ground.

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Note: This assumes the relay has good internal contacts at C and E. But again, we're not trying to troubleshoot a non-operative fuel pump. We're trying to operate a known working fuel pump using the least amount of work. That would be applying battery voltage (using a fused jumper wire) directly to the Fuel Pump Test Terminal.

 

[Erik the Awful]

Spend a few bucks and get a siphon hose that has the squeeze bulb on it.

https://www.harborfreight.com/fluid-siphon-pump-62609.html

I use a better quality version for racking my wine. Place your finger over the output end when releasing the bulb while you're trying to prime it.

 

[Drunkcanuk]

My wife's grandma gave us her grandfather's old 1992. Owned it since 1996 and only put 40k miles on it. He loved this truck. She's in great shape overall and we'd like to get her going for cruising and home renovation runs. Unfortunately, it looks like she's been sitting for about 4 years with 3/4 of a tank of gas. I've been looking to bypass the fuel pump relay and either connect a hose onto the solid line behind the TB or where the fuel filter connects to the fuel line along the frame. (I'd replace the fuel filter while it's halfway apart too.) Another option is to simply siphon the old gas out of the tank the old fashion way. What say all ye? Thanks in advance and Happy Friday!

*I found this wiring schematic. (I realize this is for a 5.7 and up, but it looks the same relay wise.) Looks like I just need to connect pin A to pin E? I can't remember how many amps the fuel pump is fused at, but I would make certain the jumper was also fused to that.

You must be registered for see images attach

On my 91,I disconnected at the fuel filter, slid a length of garden hose over the line into Jerry cans. Used a length of wire from the battery to the OBD port under the dash. There is a pin there for the fuel pump, you would have to look it up as it's been a while. Stabbed the wire in there and put came the fuel.
Right or wrong???? It worked.

 

[1998_K1500_Sub]

Yup, easy to use the fuel pump and a hose on the fuel line as earlier proposed.

If not too old, I pump the fuel into other vehicles’ fuel tanks directly to dilute / put it to use.

 

[dlundblad]

Spend a few bucks and get a siphon hose that has the squeeze bulb on it. Use a couple zip-ties to attach something heavy to the end that you'll put in the tank - I used a caliper anchor pin from some F-word product I'd worked on previously; it was a bit smaller and thinner than a GMT400 door hinge pin. That will help it find its way to the bottom of the tank for best results. Just be careful bringing it back up past the flap in the filler neck.

This is how I drained any tanks at my salvage yard that didn't pass the smell test.

That old fuel isn't just potentially bad for your injectors, it's bad for your pump, too. That is, if it hasn't already funked it up.

Richard

The bad fuel funking up the pump didn’t even cross my mind. Very valid observation indeed.

 

[1998_K1500_Sub]

The bad fuel funking up the pump didn’t even cross my mind. Very valid observation indeed.

I can’t deny that “it matters”, and I value Richard’s comments, but your pump has been soaking in that gasoline for a long, long time so…

Running a little bit, would it matter?

It’s not like it will be operating at much pressure, it’s just an open fuel line.

The pressure is low, so even if the fuel’s viscosity has increased a little bit, the pump’s still under a very light load.