Siphoning gas out of a bad tank

[MishMosh]

How to siphon gas from an unusable tank

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

xc_hide_links_from_guests_guests_error_hide_media

Why did I post this?

I have a dual tank system on my C30, but one of the tanks is currently not working. From time to time, when it was in use for a previous business, someone driving the truck would accidentally fill the wrong tank. My daily driver has the tank on the driver's side and the working tank is on the passenger side, so I made this dumb mistake myself, only to wind up stuck on a busy freeway, not even realizing what the problem was until after I'd spent far too much on a tow truck

The fuel gauge isn't working properly, either, and it shows empty long before I'm out of gas. Fixing both of these issues is currently low on my list for this restoration project, but it may get moved up after I ran out of gas again the other day. Fortunately, I was in a parking lot at the time and took a look through the toolbox to see what supplies I had available.

I found:
The hose I'd used previously to remove some gas from the tank (it's been sitting in there for probably a year!)
A bunch of empty oil containers, to be disposed of
A 1 gallon can of Camp Stove Fuel (White Gas), also meant for disposal
A small funnel

That'll work! So I poured the white gas into the oil containers, cleaned off the hose and funnel, siphoned the gas into the metal container (which gave a little octane boost!) and poured through the funnel into the other tank. I was able to get about 2.5 gallons, which easily got me to the nearest gas station.

Anyway, I was texting with a friend about this dilemma and they were skeptical I could pull it off. But I've been making beer and wine for about 20 years and transferring liquids between containers is at the center of that hobby! So I made a video to show off

But then I thought...it might actually be helpful to others if I described this method and post along with the video, so I made a quick MS Paint How To guide. I hope someone finds it useful!

Cheers!

 

[Albrigap]

This is why I put dual gauges where the big single gauge was.
This way I knew exactly what was in each tank with no surprises.

 

[BearKing]

This is why I put dual gauges where the big single gauge was.
This way I knew exactly what was in each tank with no surprises.

Can you get a picture to show us?

 

[sgrinavi]

This is why I put dual gauges where the big single gauge was.
This way I knew exactly what was in each tank with no surprises.

Doesn't the gauge show the level of the tank which is selected when working properly?

 

[75gmck25]

The dash switch is dual pole dual throw, and when working correctly it will switch between tanks and also switch to the sending unit for that tank. However, the wiring for the switch in some years is really crazy because GM wanted to make it easier to wire for either single or dual tanks.

To add to the confusion, on early trucks they wired the passenger side tank as main, and on later years the drivers side was main, so there are significant wiring differences from year to year. Early trucks also use a solenoid/switch for the fuel line that only has one terminal and it grounds through the frame, but in later years the solenoid has six terminals. Then add in the issues you get with two old fuel sending units in the tanks. Many folks don’t have the patience to troubleshoot, and the wiring never really gets fixed properly.

 

[AuroraGirl]

The dash switch is dual pole dual throw, and when working correctly it will switch between tanks and also switch to the sending unit for that tank. However, the wiring for the switch in some years is really crazy because GM wanted to make it easier to wire for either single or dual tanks.

To add to the confusion, on early trucks they wired the passenger side tank as main, and on later years the drivers side was main, so there are significant wiring differences from year to year. Early trucks also use a solenoid/switch for the fuel line that only has one terminal and it grounds through the frame, but in later years the solenoid has six terminals. Then add in the issues you get with two old fuel sending units in the tanks. Many folks don’t have the patience to troubleshoot, and the wiring never really gets fixed properly.

3 vs 6 port and rare unicorn manual valve vehicles. I found that if someone either did two valves to use 3 port senders or just one valve with 2 port senders you could have a manual turn valve if you source a new valve for a 67-72 f series, frequented with auxiliary tanks and ford repop parts produce their valves and plates which were on the floor

Ealry squares did similar but nothing can be found when I looked

Since I don’t use ethanol gas maybe some day I’ll try putting two manual valves and use the switch to change the gauge lol(2 valves because 6 lines need to be chosen between since I have return lines

 

[scrap--metal]

Glad you figured it out @MishMosh

I've never been able to get the hose to do what I want once it's in the tank. Twisting/looping it like shown in the OP's diagram has been basically impossible in my experience. It seems like the flap at the end of the fill neck always messes things up and I resort to sucking gas.

It works, but I suck at it and get left with a bad taste in my mouth. FYI, gas tastes much worse than trans fluid. I try to avoid siphoning.

 

[MishMosh]

This is why I put dual gauges where the big single gauge was.
This way I knew exactly what was in each tank with no surprises.

Then at least one of them might work properly!

The dash switch is dual pole dual throw, and when working correctly it will switch between tanks and also switch to the sending unit for that tank. However, the wiring for the switch in some years is really crazy because GM wanted to make it easier to wire for either single or dual tanks.

To add to the confusion, on early trucks they wired the passenger side tank as main, and on later years the drivers side was main, so there are significant wiring differences from year to year. Early trucks also use a solenoid/switch for the fuel line that only has one terminal and it grounds through the frame, but in later years the solenoid has six terminals. Then add in the issues you get with two old fuel sending units in the tanks. Many folks don’t have the patience to troubleshoot, and the wiring never really gets fixed properly.

This is actually super useful info. I just got a new job and with some extra money, my project can start again. I spent a morning underneath the C30 last week and took a good close look at the fuel system. Well...I took a look at all the pipes and wires coming out of it. Everything looks pretty clean. If the problem was like anything else on that truck, It's probably just some loose and frayed wires and I need to clean out all the dirt and dog hair and it will work perfectly. I'm hopeful the only problem is the switch itself. I'll try to take a look at that this coming week.

 

[MishMosh]

Glad you figured it out @MishMosh

I've never been able to get the hose to do what I want once it's in the tank. Twisting/looping it like shown in the OP's diagram has been basically impossible in my experience. It seems like the flap at the end of the fill neck always messes things up and I resort to sucking gas.

It works, but I suck at it and get left with a bad taste in my mouth. FYI, gas tastes much worse than trans fluid. I try to avoid siphoning.

I usually try with my mouth first (without getting the gas all the way through) and if I fail at that, I switch to this vaccuum and gravity system.

But you just reminded me about one of the most important tricks I forgot to post. DO NOT ROLL YOUR HOSES UP WHEN YOU STORE THEM! Hang them straight up and down and if you need a single curve because it's a long hose, make sure it sits with a long curved edge so it doesn't pinch. If the hose naturally wants to curl, it won't be very easy to control. If it's straight, it will work better, and you'll be able to feel your way a lot easier.

EDIT: Oh, lol, I guess I did post it, but I still emphasize it's importance!

 

[Albrigap]

Doesn't the gauge show the level of the tank which is selected when working properly?

Yes, but mine showed the fuel level on both tanks at the same time.
Left gauge showed left tank and right gauge showed the right tank.
I had to look down at the switch to determine which tank I was burning off of.
I will try and get a photo.

 

[Albrigap]

Here is the dual gauge I built.
It only required one additional wire from the tank switch for the second gauge.
It worked great and it showed what was in each tank, all the time, no matter what tank I was burning off.
The lettering came from model railroad.

You must be registered for see images attach