clean/wash out a fuel tank, what's the best method?

[James]

My 75 wouldn't run using the front/aux tank. I pulled it today. It had a lot of trash in it including a small rock. The gas looked like weak Yohoo.
Any suggestions?

[Scodge]

I'd use soapy water to avoid the obvious explosion that will happen if you use gasoline. Use a dish soap like Dawn that's designed to disperse oil. Scrub out the inside as much as you can, rinse it out really well with clean water, and let it sit in the sun with the sender hole facing up, so the water can evaporate out.

You might consider buying one of the oversized aftermarket steel tanks that are out there. They hold more gas, and the sender units install from the top, not the side, so they won't leak.

There's also nothing quite like a fresh gas tank.

[James]

Thanks for the help. I was going to use water, but the dish soap makes a lot of sense.

[Viperwolf1]

Remove the small vent tube before you put water in the tank. That tube has two very small holes near the end that could rust shut.

If you want to increase the size read here: http://classicbroncos.com/forums/showthread.php?t=158610. I picked up 2.5 gallons of capacity.

[James]

Thanks for the tips.
I was able to clean out both tanks. I need to play with the front tank because there's a small leak where the filler tube from the body attaches to the filler tube of the tank. The rear tank doesn't seem to leak...yet.

[Viperwolf1]

Get a new sealing ring from the Ford dealer. I picked one up a few months ago and it was about $1 and in-stock.

[nhint351]

If you still have your tanks out of the vehicle, dawn may work OK but I done the same thing not long ago. I used a degreaser called purple stuff full strength,about a quart, and let it set for a full day then used a pressure washer to really cut thru the crud. Rinse several times after until water runs clear. Allow for evaporation for several days, outside if possible in full sun. Works great!!

[DirtDonk]

How do your gauges read? Now might also be a great time to re-calibrate your sending units if they need any help.

Paul

[James]

Okay, well, after cleaning out the tanks etc. The engine dies when I switch to the front tank. (I've gotten really good at removing and reinstalling the tank.) While it was out I installed some seats from a 97 toyota Cellica. They are lower than the seats I had and comfortable. I can now drive without being hunched over or looking at the top of the windshield.
Back to the tank...I guess it might be the pick up/sending unit even though I cleaned it while it was out. I guess it could also be the manual tank selector switch, or the fuel lines themselves.
Any ideas would be appreciated.

[nhint351]

Did it run on the front tank before you took it out to clean it?

Did you replace the fuel supply hose from the tank to the manual valve?

What condition was the sock on the tank pickup?

Not much else to check. Obviously the fuel line is OK from the valve to the fuel pump.

If you didnot before, replace the fuel line from the tank pickup to the valve.

If you have air pressure available, use low pressure to check the manual valve for a blockage.

Last of all inspect the tank pickup. Use low air pressure first or remove it for a visual check.

Do the easy stuff first. LOL

[Scodge]

I'm betting you didn't plumb the selector switch properly.

[James]

[James]

[Scodge]

What I was thinking was that you connected the fuel lines to the wrong ports on switch. If you reversed the ports for the rear tank and the main line to the carb, the switch would still work when set to that position, but the engine would die when you switched to the front tank.

[James]

When I removed the tank I never removed any lines from the switch.
Today using a small hand vacuum pump to test the flow from the front tank. There's fuel flowing from the sending unit, through the fuel line from the tank to the switch.
The switch seems to move an extra 20 degrees or so when it's switched to the front tank. I'm thinking that the switch is old and worn (no duh) and it may move too far and ends up restricting the flow. I "played" with the position of the switch and the engine ran for 20 min or so and never faltered. So I may just need to replace the switch.

[DirtDonk]

Sounds like it. At least you've got one possibility pretty narrowed down at least.
You could always just do it the "old fashioned" way, and instead of buying a new one, just get used to where it should stop, and do it that way from now on. Of course, when you let your wife or a friend drive it, and they mysteriously "run out of gas" because they didn't know your little trick. The situation could get a bit sticky. Not good I'm thinkin'!
When mine started leaking into the cab (a very common issue with older selectors) I went ahead and replaced it with an electric valve instead. Yeah, a bit more work, running a wire or two, and changing the hoses a bit, but it was well worth it to seal off the floor, not have any more fumes in the cab, make it easier to switch (using just the dash switch) front tank to tank, and giving me the opportunity to run return lines by paying for the more expensive switch.
Worked for me, so might be an option worth thinking about.

Paul

[DirtDonk]

Oh, and if things are still the same, a simple electric solenoid valve is actually quite a bit cheaper than a replacement brass ball valve. Then the fancy-schmancy multi-port return line solenoid valve is the most expensive.
Simple electric should be in the 20 to 30 range, brass manual should be in the 40 to 70 range, and the motor-driven electrics usually come in at about the $100 level. I think BC Broncos has the best deal on those right now. I've seen them anywhere from 70 to 140 bucks, so check around if you decide to got that route.

Paul