Tank cleaning advice???

[chrismorse]

My 74 has been out of service for almost 7 years. I have been reading up on cleaning the fuel system and anticipated some difficulty cleaning out the alcohol defiled gas crud I expected to find in the tank.
To my great relief, the tank actually looks quite clean, so, I am thinking I might not need to remove/replace the tank.
My plan is to pinch the fairly new, fuel line before the recently front relocated fuel pump, let it drain into several gas cans, pull and clean the screen filter out the bottom of the tank.
So, my question is, can you do a decent job cleaning an unused tank without pulling it??
It is finally up on a lift. What cleaning/flushing materials/techniques should I use??

The plan is to replace the tunnel supply and return lines with some of Len's fine parts as well as installing a cleanable "pre-filter" I know this is a bit redundant with the stock in tank screen filter, but it seems like cheap insurance - significantly easier to inspect/clean than the in tank unit.

All of the rear lines have been replaced, except a section of the original return line, which is on the list.

Thanks,
chris

[3rd_gear_Ted]

If you ever saw the disassembled impeller of a -044 type fuel pump you would be convinced the pre-filter is a good proactive thing to do.

[SalParadise]

You don't need to use any cleaners in the tank if that's what you mean. If it's rust-free, new gas is fine. If it's rusted inside, buy a new tank.

You are sitting on a fireball if you do not do the tunnel fuel lines in your '74. My '75 which was made in '74 had very, very brittle lines - and it was a CA car. You need to get this done.

[Bob Kontak]

Originally Posted by chrismorse

It is finally up on a lift. What cleaning/flushing materials/techniques should I use??

Just talking.....

Drop the plug and screen. Use a five gallon bucket and an old t-shirt to filter.

Kero or diesel and a $20 garden sprayer from Lowes. Go in from the gauge hole and filler neck and spray away. Go up from the drain hole as well. See what comes out.

Repeat until clean.

I have never done this on a 911 but it seems logical.

Wait until others respond.

[chrismorse]

Thanks Ted, Sal and Bob,
Will definitely replace ALL of the old lines, do the pre filter, and get out the garden sprayer to clean things up.
I'm thinking I need to see what the in tank filter/debris looks like to determine how to proceed from there.
Looking forward to hearing about others experience with this muck.
Thanks
Chris

[SalParadise]

My total experience was this:

Car sat for 20 years. The original '74 tank was very rusted - but the past owner was smart enough to put a pre-filter in AFTER it smoked the stock pump (located in back).

Heaved the tank in the trash. Bought a new tank here on Pelican.

Fuel dizzy was seized. Bought a rebuilt one. Replaced:

1) Fuel dizzy
2) Accumulator
3) All 6 Injectors
4) All injector seals INCLUDING the injector sleeves peened in
5) WUR rebuilt
6) All fuel lines. The return out of the tunnel on my car (Oct '74 build) broke like old licorice.
7) New pump (again).
8) Replaced cheesy plastic injector lines with steel SC lines (seriously, lots of polymid in that engine compartment - too much if you ask me).

In essence - everything replaced.

I am a huge CIS fan. Love it. It's very reliable when it's done right - and you don't cut corners. I would not replace the CIS. Flojo (in Germany) runs his with high HP. You gotta love CIS.

However you cannot take short-cuts and cheese the CIS system because every part of it has to be up to snuff.

[Bob Kontak]

Originally Posted by chrismorse

I'm thinking I need to see what the in tank filter/debris looks like to determine how to proceed from there.

+1. Bet you find the tank ain't that skunky.

Talked a pal with a later 70's XJ Jag (garage queen) into putting Seafoam in his tanks and fill them up.

OMG. The varnish that was caught in the t-shirt when draining was immense. It was not dark crud, it was translucent and plentiful. Like five iterations of filling the tanks and draining to purge.

[boyt911sc]

Chris,

If the fuel tank is free of debris and rust, simply drain the tank of old gasoline. Inspect the tank filter. Cleaned it and reinstall. With fresh gasoline, test run the FP and hook up a battery charger to maintain the battery. You could also run fuel through the injectors by lifting the air flow sensor to deliver fuel to the fuel injectors.

The way I drain my gas tanks sitting on a lift is to loosen the return line fitting to the gas tank. Do not remove the nut but simply loosen the female nut until it starts to drip. Adjust accordingly and place a strip of rag or cloth to divert the dripping fuel to the container. Make sure you have sufficient receiver (containers) to avoid over flow. One time I had two (2) 5-gallon containers and they were not enough. I left the garage for a minute and when I returned the garage floor was flooded. Do not leave the dripping fuel unattended. Or have someone watch it.

Tony

[SalParadise]

It's really not that hard to pull the tank ONCE the fuel has been drained. DO NOT pull a tank with the fuel in it. If it's really that bad, I would pull it and then use Super Clean in the purple bottle, swish it around, and then pour. Then repeat. It will remove everything. It's awesome.

It's really not worth flushing your tank with gallons and gallons of highly combustible fuel in a garage. I would not risk it. I would pull it and wash it out.

[faapgar]

I have always drained the fuel then remove the tank.Seal the drains and add about 3 gallons of Apple Cider Vineger and slosh it around a few times in a 24 hour period.Then rinse with a few bottles of distilled water.Look inside and voila a very clean tank with no residual crud.Fred

[chrismorse]

Thanks guys, I really appreciate all the advice.
Today, I got the car in the air, looked at the supply and return hoses. They are clamped to nipples on the tank. I didn't want to cut or pull off a hose and try to install a drain hose - been there - lots of fuel dripping and spraying about, I'd probably end up wearing a pint or so of the stinky stuff, so took the chicken way out, (since my home abuts the garage, as does a rental and storage garage, not to mention my green car which is going to get serviced and sold to fund the fund the hot rod 911.
Tried using jumpers to power up the car, with the key on to power the pump but no go, so hot wired the pump directly from the new battery. I disconnected the rubber fuel line to the accumulator, ran about 8 feet of hose out the back to two 5 gallon cans in a big plastic tub. took about 10 minutes to pump mostly clear gas into a fiver. I was ready with a couple of buckets of grease sweep, a partially discharged halon extinguisher and a 5 pound dry chemical for back up - I hate gas fires.
Taking the advice on this thread and looking at some of the milky crud that came out, I am going to pull the tank, take it outside, remove the strainer and blow the tank out with my pressure washer, leaf blower and rinse with a quart or two of denatured alcohol.
Ordering the two tunnel lines from Len, two fuel filters a filler neck hose and a tank sender gasket from our Ghost.
More updates after I pull and clean the tank and screen.
Thanks for the advice and support,
chris
Sorry, no pics- having difficulty getting my computer to recognize my iphone.

[Sunroof]

NEVER USE RED KOTE to seal the inside of your gas tank if you have a CIS system.

[SalParadise]

Originally Posted by Sunroof

NEVER USE RED KOTE to seal the inside of your gas tank if you have a CIS system.

Good advice. I would never used RED KOTE - or any coating inside - at all. If it's rusted, and even if you tank it it will re-rust. Buy a new tank.

[chrismorse]

The tank is out, only spilled a teaspoon yesterday moving the drain hose around.
Tomorrow, will drain the last of the gas/debris, then hose it out with the power washer.

Questions, is the swirl pot able to withstand energetic power washing??

Several have suggested apple cider vinegar as a cleaning agent, others, Sea Foam??

From what I can see, the bottom of the tank visible from the sender unit hole, the metal looks to be in good shape, drain it, power wash, rinse with denatured alcohol, (using grain alcohol for the cleaning guy), blow dry and re-install, (after tank refurbishment of coarse).

Guidance appreciated,
chris

[SalParadise]

Vinegar? Surely you jest. Super Clean in the purple bottle at Autozone or cheaper at Walmart. It will remove any residue left by the gas and clean the swirl pot. Seafoam, etc is meant to be run through your fuel system. I have used Super Clean on probably 20-30 motorcycle gas tanks and they come out like new. This stuff is no joke. It's not like a joke like Simple Greene or the rest of the nonsense. This stuff actually pulls the crap out of the metal.