Best way to clean gas tanks & fuel lines? '73 610

[610StaWag]

The tank hadn’t had gas in it for a few years, and I tried the gravel thing. I put about 7 gallons in the tank a couple months ago. Recently I tried to get the engine running, but no gas got to the carb. The fuel filter had a couple specks of black material. Well today I decided to drain the tank. I undid the bolt but nothing came out. I put a few more gallons in, but only a tiny trickle came out. I poked the hole and wham, the gas came out with far sized pieces if black material. I couldn’t believe how much crud came out. Is it a fair guess to think that the gravel cleaning attempt did nothing because everything was dried out and hard, and when the tank sat for a couple months with fresh gas the crud all loosened? So I need to clean the tank more thoroughly now. Is there a better way to clean a tank? Before I remove the fuel level sensor (and break the seal), what is used as a sealant or gasket when I put the FLS back in? I have not found a source for replacement tanks; does anyone out there know of a source?

 

I blew air through the disconnected (from tank and carb) fuel line from carb end to tank end. Not much, a very tiny bit of debris came out. Then I put some gas in the line and used compressed air to push it through.  More debris came out. I repeated this going in the opposite direction.  After this I put just air through and held a white paper towel over the end and saw small amount of dark tan staining. I then alternated holding my finger on the line and letting the air flow. Each time there was a small amount of; I guess very fine dust, which left a tiny amount of tan on paper towel. There were no discernable pieces, not even a grain of sand or debris. What should I do now? Is it good enough? Do I need to replace the entire length of gas line?

 

When I took apart the fuel inlet to the carb I found no trace of debris. Since sight glass level was below halfway, I put a tiny bit of gas in by hand. The glass did fill, and the float did go up and down when I pushed on it. But when worked the throttle, there was still no squirt of gas. What do I do now?

 

 

[Rjawm]

I've used a short length of 1/2 inch stainless chain with a quart of gas and shake vigorously to clear out all the big chunks. 6 to 8 inches long works well from my experience.

 

 

Remember not to be too brutal in the shaking though, don't want to screw up pick up tubes and such.

 

Then drain, swish around some more gas without the chain to get the last of the crap out, drain again.

 

Then use this POR kit to refinish and seal the inside of the tank.

 

 

http://www.por15.com/POR-15-Fuel-Tank-Repair-Kit_p_62.html

 

Worked awesome for me on a couple old VW's, some muscle cars, and a 720.  The muscle car tanks sucked because of the size though.

[tr8er]

I used the POR15 product per instructions. I'm actually still satisfied in the process and would do it again, but a word of caution: Do not use it in high humidity or you will get results looking like mine with bubbles all in it.

 

[datzenmike]

You can re-use the O ring or just take it to an auto supply store and get a match. Not rubber though, get neoprene or viton, something impervious to gas.

[TENDRIL]

muriatic acid and some sort of abrasive material,  or take it to a radiator shop have them give it a good steam cleaning. I have taken the sensor out of my 510 multiple times and the factory o-ring is still just fine and seals every time 

[Stoffregen Motorsports]

Any advice I can give would be wholly dependent on how bad the tank is and what it is you're trying to achieve.

 

If it's really bad, I wouldn't waste my time, I would just bring it to a radiator shop and have them do their thing. The process at the radiator shop will remove the outside paint so if you're trying to leave that alone, it's not a good choice. If you want a restoration quality refinish, take it from them "bare metal" and paint it yourself.

 

If it's not that bad, I would install an extra fuel filter and let that get clogged up. Running good gas through the tank for a few fills is usually enough to clean out any old sticky stuff.

[Lockleaf]

FWIW, a different tank coat called red kote recommends just rinsing tanks with CLR, then water, then done.

[ddrum]

I used Lacquer thinner to clean my gas tank. The car had been sitting since 1990 and had about a gallon of old black gasoline in it. I poured a gallon of thinner let it sit for an hour or so and rinsed it. all the black tar looking stuff at the bottom of the tank came off really nice.

[HOGIE]

Best way is to clean fuel tank is to have it hot tanked and acid dipped. That's what I do for work. Did it on both my fuel tanks and the fuel lines on my 521. Very clean and never had any problems. 

 

I replaced the fue lines on my 620, I'll probably end up doing the lines on the 521 eventually. the old fittings need replacing and I can make things cleaner looking by just replacing

 

 

 

 

Put it in a box and ship it to MetalWorks Paint & Rust Removal

[G-Duax]

I would caution using gas, or any flamable liquid, and hard bits to loosen gunk from a tank.

The cance of a small spark, and you could lose your head.

Rjawm may have been safe, as stainless is less likely to generate sparks.

 

Also not up on people using muriatic acid, as that gives off hazardus fumes.

 

Many years ago I did service work on gas stations all over Texas.

People don't realize how much organtic residue is in gas, stuff that even strong solvents like acetone won't touch.

One thing I did find that will take it right off are cleaners like Simple Green, or the ZEP Purple Power (even stonger).

 

When I did my 620 tank, I used simple green, and about 5 pounds of hex nuts (lind of like doing the gravel shake thing).

[paradime]

X2 ^

[610StaWag]

Thank you everyone! I put this project off because I had no confidence in myself. The posts you have made gave me courage to persevere.

 

I contacted a radiator shop and will bring the tank in. When I removed the fuel level sensor I was stunned about how bad the inside of the tank was. A real WTF. Although I dread it a bit, I guess I should replace ALL the fuel lines. Is there any gas line material/steel that is a bit easier to bend (I have been spoiled by working with copper alloy brake lines)? After that, I will buy a new mechanical fuel pump (Nissan parts just discontinued the pump bottom).  Any brand recommendations for a mechanical fuel pump? I could not find any Datsun pump, new or used. And last, the carb goes back to the rebuild shop.

 

Does anyone know what the Ohm meter readings (both up and down) should be for the fuel level sensor?​

[HOGIE]

Radiator shop probably has hot tank. This will dissolve the stinky petroleum goo, it no longer fuel, and whatever paint and undercoat on the tank. Hot tanks don't do anything to rust. If you have a rust issue get a jug of Ospho paint prep rust treatment. Pour it in and swish it around for a couple days changing position. At work we fully submerge parts in acid for 2 days to treat rust