Author Topic: Compressed air to clear output tube from Gas Tank?  (Read 6326 times)

jf308

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Compressed air to clear output tube from Gas Tank?
« on: October 02, 2014, 21:00:02 »
PLEASE don't tell me that I have to remove the gas tank again !! LOL

Long stored 64 SL.  I removed the Gas Tank and drained the old fuel/varnish, rust particles, etc.   Sloshed new gas around and re-drained at least 25 times until the majority of the small particles disappeared.   

I did not have the 22MM hex lug to remove the Drain Plug, but was hopeful that this would do the job.  Painted the exterior of the old tank, and re-installed.  5 gals of fresh fuel.
Tried to get fuel to the IP lines (I am also trying to free up the IP pistons).   Nada.  Removal of the hose to the fuel pump.  Nothing flows/drains from the tank. 

20 lbs of compressed air back thru the line.  You can hear the bubbles in the tank -- but still no fuel will flow out.  Just a very small drip.

SHOULD I DRIVE MORE AIR PRESSURE THRU THE OUTPUT LINE from the tank? Other solutions? 

Do I have to re-drain the gas and try to find a way to remove the 22M drain plug to perhaps clear the flower pot screen?

UGH.

Jordan

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #1 on: October 02, 2014, 21:26:47 »
It sounds like the hole feeding fuel into the flower pot inside the tank is plugged or severely restricted.  Do a search on "flower pot" and you will see pictures and explanations on how it works.  The hole at the base of the flower pot being plugged prevents fuel from reaching the fuel lines and 5 gallons wouldn't be enough to have fuel flow over the lip of the flower pot.  You may be getting some seepage which is why you can hear it bubble, but not enough to feed the fuel pump.  I had the same problem and I ended up replacing the fuel tank with a new one.  Yes, not cheap but you will never have to worry about dirty fuel again.
Marcus
66 230SL  Euro 4 speed

jf308

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #2 on: October 02, 2014, 21:43:19 »
I don't quite understand how air would blow back thru the line into the tank with a compressor  (tried 20 lbs, then 40 lbs).... and still not get any clearing of the line.  Fuel still does not flow outward.  I may try to weld up a 22MM drain plug removal tool....and see whats inside

Just in case:  Best place to source a new tank, if I continue to fail miserably?  How much will this cost for a new one

Thanks.  John


scoot

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #3 on: October 02, 2014, 22:22:15 »
use an inverted spark plug socket for the flower pot.  Meaning take a spark plug socket and shove a 12" extension into the spark plug side of the socket.  The base fits the filter.
Scott Allen
'67 250 SL (early)
Altadena, California

66andBlue

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #4 on: October 02, 2014, 22:32:02 »
..  Best place to source a new tank, if I continue to fail miserably?  How much will this cost for a new one ..
Try K&K: http://www.kkmfg.com/catalog_loader.php?page=113/113fuel.svg
Alfred
1964 230SL manual 4-speed 568H signal red
1966 230SL automatic 334G light blue (sold)
1968 280SL automatic (now 904G midnight blue)

scoot

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #5 on: October 02, 2014, 22:46:00 »
I've gone through this recently with a fintail and a Pagoda tank is slightly more complicated but not much.   First of all, removing the tank is not that much of an issue.  So take the damn tank out.  There is an inlet tube and an outlet tube.  Are both clear?   Can you blow compressed air in both?  If not, try wire or a guitar string or soaking the bottom of the tank in lacquer thinner for a day and try again. 

Maybe I didn't read carefully but have you isolated the clog to the tank and NOT to the rigid lines between the pump and the front of the car?   Those also get a good cleaning.  I like a combination of carb cleaner followed by compressed air with an empty 2 L coke bottle on the tank side of the tube/hose.  Repeat until it comes out clean on the lines in both directions.

The most important thing is that you HAVE FUN doing this and not play with matches at the same time.   Oh, and the compressed air can blow back in your face if there is a clog so don't spray your face with carb cleaner, etc.
Scott Allen
'67 250 SL (early)
Altadena, California

ja17

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #6 on: October 03, 2014, 01:56:10 »
Run  a heater cable into the lines to clear them.  Yes remove the drain.  Research the fuel tank in the tech manual for many revelations. Keep asking questions.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

jf308

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #7 on: October 03, 2014, 17:54:57 »
Thanks All.

I AM DEFINITELY having fun learning about these SL's....but am also definitely finding some very weird stuff. 

Having photos of the tank infrastructure in the Forum is helpful as this is strange.

5 gallons of fuel in the tank.   Output tube  open and bottom drain plug out.   NO GAS DRAINING.   Only about 1/2 cup of gas exited the tank.

I am trying the piano wire trick in the output tube.... will see.  Back to re-look at the photos.

:-)  Having fun.


John

jf308

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Re: Compressed air to clear output tube from Gas Tank?
« Reply #8 on: October 03, 2014, 20:38:21 »
Closing this thread and will update progress in the "Bringing 64 230 SL back to life" thread.

With the FI pump off, I wanted to check Fuel delivery to the fuel feeder line.  Fuel pump runs fine.  Seems to pump a decent flow into a 2 gallon tank from a test feed.
Affixed the rubber fuel lines...and the fuel input lines from the fuel tank.  5 gallons of fuel.  NO FUEL FEEDING through the lines.
Tried compressed air back into the tank.  Heard the fuel bubbling, so assume that the lines are clear.

Removed the fuel output line from the tank.  No fuel drainage.
Removed the 22 MM drain plug at bottom of tank.  Minimal if any fuel drainage.

Based on everything else I have read....looks like the fuel input to the Flower Pot is clogged. 

Removed the fuel sender from inside the trunk.  Verified that there is no fuel inside the Flower Pot itself.

Next steps:  Find a way to clear the flower pot input underneath the fuel return line.  Hmmm.  Not sure exactly how.