"Laying Up" a fuel pump

[mdsalemi]

Bob Possel's fuel pump for sale, and Greg Bellware's quest for help on a fuel pump issue has me thinking...

How do you "lay up" a working fuel pump for long-term shelf storage?

Eventually, the residual petrol/gas in the pump will turn to sludge/varnish, which might cause more issues. So, what do you do, how do you do it (off the car), and what products do you use?


Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[merrill]

there is a product called sta-bil that is supposed to preserve fuel.
not sure how well this would work long term

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[mdsalemi]

quote:Originally posted by merrill

there is a product called sta-bil that is supposed to preserve fuel.
not sure how well this would work long term

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

Well, Sta-Bil is a fuel additive, not something designed to lay up a fuel pump...I buy large quantities of that stuff every year to put it in the car and the boat's fuel tank.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[ja17]

Hello Michael,

Squirt a little two cycle oil or ATF into the intake of the fuel pump.

Joe Alexander
Blacklick, Ohio

[Shvegel]

Two suggestions:

Use the same flud that injection pump builders use to store pumps. It is the fluid they use on the flow bench to test pumps after rebuild.

Or do what I do. I use Automatic Transmission Fluid. This highly engineered fluid is a great cleaner,corrosion inhibiter and lubricant. I feed it into the inlet while turning the pump(assuming injection pump and not electric pump) until it comes out of the outlet fittings then cap everything off, remove the side cover and fill the lower pump cavity with ATF as well.

[bpossel]

I put ATF in the pump before I put it away.
B.

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[George Des]

The new style pump is a "wet pump" and the "can" is normally filled with gasoline. This pump is very difficult to empty completely without removing the "can". The older pump is a dry pump and gasoline is not supposed to enter the "can"--it will though on a "leaker" which should either be rebuilt or replaced before it leaves you stranded. Either pump will suffer from "gelled" up gasoline if it is allowed to sit in the pump over time. The best thing to do with either pump is to either use the pump immediately or disassemble to the point where you can empty of all fuel if keeping it on the shelf for use later.

George Des

[bpossel]

Hi Mike,

  Thanks for bringing this topic up!  Since my car will be out of commission for 6 months during the repaint, and my new fuel pump is now on the self, I didnt really do anything with it...  I emptied, cleaned and oiled my other pump (the one now for sale) because I planned to keep it for a long time, as a backup, spare.  Didnt think about the one that I just removed...

Thanks!
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[waqas]

Ok, now that we've determined the consequence of leaving a fuel pump (either old or new style) sit for long periods without drainage, what's the remedy after the fact? What kind of solvents can be safely used to clean-up said "gelled" pumps after they've been inactive for a length of time?  Should one simply submerge the entire unit (in the case of the new kind) into a large jar of some kind of solvent?  Or does each piece have to be dismantled and hand-cleaned...?

Waqas in Austin, Texas

[George Des]

My advice would be to dissassemble and clean it out. With the new style pump, this is pretty easy and all you'll be replacing are the -o-ring seals unless you find other problems in there that you may want to fix--like worn down brushes. With the old style pump, you can try running lots of clean gasoline through it in the hopes that it will flush everything out, but I can tell you from pulling dozens of these apart, the two chambers covered by the side plates really get gunked up badly over time. If not leaking, you can try partially disassembling for a more thorough cleaning. It's just that there is a high probabilty of doing more unintended damage to this pump since the bottom plate and side plate screws have a real tendency to break off when trying to remove them. The side plates and bottom have to come off to do the cleaning properly and if you can get it this far, you might want to go the extra step and do a rebuild it while it's apart. Hope this helps.

George Des

[mdsalemi]

quote:Originally posted by George Des

My advice would be to dissassemble and clean it out. With the new style pump, this is pretty easy and all you'll be replacing are the -o-ring seals unless you find other problems in there that you may want to fix--like worn down brushes...Hope this helps.

George Des

Hello George,

Yes it helps very much.  When you say it is easy to disassemble I'm game for trying.  I can get any kind of O-rings, but where does one find the brushes?  As long as I have it apart and clean it all up I may as well change the O-rings and the brushes...

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[enochbell]

Michael,

George has been working with me to get my pump rebuilt.  He sent a kit of rebuild parts, including the brushes and bearings and all of the seals and replacement cheese-head screws to replace the ones you will probably damage when you remove them from the pump.  I would highly recommend you seek his advice and direction on setting the pump for long term storage.

In the meantime, and I am going out on a limb here, but why not use a very light oil and spritz it on the moving parts in the pump.  I don't know the weight specs, but either a high quality clock or gun oil should do the trick.  I have used both, and they will not gunk, in my experience, unless they are exposed to dirt which should not be a problem with a sealed pump.

Best,

g

'64 230sl, fully sorted out...ooops, spoke too soon

[George Des]

Michael,

There are repair kits available from MB sources for the newer, small style pump that will contain the brushes. You can also special order these from a number of brush manufacturers--you'll need to carefully measure the originals and specify a copper-carbon type brush. On the smaller pump you just need to make sure that the brushes have a small cut-out where the brush shunt wire enters the brush. Otherwise you'll have a difficult time slipping the brushes under the brush holder to solder them in place. You'll see what I'm talking about once you disassemble and take a good look at the original brush. Repair kits and brushes for the old pump are not available through MB. The brush dimensions are different on the older, large style pump, and you don't need to worry about this cut-out on the larger, old style pump.

George Des

[waqas]

The brushes are annoying to replace, and unless they show visible signs of wear, I would leave them in.  Getting the can dismantled again would be easy once you've replaced all the old bolts with slotted stainless steel!

Waqas in Austin, Texas

[George Des]

With the proper sized desoldering and soldering iron and the correct brushes, their replacement is no big deal to do. The key on the small pump is to make sure the brushes have that cut out I mentioned or it really will be annoying to try to replace them. The only other thing to watch out for is the correct orientation of the brush springs.

George Des