Longish story, but I've been restoring a couple of K-bikes. At the moment I've got a k-100 as a project and an extra K-75 parts bike with a fuel tank. Is there any consensus on  the best way to store a fuel pump? I've been under the impression it was best to keep them stored in fuel. Which is what I've done in the past. With the pump removed from the bike I stored them in a paint can (never had paint in it) in a bath of fuel. But I just got in a discussion with another rider who feels that they should be stored dry as the current gasoline/ethanol mixture used here in the states decomposes and accelerates the decomposition of the vibration dampener. For anyone who's not torn one apart, the fuel pump is held in place by a rubber vibration dampener which fits around the pump and which in turn is bolted to a plastic ring which actually holds the fuel pump to the tank. [(An aside) the plastic ring which frequently will break is actually fairly cheap as BMW parts go. The one I bought a week ago cost USD $11. From a BMW shop which is actually cheaper than what EME sells them for.] The dampener on the other hand is rather pricey.

But the basic question I'm asking would it be better to pull the pump and store it dry or to keep it in a fuel bath? I've never had a pump apart and have no idea what its internals are made of and whether or not it is desirable to keep it wet. I just made the assumption that once it had been in fuel it was best to keep it covered in fuel. And which would be best for the dampener ring? Does it disintegrate any faster wet or dry? Any comments?

thanks and best regards,
J.Jefferies

I've still got my OEM pump that I replaced with a Chinese one quite a few years ago. I was told that if I left OEM one out the seals would dry out and it would leak on recommissioning. So as I didn't want to store it in fuel believing that it could also cause problems I went another route. I flushed the old pump out with distilled water and once clean and dry I sprayed heaps of PTFE lubricant into it and wiped of the external excess. I then wrapped it in cling wrap and the stuck it in two zip lock bags. Time will tell if my over kill has been successful.
Regards Martin.

First, how long are you storing it?  A year or so of idleness should be no big deal.  Just run out the fuel that may be in it and put it in a ziploc bag.  Heck, unless you are stripping and painting the tank or doing a serious cleaning of the interior, I would just run it dry on some corn-free fuel and leave it in the tank.  Rinse the mount and the vibration damper with a little S100 cleaner or Dawn dish detergent in warm water and let them dry before you store them.

Longer term I would run the fuel out of it and then run a little ATF(automatic transmission fluid) through it and put it away in a ziploc bag.  I like the ATF because it has additives that help prevent corrosion and keep the seals soft.  Also, it won't evaporate and leave the internals dry and/or gummy.

To run it through just put some ATF in a container, put the pump in and connect 12v.  Make sure you have a hose connected to the outlet that will take the flow to a container like a gallon jug.  Run the pump for a few seconds and it's done.

As long as you don't leave it sitting for 5-6 years with E10 fuel in it you should be good.

My OEM one hs been in storage since July 2017. Does it still work I've got no idea. One day when I've got nothing to do and have the inclination I might give it a go. But I can see why it won't.
Regards Martin.

How long will the pump be in storage? I'm currently shooting for next year for the K100 and who knows for the K75 one. But then my silver K75 bike was bought for my last wife and after she split (while the bike was in bits and pieces) it sat for 7 years till the pandemic gave me a rationale for spending time on it. ATF fluid does sound interesting. Biggest issue is that I don't want the dampener to disintegrate. I've seen them after they start turning to rubbery goo. Not a pretty sight or anything you would want to use again. Question does anyone have a clue as to what ATF might do to rubber? Would kerosene or some other hydrocarbon fluid be better?

thanks
J.

If the damper is going to be idle for an extended period, the best option is to just clean it well with a good cleaner and put it somewhere dry.  My understanding is that it is the ethanol and the bacteria that breed in it that destroys rubber bits like the damper.  The ATF is just a preservative for the internals of the fuel pump.

Point-Seven-five wrote:If the damper is going to be idle for an extended period, the best option is to just clean it well with a good cleaner and put it somewhere dry.  My understanding is that it is the ethanol and the bacteria that breed in it that destroys rubber bits like the damper.  The ATF is just a preservative for the internals of the fuel pump.

Now that's something I hadn't thought of. Just afraid to take it apart too much for fear of getting it back together.Does the pump just sit in the dampener? I noticed that the last one I installed the pump would turn in the dampener. Didn't think about pulling it apart.

Still ,has anyone taken one of the pumps apart? Is there anything inside that would be damaged by gasoline or the gasohol?

thanks all.
J.

I pulled apart a mates non functioning pump. The damper had turned into Vegemite. Externally once the Vegemite was cleaned up it looked OK, but no life in the pump. We removed the aluminium housing and the the armature had rusted and pretty much all the internals were toast. His bike had been run on E10, it was also suffering from pin holes in the tank.
Regards Martin.

The pump is a friction fit in the damper with two embossed rings to position it.  It's easy to get it in and out of the dampener when the dampener is removed from the plastic mount.

MartinW wrote:I pulled apart a mates non functioning pump. The damper had turned into Vegemite. Externally once the Vegemite was cleaned up it looked OK, but no life in the pump. We removed the aluminium housing and the the armature had rusted and pretty much all the internals were toast. His bike had been run on E10, it was also suffering from pin holes in the tank.
Regards Martin.

Ehh, That looks like some I've seen. BTW, I've seen posts regarding E10. Is that the same as gasohol here in the states? A mix of gasoline and ethanol?

But when you looked at the internals of the pump, what were they? Just wondering if there were a lot of plastic or rubber bits that could/would dissolve like the vibration dampener.

thanks
J.

Martin's E10 is the standard swill dealt in your local gas station.  It is blended with up to 10% ethanol.

If you have a "Flex Fuel" vehicle, you can also use the E85 stuff that is 85% ethanol.

If you look real hard and are willing to pay a lot more you can maybe find and use non-ethanol that is 90 or 91 octane and contains no ethanol.

jjefferies wrote:

Point-Seven-five wrote:If the damper is going to be idle for an extended period, the best option is to just clean it well with a good cleaner and put it somewhere dry.  My understanding is that it is the ethanol and the bacteria that breed in it that destroys rubber bits like the damper.  The ATF is just a preservative for the internals of the fuel pump.

Now that's something I hadn't thought of. Just afraid to take it apart too much for fear of getting it back together.Does the pump just sit in the dampener? I noticed that the last one I installed the pump would turn in the dampener. Didn't think about pulling it apart.

Still ,has anyone taken one of the pumps apart? Is there anything inside that would be damaged by gasoline or the gasohol?

thanks all.
J.

If you want to see the pump pulled apart…take a look at the forum tech pages: Mechanical/fuel pump disassembly (photos)…(about third from top).

On pulling the pump apart everything made of ferrous metal had turned to rust. Armature and brush holders seriously rusted out. You couldn't tell if there was anything else in there. The bike had been sitting for I don't know how long. I'll have a look for it when I go over to my mates place it may still be around.
Regards Martin.