AWR-fix: Siphon pump repair

[andrewwynn]

EDIT: another member did an amazing more detailed step-by-step to do this process. I recommend reading my thread for additional information then use his thread add the recipe to follow. The thread is here:

https://r.tapatalk.com/shareLink?sha...0&share_type=t

So tonight when I was about to take a 3 hour drive up north, I go to a pit stop on the way and my car stalls with 18 liters of gas.

Being the self proclaimed master of the BMW X5 fuel system, I figured it was the universe giving me my chance to prove myself.

After three or four start attempts that went nowhere I double checked that the fuel pump which is less than 1 month old was working.

I could hear the hum of the pump from under the car for 3 seconds I knew it was getting power I wasn't sure if I was making pressure.

I pulled up test 6 from the hidden menu and sure enough it had about 17 liter of gas on the left and 0.0 liters of gas on the right.

This points to an obvious problem in the siphon jet.

I put in about 4 gallons of gas so I could get home. I took out my rear seat, open up the left side of the tank and holding the tank open a little bit turn the key to the on position. I was recording with a camera with video so I could share with the group. I will find out soon enough if liquid proof includes gasoline as my iPhone got sprayed with gas.



Here is the main reason the O-ring just popped right out of the groove just like my wife's car.

It was my primary suspect and I was planning on redoing that o-ring.

I replaced that O-ring and did another test. Not at all surprising to me the useless seal in the other connection had failed as expected. It was only leaking maybe 5% as much as the huge leak from the O-ring it was bad enough that I wanted to fix it and figure out a good way to show other people they can fix it easily.


Here's the new o-ring in place


Here is the useless seal taken apart. Be careful taking this apart I use a piece of wire to hold open the one clip at a time as I pried it apart. If you take it apart carefully enough you will not have to create a new way to hold it together. If you break it taking it apart don't worry you can use a hose clamp to hold it together when you're done.

Be very careful about the spring and the one-way valve I almost lost the part as the spring shot it across my car.





The female part is .2 millimeters bigger than the male part so of course it leaks under pressure.

Rather than build an O-ring Groove which is a great solution I wanted a quick and easy solution


4 wraps of fastape Teflon tape folded in half so really eight layers gave me a nice tight fit that does not leak a drop.




Here is the "useless seal" reassembled. Notice that it's a perfectly tight fit. Gooder (sic) than new.





And I think part of why these all fail is because of the way it is held together. The O-ring seal is being held way offset. I added this little zip tie to help hold the O-ring tighter. Normally there will be quite an angle and the side with the O-ring will be about 1.5 mm lower. Zip tie acts like lever on the fulcrum in the middle and holds the fitting around the O-ring tighter.



Yes that's the hose clamp down in the bottom of the gas tank! Be careful not to drop crap into the gas tank.



While I was rebuilding the old ring I sealed that the tank with a piece of an old glove stretched over the opening.

In the morning when I go to do my three-hour trip up north, I will bring a gas can a long and drive down to single digits to make sure my siphon pump is working. Since about a half a gallon a minute less is spraying out the side, I am quite confident in the repair!