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K100-forum.com » Technical, repair and troubleshooting » Electrical » 1985 BMW K100rs Failing Fuel Pump???

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1Back to top Go down   1985 BMW K100rs Failing Fuel Pump??? Empty 1985 BMW K100rs Failing Fuel Pump??? Thu Jul 14, 2016 8:52 pm

robdiaz44

robdiaz44
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active member
Thought I'd get some input...instead trying to type it all out...I went this route. If a picture is worth a thousand words, then a video is worth maybe a couple thousand???  What a Face

I originally shot the videos for a friend (Tim) that has been helping me out with getting my bike going again...but I thought I'd share with some other BMW Kbike gurus. I apologize in advance for attempting to talk while the engine was going in PART 1  Embarassed



    

sidecar paul

sidecar paul
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Rob,
The spring loaded ball bearing is intended to stop fuel coming out of the tank when the fuel return pipe is removed. It was very common for it to make that sort of noise and the cure was (is) to leave the spring out or remove the ball and spring altogether. 

Fitting quick release fittings in the fuel lines makes the ball/spring assembly redundant and makes tank removal a doddle.

I'd try removing the spring before buying a new pump.

Paul.

PS I've been running both my K's without the ball/spring assembly for over 30 years!


__________________________________________________
'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015) 
....No CARS never ever!
    

robdiaz44

robdiaz44
active member
active member
Thanks Paul...I will surely remove the spring and ball bearing first. I removed that valve yesterday, but wasn't sure how to get to the spring and bearing. I gave a feeble attempt (with some needle nose pliers) to remove the "innerds" that houses the spring and bearing...to no avail. Any suggestions as to how to do this?

    

92KK 84WW Olaf

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My LT has one in but the 84RT does not have any. I imagine fitting a quick release connector [not the BMW plastic one] would be a preferable and probably cheaper option.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

sidecar paul

sidecar paul
Life time member
Life time member
Hi Rob,
Just back from my camping weekend, so sorry for the delay in replying.

You need to lever out the plate that retains the spring; if you want to leave just the ball in place, the plate can be refitted and the rim of the fitting can be peened over to retain the plate.

Paul.


__________________________________________________
'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015) 
....No CARS never ever!
    

robdiaz44

robdiaz44
active member
active member
Just out of curiosity...would this ball bearing/spring malfunction in the return valve cause the bike to not start? I left town for a few days...went out to the garage to fire the bike up...now it does not start. It turns strong, but does not fire up.

    

Motorbike Mike

Motorbike Mike
Life time member
Life time member
I had the same noise on a bike I rescued after been stood for many years. The spring had gone rusty and collapsed taking the correct tension off the ball and this caused the screeching noise. I had no choice but to remove the broken spring and the ball. I've since found a replacement spring but not yet fitted it.
As mentioned above, this is only a non return valve to stop fuel coming back down the return pipe when you remove the tank. If this is is a problem either syphon the tank or fit a dry break coupling. These are really handy and I have 2 on my Cobas Flying Brick.

1985 BMW K100rs Failing Fuel Pump??? Dry_br10

    

robdiaz44

robdiaz44
active member
active member
Thanks every one...since my last post, I was able to get the bike started...the noise has not returned. It appears that the sound was the bearing/spring in the return valve.

    

robdiaz44

robdiaz44
active member
active member
Motorbike Mike wrote:
As mentioned above, this is only a non return valve to stop fuel coming back down the return pipe when you remove the tank. If this is is a problem either syphon the tank or fit a dry break coupling. These are really handy and I have 2 on my Cobas Flying Brick.

1985 BMW K100rs Failing Fuel Pump??? Dry_br10
Thanks Mike...I've resulted to siphoning the tank during my recent troubleshooting ventures...does take a while though. These fittings look to be a worth while investment.

    

Roland5

Roland5
active member
active member
sidecar paul wrote:Rob,
The spring loaded ball bearing is intended to stop fuel coming out of the tank when the fuel return pipe is removed. It was very common for it to make that sort of noise and the cure was (is) to leave the spring out or remove the ball and spring altogether. 

Fitting quick release fittings in the fuel lines makes the ball/spring assembly redundant and makes tank removal a doddle.

I'd try removing the spring before buying a new pump.

Paul.

PS I've been running both my K's without the ball/spring assembly for over 30 years!

Do you (or any others) have a pic of the quick disconnects (QD) on the bike?  I have some different QDs and wasn't really comfortable with my spacing options for the tank lines.  I would appreciate some examples.  Thanks


__________________________________________________
Roland Antumblen
85K100RT - BlacK Beem
Toad Suck, AR
    

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