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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: craig on December 12, 2012, 07:51:49 PM

Title: K75 Fuel Damper / Fuel Pump
Post by: craig on December 12, 2012, 07:51:49 PM

Last summer I started working on my 92 K75S and discovered the fuel damper had disintegrated.  I ordered a new damper but was unable to work on the bike until just now (school intervened).  After hours of cleaning up, I'm ready to reassemble, but I can't see how this damper will fit on the stock fuel pump.  Are there different sizes of dampers?  Are there different size fuel pumps?  I can't compare it to the original because the original has disintegrated! The fuel pump I have (Bosh 580 463 999) has an OD of 5.5cm and the damper has an ID of about 4.5cm. Any info would be appreciated.

Title: Re: K75 Fuel Damper / Fuel Pump
Post by: frankenduck on December 12, 2012, 08:09:52 PM

Yes, 93 and earlier had a larger diameter fuel pump and hence vibe dampener.

Older, larger vibe dampener: 16121464628

Newer, smaller: 16121464694

Title: Re: K75 Fuel Damper / Fuel Pump
Post by: craig on December 12, 2012, 08:35:12 PM

Thanks for the info.  So, it seems like I have an older operable fuel pump and a newer unusable damper.  ~$80 for a new (older) damper or ~$50 for a new alternative fuel pump...? Meh.

Title: Re: K75 Fuel Damper / Fuel Pump
Post by: frankenduck on December 12, 2012, 08:59:41 PM

I don't know where you bought it but my dealer's parts guys are great about letting me return parts purchased in error or not needed.

Title: Re: K75 Fuel Damper / Fuel Pump
Post by: detbmw on December 12, 2012, 09:58:00 PM

After I bought my K75S I wanted to check my fuel damper for any signs of break down. I found an ethanol-resistant damper at Bob's BMW and decided to replace it.
5/85 ->12/92:
http://store.bobsbmw.com/product/fuel-pump-vibration-damper-value-585--1292 (http://store.bobsbmw.com/product/fuel-pump-vibration-damper-value-585--1292)

01/93 ->:
http://store.bobsbmw.com/product/fuel-pump-vibration-damper-value-0193-- (http://store.bobsbmw.com/product/fuel-pump-vibration-damper-value-0193--)

You should never have to replace it again.

Rich

Title: Re: K75 Fuel Damper / Fuel Pump
Post by: frankenduck on December 12, 2012, 10:07:22 PM

It isn't the ethanol that breaks down vibration dampeners.  Its the water ethanol pulls in if the bike sits for a long time that degrades the rubber.  If you ride your bike often or use a good fuel stabilizer (Sta-Bil marine) then there won't be an issue.

There's even a BMW TSB (technical service bulletin) out there that indicates 10% ethanol is fine in K bikes.

http://www.automd.com/tsb/bulletin_b266841/ (http://www.automd.com/tsb/bulletin_b266841/)