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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: mac on May 20, 2013, 09:21:47 AM

Title: replacing K75 fuel return lines--what else to buy for the job?
Post by: mac on May 20, 2013, 09:21:47 AM
Looks like a bunch of the intake stuff will have to come off to get at the fuel pressure regulator to make the connections for the return line.

What's the simplest way to gain access to replace the lines? If I wanted to, can I get in there without cutting off any oetiker clamps from the intake manifold?

I'll probably just make it a full-rubber-refresh job, and buy the "bushings" (#4) and clamps (#5, #3). Maybe the crankcase breather hose too.

(http://www.maxbmwmotorcycles.com/fiche/DiagramsMid/B0000149.png?v=04302013)

Anything I'm missing?
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: Inge K. on May 20, 2013, 09:30:11 AM
If you remove the bottom half of the airfilter housing, the FPR would be accesible from RHS.
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: mac on May 20, 2013, 10:08:44 AM
Quote from: Inge K. on May 20, 2013, 09:30:11 AM
If you remove the bottom half of the airfilter housing, the FPR would be accesible from RHS.

The bottom of the air cleaner housing is fastened to the top of the block somehow, right? Do I need to take everything above it off, too?
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: mjydrafter on May 20, 2013, 10:27:06 AM
Inge's correct, go in from the right.  take off the top of the AB, and remover the filter.  Don't forget the large clamp on the rubber elbow (not the one closest to the AB), it hooks the AB to the 2nd airbox in your picture.  You will see, IIRC, 4 bolts to remove the bottom of the AB. You kind of have to leave the top of the AB hanging, unless you want to unhook the MAF wiring.

This sounds a lot tougher than it is, but it's way easier than going in from the left.
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: Inge K. on May 20, 2013, 10:39:43 AM
The bottom half of the airfilter housing is mounted with two 8mm socket head screws.
(small hands, and a short 1/4" ratchet would be an advantage).
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: JamesInCA on May 20, 2013, 03:14:38 PM
The hardest part is getting the MAF wiring off and back on, if you choose to do so. I recommend leaving that in place and unhooking the large air elbow at its other end, as described. You'll have to work around it a bit, but that's probably easier than removing/reattaching.

I recommend getting BMW's shaped return hose for the run from the FPR back to the tank. You can use regular 8mm or 5/16" FI hose (I did), but the routing is awkward and has potential to kink. Plain FI hose will work for the rest. If you're replacing the hose in the tank, the cheapest option is BMW's hose, which they sell by the meter for about NAPA's price per foot for the stuff.

For the small vacuum hose from the throttle to the FPR, 1 ft of 3/16" vac hose from NAPA will do you, but at 99 cents/ft, you might get two, just to have an extra inch or so to work with. Also, the spring protector for that hose is only $2 from BMW, in case yours is thrashed, as mine was.

Lastly, BMW uses one-time Oetiker clamps on the FPR so that you never have to deal with screw clamps coming loose. If you want to replace them with the same, you'll need to buy those, or suitable high-pressure screw clamps if you go that route. The screw clamps are the same size as the ones holding the hoses onto the tank nipples at the front left. Once on the FPR, you can position the top one to be accessible from the left side for tightening, if desired, but not the one on the side of the FPR, which is blocked by the throttle body. The Lisle 30800 is mentioned as a suitable low-cost alternative to BMW's tool for clamping the Oetiker clamps, but I don't have one myself.
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: billday on May 21, 2013, 07:33:50 AM
Everything James said....   Remove the air filter and the snorkel, and you can JUST get a hand a a wrench in to undo the two bolts that attach the bottom half of the airbox to the engine block. Loop a bungee around the top of the bike to hold the top half out of the way. This saves you having to disconnect and reconnect the air flow sensor, a major savings in time and potential screw ups.

You will then have to disconnect the big 90-degree air duct that connects the upper half of the air box to the plenum (in order to remove the plenum), but that's just fussy not difficult.

On Oetiker clamps, two options: Someone here recently posted an inexpensive tool for clamping them, poke around and you'll find it. Or, poke around some more and find my thread on doing this job, which includes McMaster-Carr part numbers for regular old clamps. I like my way because I don't like buying a tool I'll never use again.
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: BGadds on July 14, 2013, 03:59:37 PM
Wow, quite a hassle just to replace a fuel line.  But, as usual, the advice here helped me through it.  Much more useful than the 2 manuals I have.

Hopefully the reassembly will be smooth after I get the new hose in.

Thanks again all........
Title: Re: replacing K75 fuel return lines--what else to buy for the job?
Post by: mac on September 24, 2013, 01:55:13 PM
Finally did this job this weekend. The advice here was golden, as always. Going in from the right by removing the airbox (i left the MAF wiring connected) was clearly the way to go. Ended up doing a bunch of other rubber-refresh at the same time. Ultimately I did:


Also new rider footpeg rubbers and shift lever rubber. I cleared my backlog of long-ago-ordered parts!