F650 GS Fuel Pressure/Fuel Filter FAQ
edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.

The price of the Fuel Filter seems to have gone from US$112, to US$85 to US$65.
The new specs on the fuel filter replacement for the GS has been raised to 24,000 miles rather than 12,000 miles.

Replacing Fuel Filter FAQ
by Robin #790, Photos by Kristian #562

What you need:

  1. Remove the seat, the left faux tank panel, and the center faux tank panel. Refer the GS Fairing FAQ for tips & details.

  2. Take the rubber band off the BMS unit. Put the rubber band in a safe place and lay the BMS unit over to the right side of the bike.

  3. Remove the two circlips and loosen the Torx bolt on the oil tank. You don't need to take it out all the way, but if you do do NOT lose the black spacer. Make sure that you replaced the oil filler cap from when you removed the left faux tank panel. Loosen the oil tank on its moorings (lugs) and let it hang off to the left side of the bike. Tie it up with a bit of string to save the hoses/your paintwork.

  4. This is the fuel filter. Itís under the loop of the frame that the rear of the airbox attaches to. Itís held to the frame by a clamp. Thereís a Torx bolt that runs through the clamp and into a fitting on the frame. Loosen this bolt until itís free of the frame. Now, the only thing holding the fuel filter to the bike are three hoses, attached by three hose clamps.

  5. Loosen the hose clamp that secures the hose on the top of the filter (Marked Red). Iím sure thereís an elegant way to do this, but I havenít figured out what that way is. I wiggled the hose clamp with a pair of pliers until it was deformed enough to loosen. I then disconnected the hose from the fuel filter. Even with a full tank of fuel (silly, silly me), very little fuel escaped at this point. Perhaps a tablespoon dribbled out. Now might be a good time to put your replacement hose clamp on the top line so it will be ready to rock when the top line is connected to the fuel filter. If you forget this step, itís easy enough to just spread the clamp apart and do it after the hose and filter are already connected.

     

  6. There are two fuel hoses connected to the bottom of the fuel filter by hose clamps. (marked green in above picture). One of the hose fittings is located at the center of the filter, and the other is off-center. Remember which is which, or mark them for future reference with a colored zip-tie or some such. I disconnected the off-center one first (because it came off first), but I donít think that it matters which order you disconnect them. When you disconnect either of them, gravity will cause the fuel stored in the filter to run out. You can stop this by deftly covering the hole with your thumb. I then disconnected the line to the center of the fuel filter. At this point, the hose dribbled out gas unless I held my thumb over it. At this point, all of my thumbs were occupied. I believe gas would keep dribbling out of this line until the level of fuel in the tank was lower than the top of the line. This is a very good reason to do this maintenance on a fuel tank that is half-empty. The rest of the fuel in the filter will want to drain out. Remove the filter from the general area of the bike and empty the gas into some safe receptacle. Really mileage-minded folks might save this in a jar and put it back into the bikeís tank. I ineptly spilled it onto the floor of the garage, where the fumes gave me a headache.

  7. WARNING-THIS IS EXACTLY WHY YOU SHOULD DO THIS OUT OF DOORS, IN GOOD VENTILATION, WITH A FIRE EXTINGUISHER HANDY. Also, see if you can refrain from smoking or otherwise giving off sparks during the operation. One more thing; I often use latex mechanicís gloves to keep from getting my hands really filthy. Gasoline eats through latex like nobodyís business.

  8. So now youíve got three hoses connected to nothing. Itís pretty obvious where they should go-onto the new fuel filter! Before you connect them, however, put some hose clamps loosely on the two lower fuel hoses. Itís just easier to do this at this point than connect the hoses, spread the clamp apart, get the tail of the clamp to engage, etc. Also, you should slip the clamp off of the old fuel filter and place it onto the new filter prior to fitting any hoses.

  9. After the clamp is loosely over the new fuel filter, and all of the hose clamps are loosely in place, connect the hoses to the proper fitting on the fuel filter. Tighten the hose clamps. Make sure that the hose clamps have a good grip on the hoses. Weíre talking 50 psi fuel here. No leaks = no barbecued F650 pilot.

  10. Reattach the Torx bolt in the fuel filter clamp to the frame. It should go in easy-peasy.

  11. Replace the BMS unit, and the rubber band which holds it in place.

  12. Wiggle the oil tank back into place, and replace the circlips. Donít forget to tighten the Torx bolt at the rear of the tank.

  13. Replace the left faux tank panel and seat.

  14. Turn the key on and off several times to pressurize the fuel system. Crank the motor. Mine took a few seconds to start, maybe 10 seconds or so. Youíre done! Congratulate self on saving about $85.00 in labor. Ponder installing inline fuel filter to avoid ever having to do this again. Go for a ride!

Replacing Fuel Filter FAQ 2
Bird on Advrider
 

Why would anyone integrate a USD2.00 fuel filter with a USD65.00 pressure regulator? Look carefully folks, this is a USD90.12 fuel filter. Yes, not a typo, a ninety-dollar fuel filter. The Fatherland recommends changing filters every 12k miles, the shop reco's every 20-24k miles. I have about 16.5k and the machine was lurching a bit. It felt like a clogged filter, but who knows. I haven't been out on the highway yet to test.
 

I'll begin with the procedure:


Of course, every bit of maintenance on the Dakar begins with removing about nine-million pieces of plastic. Then, unless you want to remove the intake chamber and oil reservoir, you will be bloodying your knuckles because the mounting strap and bolt are upside-down. Yes, upside-down. Why do I think this? Because when I installed the new one I moved the strap to the opposite side of the welded nut and refastened it in 2 minutes - as opposed to the 20 minutes it took me to get it off.

Then there are the trademark Deutsche-fasteners. Those silly onetime-use crimp hose clamps. This is where I started cursing. Even Ford is smart enough to use a standard hose clamp. There is plenty of slack in the supply and return hoses to pull the filter out to work on the clamps...except they are wrapped around a support brace, negating any available workspace. I ended up making a tool from some old needle-nose pliers.

 

It musta have been Bavarian-smoke-dope-until-yer-fuggin'-eyes-pop-out-of-your-head-day when this beauty was designed.

Here is another pic with a Supertool thrown in for size comparison.

 


 

Being the inquisitive little birdy that I am, I went to work with the 12" non-ferrous blade, dissecting the old filter. The plan was/is to separate the filter from the pressure regulator, keep the pressure regulator permanently in place, and install two inline USD2.00 fuel filters of the standard type. The cutting exercise took an interesting turn when the blade bit a little more than it could chew and sent the filter unit, at mach 4, across the shop. This is why I like to be in the shop ALONE. Liability - and I do more than my share of stupid things in the shop.

 

I ruined a seventy-dollar blade but, kept all of my limbs and digits in tact. I can live with that. What I DID do successfully, before sh*t went south, was separate the filter and regulator. YEEHA!. Now all I have to do is take the regulator and a 30-pack of Keystone to my neighbor machinist and in a couple of days I will have successfully corrected the ninety-dollar fuel filter problem.

 

These parts may be totally integral and I may be totally full of sh*t in which case I've just wasted more of Baldy's bandwidth and some tooling time, but so what I learned a few things. In any case, I have a brand spankin' new BMW approved, Gunther-certified fuel filter under the hood. Effin criminals, those engineers. Effin criminals.

 

Feedback on Filters

F650 GS Fuel Pressure/Fuel Filter Information
by Harold
13-Jun-01

The fuel filter/regulator is one unit. It has been tossed around that a bad batch of these may have been causing the S&S problem, but never really confirmed. So when you go to BMW for your 12K Mile service and they say "We have to replace the fuel filter but unfortunately it is integral with the regulator and will cost you $85, they are not BS'ing you.

The 'wrench' at our dealership just told us this week that at the most recent BMW tech school he attended in late January, the new specs on the fuel filter replacement for the GS is raised to 24,000 mi. rather than 12,000 mi. He also said all the mechanics/techs at this particular meeting said the fuel filter/regulator combo that is so expensive is "bogus" -- I think they're all looking at the post-warranty options out there. I shared with him what I got from this site and he's checking it out. Thanks once again, gang. Hope this will save someone out there $85 -- for now. NancyK#764

You no longer need to replace the $85 fuel filter at the 12K service in order to hold on to your warranty. It took a little bit of convincing on my part, but what convinced my local BMW tech was that the F650CS maintenance literature specifies a 24K interval. Robin #790

Detailed Discussion on the F650 GS Fuel System
by Harold

I am not in the mood to pay $172.00 Canadian ($112.00 U.S.) for a F650 GS fuel filter every 10,000 km (6,000 miles) as recommended by BMW. (Filter Change Interval now revised as above)

I've had a knowledgeable mechanic look at the fuel injection system on my car and on my F650 GS Dakar and point out the differences to me.

Here is what I've been told:

  1. The fuel flow in a typical fuel injection system is as follows: From fuel pump located in the gas tank -->inexpensive replaceable fuel filter --> fuel pressure regulator, where some of the fuel is diverted to the injector (s) and the excess is returned to the gas tank for recirculation.

  2. The high pressure fuel pumps required for fuel injection systems are located in the gas tank for cooling and lubrication (by the fuel itself). This means that if you run out of gas, the fuel pump will run dry, overheat, and will fail either immediately or shortly thereafter. DON'T EVER RUN OUT OF GAS.

  3. Some, but not all, fuel pressure regulators have a non-replaceable fuel filter built in that acts as a SECONDARY fuel filter to trap any dirt particles that get into the system when the PRIMARY fuel filter is being replaced. The typical fuel pressure regulator should last a long time, typically for the life of the vehicle, unless it gets clogged up with dirt, or rubber particles, shed when aging fuel hoses crack internally and are flexed to replace the primary fuel filter. For this reason, it is prudent to replace the rubber fuel hoses at the same time as the primary fuel filter to prevent clogging up the expensive fuel pressure regulator with cracked rubber "chips".

  4. When replacing fuel hoses, you must make sure that you purchase the high pressure fuel hose designed for fuel injection systems, and not the common fuel hose designed for gravity feed systems. The high pressure fuel injection hose costs approximately $4.00 U.S. per foot (minimum). If you are paying less than that per foot, you are buying the wrong fuel hose that will rupture and spray fuel all over as soon as you turn on the ignition key.

  5. The regulated fuel pressure to the fuel injector on the F650 GS is 3.5 Bar (50.75 pounds per square inch). The fuel pump is capable of developing a pressure much higher than that. The fuel system remains under HIGH pressure at all times, even with the ignition off and the bike left unused for many days. Wear safety goggles and protective clothing at all times when working on it. Hoses under pressure can slip off, spray fuel, and fling hose clamps off their ends at velocities approaching that of a speeding bullet without any warning. Flying hose clamps can create sparks and ignite the fuel spray when they hit a solid object. Work outside in a well ventilated area with a fire extinguisher handy.

  6. Unlike my car, the F650 GS does not have a PRIMARY fuel filter and relies on the filter built into the fuel pressure regulator. In this case, to replace the fuel filter, you actually have to replace the very expensive fuel pressure regulator itself. BMW's recommended replacement interval is 6,000 miles / 10,000 km.

I am becoming convinced that the fuel system on the F650 GS was designed by someone who flunked out of engineering school, and I have no intention of paying for their mistakes through the purchase of fuel pressure regulators (mis)used in place of fuel filters. The fuel filter for my fuel injected car costs $19.95, installation labour included. Paying BMW ten times that amount for my motorcycle filter is not going to happen.

We found years ago on the early 1100's that setting the proper voltage on the butterfly readings would dramatically control how the bike ran. Rich vs. lean, etc.. I don't recommend that you try this without your understanding that its a problem area you may have to get back to dealer to fix, BUT... Those of us that have been there on the 1100's have figured it out to a point of no longer needing the dealer to get past the settings I speak of! A digital voltmeter is necessary and the pickup for the Motronic is on the side of the throttle body. You have to figure out which wire is the low rpm circuit and access it (a BMW wiring program for this model would help a lot!) Also, you have to know in advance the proper setting from a currently perfectly running 650. A lot to ask, but I believe it can be problem solved with the right charts and meters without changing any chip or other hardware. I may be all wet here and those more electrically knowledgeable will no doubt key in on this, so have at me! All I know for sure is that I've accomplished this on my R1100 and its perfect beyond anything the dealer was able to do for me! One more thing; the Motronic has to read a certain voltage imput from the butterfly position inside your throttle body to run properly. You find the data link to know this setting and you are home free. Its adjustable on the older bikes. Check your new 650's and see if the throttle body has a electrical pickup on the side of it and if it has two allens screws in it. There you are. I'm not sure on the new 650's, so look! I know warrantee is in place, so most of you will not ever challenge the system here, but the earlier days of this electronic stuff left us without much choice if we wanted to get it right, we dug in. The dealer guys just could not get it done! Rob Lentini of BMWMOA fame has done much research on this topic (R1100 related) and would be another to contact if so inclined. Good luck...

I also had an interesting conversation with a high ranking engineer from a major auto parts manufacturer. Here are the highlights of the conversation:

The F650 GS fuel filter/pressure regulator device, BMW P/N 13 53 2 343 565, is manufactured by a competitor of theirs, a company called Kolbenschmidt Pierburg AG
http://www.kolbenschmidt.de/ and http://www.msi-motor-service.com/deutsch.html.

The device is an auto industry standard 3.5 Bar fuel pressure regulator "canned" with an auto industry standard fuel filter. Because of the unique packaging, BMW was able to place it under patent protection. Even though Kolbenschmidt Pierbug is a major auto parts manufacturer and is geared up to flood the market with millions of these devices for resale under third party brand names, BMW won't let them. (Actually, rumour has it that there is something about license fees / royalty fees that are prohibitive.)

Precision engine manufacturing techniques combined with the precision of digital electronic engine controls, have resulted in engines being built that require fuel to be delivered at a constant pressure with a variance of no more than +/- 0.10 Bar. Previous long term capital investments in current production machinery, combined with the use of materials selected for affordability, rather than optimal suitability, place constraints on the accuracy with which a fuel pressure regulator can be built. The current off-the-shelf auto industry standard fuel pressure regulator has a maximum variance of +/- 0.20 Bar. Statistical analysis of plant production data suggests that 1 in 3.5 fuel pressure regulators do not meet spec if measured against the higher +/- 0.10 Bar variance constraint. Digital engine controls can somewhat compensate for the "out-of-spec" regulators, depending upon the number of power strokes per crankshaft revolution. For example, a V8 engine has 4 power strokes per crankshaft revolution and thus has 4 compensations per crankshaft revolution. A four cylinder engine has 2 power strokes per crankshaft revolution and thus has 2 compensations per crankshaft revolution. A single cylinder engine has only one compensation per two crankshaft revolutions. An out-of-spec fuel pressure regulator that can not be compensated with engine electronics, may cause surging and stalling. A quick and dirty solution is to increase the rotating mass of the engine (larger flywheel).

Fuel pressure regulators are built in batch lots. There is very little variance between regulators from the same lot; however, there can be significant variance between different lots. This variance is due to the initial production machinery set up and adjustment for the manufacture of a production lot.

What does all of the above mean for an F650 GS owner?

  1. After you have finished messing around with reprogramming the FI system and changing fuel injectors, and you find that you are still having problems, you might want to replace the fuel pressure regulator to see what happens.

  2. If you have a perfectly running bike that over a period of time begins to develop a surging / stalling problem, you may have developed low fuel pressure due to a clogged fuel filter. Replace the filter/regulator device.

  3. If you take a bike that purrs like a kitten in for service and take out a bike that behaves like a constipated donkey after they change the fuel filter, you may have just become the proud owner of an out-of-spec fuel pressure regulator that came bundled with the new fuel filter. Solution: Insist that the dealer save and return the old/used fuel filter/pressure regulator device to you when you take the bike in for service. If you discover you have after service problems you didn't have before, reinstall the old fuel filter/pressure regulator and see if they clear up. If they clear up, the culprit is the new fuel pressure regulator. GO TO ANOTHER DEALER to purchase a replacement filter/regulator. The regulators are made in batch lots. If one doesn't work for you, the rest of them from the same batch lot at the same dealer won't work either. A regulator purchased from another dealer will most likely come from a different batch lot that is hopefully more compatible with your bike.

  4. BMW's official fuel pressure specification for the F650 GS is 3.5 Bar +/- 0.20 Bar. They have legal reasons for specifying this. The fuel pressure requirement is unique for each bike and not exactly 3.5 Bar. The fuel pressure variance should not be more than +/- 0.10 Bar from whatever pressure each individual bike requires. For the more adventurous, it appears that the BMW OEM fuel filter/pressure regulator device can be replaced with off-the-shelf discrete components from the auto industry in the form of a fuel filter and an adjustable fuel pressure regulator to allow for precision fuel pressure tweaking. There is some question about the sustained accuracy of adjustable regulators, along with obvious warranty issues involved with the bike if make these modifications. It might be much simpler to purchase a third party fuel pressure regulator that comes with a third party bike attached to it. :-)

  5. If you are happy with the way your bike is running, inserting a third party in-line high pressure fuel filter between the fuel pump output and the OEM filter/regulator input would be a prudent thing to do in order to avoid having the replace the OEM device for fuel filtration reasons in the future. This is also the least intrusive modification that should also preserve your bike warranty. To restore the bike to factory condition, all you would have to do is replace a piece of fuel hose."

Additional Fuel Filters
by Harold

Q. Any feelings on whether BMW would use an additional fuel filter as a modification which would nullify your warranty?
A. The following describes installation on a fuel injected F650 GS:

The K&N Mini Billet Fuel Filter can be found at: http://www.knpowersports.com/docs/accessories.html.

My intent is to use the K&N as the primary fuel filter, to be installed in front of the F650 GS fuel pressure regulator input, duplicating the fuel flow plumbing found on my car. My car has over 150,000 km (93,000 miles) on it and has never had the fuel pressure regulator replaced on it - the item is not even on the regular maintenance schedule.

You MUST install it to operate in "by-pass" mode. In by-pass mode, if the filter becomes clogged and you don't clean it, it will let unfiltered fuel through to maintain fuel circulation. To cool the fuel pump, fuel is circulated at a rate of 2.5 liters per minute. This circulation must be maintained. For operation in by-pass mode, you install it so that fuel flows through it in a direction opposite to the arrow engraved on it. When installed in by-pass mode, you have to clean it often enough to prevent it from going into by-pass operation. If it goes into by-pass operation, then the BMW filter/regulator device begins to do the filtering.

If you install it in regular filtration mode ( fuel flows through it in the direction of the arrow engraved on it ) as the filter becomes more and more clogged, less and less fuel is allowed through it, and will cause the fuel pump to overheat due to a lack of fuel circulation. This WILL be a warranty issue.

The filter is installed by disconnecting the hose from the fuel pump output nipple and inserting one end of the filter into the hose. The other end of the filter is connected to the fuel pump output nipple using an 8 cm length of 8 mm inside diameter high pressure fuel injection hose rated at 100 psi. You will also need 3 fuel injection hose clamps.

Fitting of the (aftermarket) K&N Fuel Filter.
Q.
Can there be any pressure/volume problems with an extra filter in line?
A.

Pressure: Pressure is determined and maintained at 50 psi by the BMW filter/regulator device. The fuel pump is capable of developing pressures higher than that.

Volumetric Flow: You MUST use K&N #81-0312 Mini-Billet Fuel Filter, the one with the 5/16" I.D. barbed fittings. With the filter element removed, using a one foot column of water for gravity feed, the measured throughput is approximately 2.7 litres/minute. Using an identical setup for testing, the filter with the 1/4" I.D. barbed fittings only allowed 1.5 litres/minute of water to flow through.

The filter element has a surface area of 4 square inches and is not a limiting factor (when clean) in how much fuel is allowed through. The limiting factor is the inside diameter of the plumbing fittings.

The fuel flow rate is 2.5 litres/minute at 50 psi in the F650 GS fuel injection system. Under this kind of pressure, the K&N #81-0312 Mini-Billet is capable of handling much more than 2.7 litres/minute measured under gravity feed.

Mine is April 2000 build. It ran perfectly until they (BMW) replaced the filter/pressure regulator device. Then it took five more replacements over a period of seven weeks before they found one that my bike liked. I installed the K&N fuel filter immediately after that. As far as I'm concerned, any mechanic that puts his paws on that thing again, is going to be taking his life in his hands.

I cleaned the K&N filter element at 6000 km by soaking it for about 10 minutes in toluene, sold as "Toluol" in the paint department of your local hardware store. "A fast drying cleaner, degreaser, solvent for industrial paint applications."

During reassembly, care should be taken to insert the element the same way it was before cleaning so that the direction of fuel flow through the filter element remains the same as it was before cleaning. This way, if any trapped particles remain after cleaning, they won't be release into the fuel stream by reversing the direction of fuel flow through the element.

At 6000 km, the filter element appeared tarnished. The tarnish disappeared after dropping it into the "Toluol". I did not see any particulate matter floating around, even after I swished the element around a bit. The "Toluol" remained clear and colorless.

Aftermarket Fuel Filters
by Harold

Q. Does the K&N Mini Billet filter work for the fuel injected models too?
A. I have it installed on my fuel injected F650 GS Dakar.

Q. I didn't see any mention on that web page of fuel pressure specifications for the filter.
A. The filter exceeds all BMW specifications. For example, the filter can withstand a pressure of 6000 psi. The operating pressure in the BMW fuel injection system is 50 psi.