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Thread: Fuel filter- plus or not?

  1. #1
    not so retired henzilla's Avatar
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    Sep 2006

    Fuel filter- plus or not?

    Not a particular model specific issue and it is about BMW's...

    A recent trip had me thinking about the reason or choices of using a fuel filter. We just returned from a multi-day trip to Taos/Santa Fe, NM in between weather systems...kinda. It started a bit pun intended.

    There was a recent thread in Hex/Camheads about adding a fuel filter to a 2011 Camhead RT. This was running thru my head about 120 miles into the trip.

    The bikes we started on were Helen's '02 1150R at 108K, and my '09 GSA with 86K. Her's is on the third filter and she's had this bike for all but 2000 miles...roughly 24K on each filter, some in a few years, others a bit longer. My GSA was new in late '08. One FPC and third fuel strip.

    We made a 100 mile fuel run after leaving at chilly sunrise and stopped to top off with coffee & gas before making a run towards the Panhandle. We typically go 200+ between stops due to her tanks size. Our typical re-fuel is me closest to pump, but she fuels first so she can roll off first to park if we are stopping for a stretch.

    I didn't notice the fuel tanker alongside the Top Tier station until Helen had fueled and I was midway when H pointed to it lurking out of my direct view. I typically do not stop when I SEE one with hoses in place. Helen got about 4.5 gallons, me about 2 as we had not left with full tanks...well I did. Those who know H know this story!

    We headed out and within 20 miles of the refuel, H hit the talk button to let me know her bike was misfiring. I thought fuel related after worrying about that tanker, yet my bike kept running fine at that point. After she said it wasn't any better after maybe 5 more miles, we pulled over for me to look it over. All connections to the injectors looked OK and no visible signs of anything major. It just would not idle, but would run OK at higher RPM as I ran it up and down the shoulder of the highway.

    A few years ago, one of the spark plug leads failed in the rain, shorting very clearly in the spark plug recess. They are fairly new. It ran differently than that this time, so I don't think ignition. The HES is relatively new and I had not done any major work in the last 2000 miles. Even leaving the throttle advance on wouldn?t help it stay running.

    We were 25 miles away from a town w/ any facilities and 125 from home...H said she was OK trying to make it back home or as far as the bike would allow. Me going to get the truck/trailer with back-up bike was option 2 and she wasn?t waving that flag yet.
    Luckily only four small towns traffic to deal with as she had to really keep the rev's high when stopped and it died a few times...never got out of 5th either as she said it started lugging and mis-firing. We stopped in LLano about midway home to add some HEET to the remainder of fuel and the last run to the house. It was the first town with an Auto Parts store.

    My bike skipped a few times, but I was ultra-sensitive to any sketchy behavior...even caught myself keeping MY rev's high when stopping! Laughed at that more than once. I was sending positive throttle rolls her way I guess. It was gusty so some of that may have been me skipping.

    Upon arrival home I noticed the right side had been extremely hot as the Jet-Hot coating on the headers had peeled at the flange...yikes! Maybe the isopropyl was a bit high! I added enough for 3-4 gallons, but she was burning a lot of fuel at 75MPH(legal) in 5th as she ran out 5 miles from home...luckily I had a fuel bottle I keep for her & Chuck and we rolled home. Swapped over to her 12R and left the 1150 in the corner until we returned. I haven't touched it yet.

    So, if the fuel was the causal factor, was the amount I got insignificant with a 9 gallon tank and she got almost a full tank, or did the R12's system let it pass on thru. Or did she get the brunt of the crud by going first?

    AND...if I had her filter where it should have been by now ,could I have just drained the fuel and popped on a new filter and kept going? If we were not close as we were to home and not had bike options, I would have had to tackle it anyways.

    As a point of reference, the R with it's steel tank, and the scarce ST were the only R1200's with a OEM filter mounted outboard the tank.The other models do not have a filter at all. My 09GSA and our R12S do not have one, nor do our K12S?s. My RT also was filter-less. We both are close to 200K on several late model Beemers with no fuel issues...other than strips and a FPC. oh, and a few fuel run-outs on 1100/1150's

    Helen's R1150R still has the internal's move to the outside on my list but not high up there. It might have made a diff to this tale.

    Our bikes are 50/50 on filters...other than her R12R and her ?07 Thumper GS, none of our post 2005 bikes have a filter I have added them to the 70's Airheads since both had iffy tank linings. You know we get moisture laden fuel on occasion, are the newer bikes able to digest it better w/out the filter?

    T-shooting after I added the HEET will not help me in regards to moisture contamination, hopefully the injector pattern test will help decide if the filter is somewhat plugged. This time I will move it?I guess.

    Steve Henson
    SABMWRA MOA Club#62's Flat Fixer/ current forum moderator
    It's not the breaths you take, but the moments that take your breath away-D.Dillon/G. Strait

  2. #2
    Registered User dieselyoda's Avatar
    Join Date
    Mar 2013
    Winnipeg, MB, Canada

    This thread is interesting.

    This thread should bring a wide variety of comments and opinions.

    In my experience, diesels, filters are an absolute necessity. A very small amount of water through an injector tip can cause catastrophic engine failure. I've done enough rebuilds to say that can I make that statement with certainty.

    But a gasser with fuel injection? The pumps pump the crap to the filter so they can handle it. The injectors are relatively robust. They can take some water and small bits plus they have filters for the big bits built in.

    I would think the screens inside an injector are there to protect the needle and seat from being plugged with big crap but I bet they could shoot little crap into the cylinder where it's burnt off and out the exhaust it goes. If that screen gets plugged, a good #10 screw removes the filter and a strong thumb pushes them back in. Most fuel injection places give you a dozen injector screens for free. They buy 1000 at a time.

    I have never given the filter pro/con on a gasser a thought before. I think I will now.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case, my baby, fast, fun)
    3xR90/6, two just sold, one for a sidecar. 1983 K100RS (Cafe now)
    Very Rough R80RT. 1987 K1100RS (freaking hooped I think)

  3. #3
    MOA #24991 Pauls1150's Avatar
    Join Date
    Apr 2008
    south of Los Angeles


    Several months ago, I changed out the external AUTOMOTIVE fuel filter (WIX p/n 33032) that I have on my 1150. Just for jollies, I turned it upside down over a piece of white paper and blew thru it in the reverse direction. The stuff that came out was mostly liquid, but all of it was brown...
    This filter rests horizontally, so I hope that it can trap water too.

    Just a few months ago, I got a chunk of debris in my tank while filling up - I think some low-life scum-sucking dirtbag of dubious ancestry stuck this piece of hard plastic up inside the accordion smog booty that we contend with here. The only way to find out what it was & remove it was to disassemble the pump/float assembly from the tank (turning the tank upside down did not dislodge it). The filter on the intake side of the pump was less than 10,000 miles old, but it was stained brown throughout also.

  4. #4
    Registered User
    Join Date
    Sep 2008
    Wilmington, NC
    I've only managed to clog one filter (on a cage) over 40 years ago and it was one of those super dinky ones on a 240Z that everyone replaced with a std American one with about 20X the area,

    Symptoms of a plugged filter show up not as misses but as failure to accelerate well or failure to be able to maintain speed due to lower fuel flow rate. Takes a lot to plug an FI bike so bad it won't idle. Anything that's intermittent about the behavior suggest another cause.

    If intermittent type behaviors, I would first suspect that separated water/ethanol is the culprit if its not electrical which is as likely. Many stations sell low amounts of premium and I've got friends who've run into this problem at such places. The fact that a tanker is stirring it up makes this possible.

    High EGTs from lean EtOH mix could fry HES wiring especially if not teflon..

    Does the 1150 have those amusing U shaped hoses in the tank that are known to split or blow off?

    Many modern stations use filters in delivery- makes it tough to get dirt through.

    On fuel critical machines I've owned (eg boats for fishing well offshore) I followed some simple rules to avoid troubles. Separators and filters as a must- big ones clearly visible and accessible. If multiple tanks, never fuel both tanks from same source and be certain tanks can be switched if machine is built without that capability. Make sure there is always enough fuel on board that the lowest power motor can get you back in (even if it takes a lot longer due to sea conditions.)

    Ain't it great to have spare bikes? (Got a K1200GT I don't trust as far as I can throw it - it doesn't get selected for long trips)
    Last edited by racer7; 11-12-2013 at 06:02 PM.

  5. #5
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Albuquerque, NM
    Surely somewhere there's a technical paper describing how/why some current FI systems can be designed without fuel filtration and I think it would be VERY interesting to understand this. Over the years of German gasoline fuel injection systems, there have been some pretty big filters, some with maybe a liter capacity. VW's usually on a budget and featured some small ones and of course they're smaller on motorcycles-- just change them more often. Yes, it's almost always a proactive change and likely unnecessary.

    It's going to get interesting I guess when direct injection makes it to motorcycles if it ever does. The principles for this and the equipment is a lot like modern diesels, and the one I have uses piezoelectric injectors that fire 5 times per power stroke and pressures are in excess of 20,000 psi. There's a frequently changed (20k miles) filter there for sure. The system is typically German (although significant components are Delphi) and connections use uniform torque clamps, in this case CLIC clamps, and service literature insists they be replaced and never reused and no other type clamp be used. I'm fairly new to BMW bikes with FI and haven't done a filter change yet, but for sure won't use anything but the OE Oetiker clamps, as it's obvious I've not a chance of duplicating the specified tightness with a screw clamp (nor with "generic" hose).
    Kent Christensen
    '12 R1200RT, '02 R1100S, '84 R80G/S

  6. #6
    not so retired henzilla's Avatar
    Join Date
    Sep 2006
    C'mon Kent, thought you would have that info

    I have had two Cummins Diesels and am a filter nut on those. I have changed some pretty nasty filters. My daughter had a Chevy Cavalier years ago that wouldn't run past idle...filter alongside frame rail luckily and had water in it.

    When I regularly bought fuel near the Gulf Coast I always had some water come out of the manual filter drain at fill-ups. So many sea level towns have been flooded, even with heavy rains at some point and how sealed were their tank access points?

    When you see a diesel pump with the nastiest filter cartridge hanging off of it, even at a top-tier locale, you have to wonder IF it's ever changed unless the State AG guys are inspecting the facility. Lot's of pumps and few inspectors I assume.

    I had a filter on the /6 I recently brought back to petcocks and 0 flow. New filter(s) had it flowing well and bike ran fine. It wouldn't accelerate prior though the filters ''looked" OK.

    I still haven't looked at her 1150 yet to see what's what. I use both the crimp and FI rated screw clamps. Depends on where they are located(inside vs. outside tank.
    And racer...that pesky u-shaped hose is about two years old (who knows shelf life age) and crimped on. The bike would not accelerate well in 1st, ran fine at higher RPM. The HES is fairly new as well.
    Steve Henson
    SABMWRA MOA Club#62's Flat Fixer/ current forum moderator
    It's not the breaths you take, but the moments that take your breath away-D.Dillon/G. Strait

  7. #7
    Registered User ratze's Avatar
    Join Date
    Feb 2013
    Good read indeed,,,
    The pursuit of reality at all cost.

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