yes, another fuel pump question

Discussion in 'GS Boxers' started by 1100cruiser, Sep 29, 2012.

  1. 1100cruiser

    1100cruiser n00b

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    so the bike, 1994 r1100gs. Been sitting for 2 years and now trying to get her running again. Engine cranks, getting spark, but no fuel. Not too sure on what wires feed power to the pump, but when i test the 4 wire harness, 1 wire has power. Now when I re-connect the harness, i lose the power all together. Could the fuel pump be shorting out and cutting the relay? Definitly at a loss right now :huh
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  2. mouthfulloflake

    mouthfulloflake Not afraid

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    the fuel tank electrical connector has 4 wires, the outer 2 I believe are the power for the fuel pump

    if you look close they are the larger ( thicker) wires.

    the smaller two wires are for the fuel level display.

    be careful if you power it up though, a spark might be bad!
    #2
  3. 1100cruiser

    1100cruiser n00b

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    is it the brown and gree wires (on the pump side of the harness)? I tried powering it up, wire was getting warm, but no go.
    #3
  4. 1100cruiser

    1100cruiser n00b

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    just looked at it again, there are the four wires on the pump wiring, whit,green,brown, yellow. all four are the same size. on the bike side harness, 1 big brown wire, green/white, yellow/red, and white/blue.
    #4
  5. mouthfulloflake

    mouthfulloflake Not afraid

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    its the outside 2 wires, brown is ground, and I think the other is white with blue tracer.
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  6. MsLizVt

    MsLizVt pfft ...

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    1100Cruiser, Mouthoflake too, hi!

    Because of the year, 1994, you may want to check the ground wire. If you have a plastic tank, and even if you don't have a plastic tank, there was a difference in the way the plastic and steel tanks were grounded. The plastic tanks, have a big thick brown wire that has a connector half way between the tank and the bike. I've had issues with that connector, where the ground wire was loose inside the connector.

    Interestingly, on my bike, the dealers a long time ago swapped the plastic tank out, but did not change the wiring. Why would they, ya know?

    None the less, if you're using a test light to see if you get power to the pump, but still the pump isn't running, check the ground.

    Of course, this is just my opinion, and your bike might be totally different, but it's a suggestion.

    Let us know, please, how you make out.

    Enjoy,



    Liz
    #6
  7. slartidbartfast

    slartidbartfast Life is for good friends and great adventures Supporter

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    Bike sitting for 2 years eh. Was there fuel in the tank? Did you clean it out or just add more? My guess would be a seized fuel pump. Do you hear a whine for a second when you turn the power on? Does the RID come on - showing fuel level and oil temp? If the answer to both these questions is yes, then a hose inside the tank could be split or plugged. You will need to take the tank apart either way. Look in the Hall of Wisdom for instructions and , if necessary, information on a cheaper than OEM fuel pump replacement.

    Whether that's it or not, it's probably worth buying a can of DeoxIT and some dielectric grease. Clean and grease the fuel pump connector. Pull, clean and grease all the relays and fuses (the fuel pump relay and fuse for sure).
    #7
  8. 1100cruiser

    1100cruiser n00b

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    I haven't heard the pump come on at all. I have tried to put direct voltage to the pump and no go. The oil light and low fuel light do come on and I do have a click from the mototronic relay when raising/lowering sidestand. It is the plastic tank. So of to a new pump it is....
    #8
  9. 1100cruiser

    1100cruiser n00b

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    Oh, and I did the direct power straight to the 4 pin connector on the pump sid eof the harness
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  10. vintagerider

    vintagerider Long timer

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    edit: Just dug up a '93-'94 ver. pump plate. All four wires to the harness plug are the same light gauge, 3 of which which pass through a single small 3 terminal electrical bulkhead fitting (as opposed to dual b-h fittings 95 and up). Unique to this style also is a welded grounding tang on the outside of the bulkhead fitting. So a single small b-h serves both the pump batt pos (but not pump ground) and the fuel gauge. Later style moves the pump power off this small b-h fitting and passes pump ground also through b-h rather than relying solely on p. plate for pump ground.

    1) GREEN- pump pos terminal 2) Yellow-float board 3) White- float board. On the inside of the early style the pump's only ground is to a machine screw to which the fuel level slidre contact is also grounded via a connection to the hair wire between slider and board.

    Therefore, as described by Liz, a separate pump ground brown wire p/n 2306543 with eyelet must be fitted under one of the tank mounting bolts (nut/stud if metal tank). A quick disconnect is fitted to connect to the chassis ground and to allow tank removal w/o undoing the pump plate bolt to release the ground wire ring terminal. Link to part and diagram (listed for early RS):
    http://www.bmwmcchattanooga.com/showAssembly.aspx?ukey_assembly=193255

    >> The pump ground may become compromised by i) bad connection to the the internal ground screw. ii) broken or corroded tang on the outside of the b-h fitting. iii) loss of grounding of the pump plate via 2306543 brown quick disconnecting grounding wire. Of these three the last is by far the most likely.

    >> Later style pump plate should retro fine and the pump will operate w/o 2306543 attached however the early style does have the advantage of being more leak resistant. Use of a more efficient pump with lower current draw is preferred on these.

    As mentioned, the revised p plate have a second larger bulkhead dedicated to pump power via heavy gauge wire. If using the older style then particular attention must be paid to maintaining the grounding circuit and keeping all components in top condition to prevent under-fueling.

    One advantage to the early style is that the larger dedicated pump blk-hd IS absent. This larger blk hd fitting is secured to the pump plate from the inside with a crimp ring and an o-ring seal which is not visible or serviceable. This o-ring may crack or the pressure seal lost from expansion over time resulting in a slow drip of fuel on telelever, the source of which is often difficult to diagnose unless you know what to look for. Diagnosis of the problem is made by filling the tank with two gallons and letting it set on the pp side for several hours. Fuel appearing on the pp which is not from the big o-ring is coming from the pump pwr blk hd..

    /!\ always disconnect the pump plate harness before lifting the tank. It is not uncommon for the metal tank to ground out against the batt + post and fry the pump plate. For extra safety the battery ground wire should also be disconnected.
    -------

    It's what Liz said. Better title for this thread: "Early style 11xx pump plate" The '93-'94 had the early style pump plate. Upgraded in '95-'96. Identified by one electrical bulkhead. Not sufficient power capacity on those thin wires for the oem style pump. There should be a separate ground wire (brown) with a connector. Pull the pump plate. Time to refresh internal fat hoses anyway. Pump with have a date code. Probably marginal and should be replaced. Pop off the suction screen, rotate impellers, looked for broken ones, check bearings. In a pinch, clean/reassemble might restore svc temporarily but risk of engine damage from too lean (low pressure). Read crackhead's pump thread. The 69222 Bosch requires less current.

    Heavy green: pump battery pos

    Heavy brown: pump ground, pump motor grounded to pump plate also.
    #10
  11. MsLizVt

    MsLizVt pfft ...

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    Vintagerider, et al, hi!

    We agree, based on the age of the bike, and that it most likely had the plastic tank, there should be that big thick brown wire that comes off the bulkhead, and goes to the negative side of the battery (to the best of my recollection). There is an inline connector in that thick brown wire. The wire ends in the connector loosen up, and the connector isn't making good contact.

    How do I know this, you ask? The bike died on Interstate 80, just coming into Indiana, from Illinois, at one in the morning. After pushing the 700 pound bike on the slight uphill for what seemed like miles, I found a lighted place I could take the bike apart. Long story short, when I fiddled with that connector the pump worked and bike started up. I jury rigged the connector and that kept the bike running fine.

    A couple of years later, when I was swapping pumps, I found out the ground inside the tank, goes to the bulkhead, which is where the big brown wire goes to on the outside. If that big brown wire isn't grounding to the battery, the pump isn't going to run. At least that's my opinion. The metal tank bikes all have a different ground, I believe.

    Again, this is just my own experience.


    Liz
    #11
  12. MsLizVt

    MsLizVt pfft ...

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    Sorry, in my previous comment, I mentioned that it probably had been a plastic tank. Just reread this, to find that it is a plastic tank.
    #12
  13. 1100cruiser

    1100cruiser n00b

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    well, I finally found the problem......the fuel pump had corroded so bad that it was frozen. installed a new pump and now re-installing the tank to run it:clap Thanks for all the input!
    #13