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950 Solid State Fuel Pump Diy

Discussion in 'Dakar champion (950/990)' started by Andy dawg, Dec 12, 2008.

  1. Andy dawg

    Andy dawg aka Andy 950

    Joined:
    Jan 8, 2008
    Oddometer:
    42
    Location:
    Melkbos CT, WC, RSA
    The Mitsubishi fuel pump is a known weakness on and otherwise FANTASTIC machine. The points burn away due to arcing.
    1st the 2c bush repair. Glue a piece of placstic between the rubber buffer and the "top" of the point, as pointed to here with the soldering iron. This should get you home (I did 6000km on such a jimmey)
    [​IMG]
    The next bit is a R 6.00 fix for a R 2 000.00 job. (That is about $0.60 against $200.00) It is a variation of ridewestKTM's post which I found on http://www.ktm950.info/how/fuel_pump/mitsubishi/rideswestktm_mitsubishi.html

    I take no credit for it nor can I guarantee anything, I have done 3 pumps so far, and am currently riding with one on my bike and at the price it is definately worth it!!!
    I also made some spelling mistakes on the photos and called the 15 k ohm resistor a 15 ohm resistor, that will have to stay as it is otherwise I will never post this.
    Here is a photo of the stock pump showing the basics
    [​IMG]
    You need to get an FET (or MOSFET) IRFZ44; a 15 k ohm resistor and a 1 M ohm resistor. I got mine from Mantech, but any electronics shop will have these.
    This diagram should help a bit as the photos are not very clear
    [​IMG]
    Bend the legs of the FET as shown
    [​IMG]
    Solder the 1M to the Gate and Source legs. You need to fit an M3x25 bolt with 3 washers to the hole in the FET as you will use the bolt to fasten the FET to the pump cover. I drilled a 1.5mm hole through the bolt and used dental floss to help guide the bolt through the hole.
    [​IMG]
    Next up, unsolder the coil wire and unscrew the Negative (the brown wire).
    [​IMG]
    I didn't have any lugs, so I cut the lug off the negative wire and soldered on end of the 15 k ohm resistor to it.
    [​IMG]
    Now solder the Gate and 1M pin to the mounting where the coil wire was removed.
    The coil wire gets soldered to the Drain pin of the FET, the photo was taken after I had already shrunk on some heat shrink.
    I found the better way of joining the 15k ohm resistor to the + was to cut the positive. In fact I also cut the plug off and removed the protective sleeve so I could clean it and you need bare wire to test the pump. Solder the resistor to the + and insulate with heat shrink. Take note to solder in such a way that the wires will easily reach the opening in the cover (cap)
    [​IMG]
    When you're done it should look something like this.
    [​IMG]
    You need to estimate the position of the M3 bolt and drill a hole through the cap where the bolt goes through. Now use the dental floss to guide the bolt while pulling the wires through the rubber grommit in the cap. I fitted the grommit first and then fed the wires through, that is another reason why it is better to cut the plug off and solder them back afterwards.
    I then used a 12V car battery charger to test the conversion, VOILA!!!
    Seal the bolt and grommit with some silicone
    [​IMG]
    #1
  2. Head2Wind

    Head2Wind MotorcycleMayhem

    Joined:
    Mar 13, 2006
    Oddometer:
    2,712
    Location:
    NorthWet Washington
    Excellent write up!

    I did a conversion on mine too...... seems that cooling needs to be a consideration. My modified unit failed in Moab miles from much of anything. I was carrying my spare thankfully.

    I just opened it up last night to figure out what happened. to my surprise it got hot enough to unsolder one of the resistors from the PCB..... um, ya. :eek1

    I like your approach where the FET is handling the high current switching which is still driven by the pump stroke/points.:deal rather than continuously pulse energizing the pump independent of if it needs to or not.

    That mount stud could have a heat sink bolted to it to help cool the FET quite easily. slather a little heat conducting paste on both sides of the cover, bolt the two together and wa-la...
    #2
  3. Andy dawg

    Andy dawg aka Andy 950

    Joined:
    Jan 8, 2008
    Oddometer:
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    Tx H2W, would the heatsink be outside then? In that case, all the heat would have te be conducted through the M3 bolt.

    It may be worthwhile twisting the wires and pins where practical for added reliability
    #3
  4. Head2Wind

    Head2Wind MotorcycleMayhem

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    Mar 13, 2006
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    Location:
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    yes, the m3 would be the direct metal path. not sure how good of a heat conductor the plastic is. it would help to have conductive paste. I use the stuff on computer RAM and CPU heat sinks.... Zinc Chromate? cant remember off hand
    #4
  5. ridewestKTM

    ridewestKTM Long timer

    Joined:
    Jun 7, 2007
    Oddometer:
    1,873
    Location:
    Mesquite NV
    My solidstate kit doesn't use the points. The FET mod does. The fet mod will not get any hotter than stock. The solid state kit will get as hot as stock one will at full power even if you are going slow. While I have had no problems on my adventure with the solid state kit - the SE and SM may not be as good of candidates for the SS kit. It should work though.

    The FET mod should go on good points - Are you trying them on burt points??? Let us know how that works.

    H2W if there is a failure on soldering - my apoligies. And if there is a temp problem let's discuss, but the temperature can't be high enough to melt solder or the IC would fail first.
    #5
  6. Andy dawg

    Andy dawg aka Andy 950

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    Good point...points....no pun intended:D No really, I mean, 3 of the pumps I've done so far are on bad points with the spacer jimmey already done. IE foooked points. Doing VERY well so far.

    Me no electronics expert, just blindly followed your post (albeit with difficulty :D ) but I understand the concept of less current through the points so I thought jimmeyed points should be OK
    #6
  7. ridewestKTM

    ridewestKTM Long timer

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    Cool !- I'm not surprised, but I not sure I would have tried it. Should go a long time anyway.

    BTW: Someone tried epoxying the FET on the point bridge. It's a good idea to make things fit and easy, but I think if the FET make electrical contact it will stop working. ???
    #7
  8. gefr

    gefr Life is a trip

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    Location:
    East Med, Greece
    Never installed it, but it works. I believe the temp problem rises when the bridge between G and S is not used. Then the FET gets very hot. This bridge is used to discharge the FET which behaves as a capacitor.

    H2W, did you use this discharging resistor (1M Ohm)?

    You could mount the FET, with glue on the bridge, on its back. No conductivity with the points' bridge. Thus you avoid all the drilling part.

    Sealing will have to be applied to the cap-pump body surface.
    #8
  9. Head2Wind

    Head2Wind MotorcycleMayhem

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    I have to look. not sure.
    #9
  10. ridewestKTM

    ridewestKTM Long timer

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    The FETS I have been using are metal backed and that metal is connected to the D lead. So if attached to the point bridge and my method of using the body as + (resistor + to body) then the pump will go full on. The epoxy may insulate.

    The FET efficiency is a function of the gate voltage - you can check my math but the current to the gate is so low we should get near full voltage to the gate when points close. Sooo - the FET should not get hot.

    The whole circuit on the solid-state (my IC circuit) stays cool - the pump is what gets warm.
    #10
  11. gefr

    gefr Life is a trip

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    I glue it face down, so the plastic surface is touching the bridge, so no contact with the D. Cheers.
    #11
  12. HappyGoLucky

    HappyGoLucky Goeie Grys Giftige Gert!

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    Good job Andy! :clap

    Looks like you'll be doing mine when I am back in RZA....:evil
    #12
  13. Andy dawg

    Andy dawg aka Andy 950

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    Anytime dood, very impressed with the mod so far, went through about 1/2m of water yesterday and did 600 odd km no probs so far.
    Proof in the pudding:evil

    PS just the noisy cam chains worrying me now, but that's on another thread.

    F... I love this bike!!!!!!!!!
    #13
  14. Andy dawg

    Andy dawg aka Andy 950

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    RW, I've done more than 1000km inc water crossings, dirt, even a few small jumps on this mod with used points. No problems so far, I'll keep giving feedback. I commute 70km round trip daily so I should be a good Guinnee pig:evil
    #14
  15. Andy dawg

    Andy dawg aka Andy 950

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    ridewest, do you have any info/instructions on the "full" solid state conversion? I just followed your FET mod blindly, but have no knowledge of electronics
    #15
  16. ridewestKTM

    ridewestKTM Long timer

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    I designed and had made circuit boards. I sell these as a kit. Check vendors section for details. (search KTM 950 solid state fuel pump)

    I could tell you the circuit but assembly is an issue and make it useable
    #16
  17. Professor Badass

    Professor Badass ROTC Special Forces

    Joined:
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    Here are some pictures with the mosfet glued (jb quik weld) face down to the points bridge. After these were taken, I locked everything together with clear epoxy. It's back together and running great. The green wire is negative in this case. (not brown).

    Anyway, it is possible, everything fits and it works so far. I'll report back with any updates or failures.


    [​IMG]

    [​IMG]

    [​IMG]
    #17
  18. Professor Badass

    Professor Badass ROTC Special Forces

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    Wires before:
    [​IMG]

    Wires after:
    [​IMG]
    #18
  19. ridewestKTM

    ridewestKTM Long timer

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    I sell a kit - it's on a printed circuit board so DIY is not as easy.

    PM me if you want to discuss.

    My own has two full seasons and 10K miles - not a glitch.
    #19
  20. Professor Badass

    Professor Badass ROTC Special Forces

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    I've ridden 700 miles since adding the mosfet to my pump. No problems so far. :clap
    #20