RIP workhorse/donkey

Discussion in 'The Garage' started by Grahf, Sep 8, 2019.

  1. Grahf

    Grahf "Special" tinkerer

    Joined:
    Nov 26, 2012
    Oddometer:
    60
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    Hi all,

    Friday morning i had my faithful duke 125 (2011, 25kmi) die on me on the way to work and i cannot figure out whats wrong. It happened a few weeks ago but after a short period on the roadside it fired up just like normal. Essentially the bike loses all power (not electrics) and starts to decelerate just like engine breaking until you come to a stop and rather than idle it just dies. This time it wouldn't restart.

    Has strong spark
    Fuel pump appears to be working
    Jets clear and has been cleaned
    Air filter is clear and has been cleaned
    No air leaks between intake and throttle body
    Valve springs all look good and the gaps are all in spec
    Cam chain timing is all lined up and looks good
    Piston rings are relatively new-ish and have been running fine

    It cranks but never starts although there is some blow back in the exhaust and intake which is why i checked the springs and timing.

    I get an blink code one long, nine short which is apparently "fuel pump lamp - circuit fault". The obd scanner returned a P1601 and P0650, i cleared them and they popped right back up next try.

    I’ve changed the relay with a known working one and no change, still not firing. I double checked the pump output and it’s definitely more than enough and I’ve changed the pipe just in case any kinks.

    I’m not very good with testing electrics. I usually just search for continuity between known points. All checked out.

    Any ideas?

    Thanks guys.
    #1
  2. ABHooligan

    ABHooligan The Flying Mythos

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    Is there a fuel filter in your tank somewhere? Is the fuel pump still producing good fuel pressure when the bike is dead? What do the two OBD codes point to?
    #2
  3. Grahf

    Grahf "Special" tinkerer

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    There are two filters, one internal that you cant change and one external that has been changed a few months back. I dont know what you mean about producing fuel pressure when the bike is dead, i turn it on, it primes and when i crank it pumps out petrol.

    I dont know what either code is. Online seems to offer random results. Nothing specific to KTM or my bike. Neither match the blink code.
    P1601 - either crank position sensor, MAP sensor, fuel temp sensor etc etc
    P0650 - MIL malfunction, communication malfunction etc

    Going to check compression as soon as i can.
    #3
  4. MJS

    MJS Long timer

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    Fuel pump volume may seem ok but it needs to have the correct pressure to push fuel through the injector. I have experienced this on a KTM that had good pump volume when the hose was free flow but wouldn't run because of a bad pump ( actually pressure regulator part of the pump assembly).
    #4
    Arbolmano and YesRush like this.
  5. Grahf

    Grahf "Special" tinkerer

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    Nov 26, 2012
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    Just ordered a fuel pressure gauge and an adaptor for the long compression adaptor for the ktm. Soon as they get here i'll start testing. I hope it isn't the fuel pump as that's an expensive replacement! The bike is 8 years old and has been used almost daily so i cant really complain!
    #5
  6. digger2

    digger2 A cad & a bounder

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    Suck, bang , blow. Not much too it. Air in, fuel and spark then it goes bang. At some point one of the three is missing
    #6
  7. shovelstrokeed

    shovelstrokeed Long timer

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    It is Suck, Squeeze, Bang, Blow, you maroon. Nothing happens without all four.
    #7
    digger2 likes this.
  8. south

    south Been here awhile

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    A spritz of starter fluid will tell you if fuel delivery is the problem.
    #8
  9. ABHooligan

    ABHooligan The Flying Mythos

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    I have seen fuel pumps produce adequate volume and pressure when cold, but after running for a while and getting hot, they aren't able to keep up. My question, reworded, is, "Does the pump still produce adequate pressure and volume after the bike breaks down?" Answer seems to be yes.

    I am leaning toward a fuel pressure/volume problem.
    #9
  10. Grahf

    Grahf "Special" tinkerer

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    Easy start/starter fluid did nothing. Not even a cough. :becca
    #10
  11. Grahf

    Grahf "Special" tinkerer

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    Adaptor part for the compression tester came this morning. 0 compression. Not even a flicker (kinda expected some movement tbh even if low). I'm going to have to take it apart again :bluduh
    #11
  12. broncobowsher

    broncobowsher Long timer

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    Leakdown (just dump compressed air down the spark plug hole at TDC compression stroke. It will be blowing out somewhere. Gives you a direction to look.

    My first thought is to look at the valves, any stuck open?
    #12
  13. Grahf

    Grahf "Special" tinkerer

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    I don’t have a leakdown tester. I could prob use part of the compression tester to do it but my air compressor isn’t working. Haven’t had the time on inclination to replace it.

    I’ll drop the engine tonight and have a look for the obvious. IIRC last time It was the exhaust valve springs that went so I’ll look there first.
    #13
  14. Grahf

    Grahf "Special" tinkerer

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    Hello Mr Zero Compression!

    A60C2D9E-C40A-44CC-8FE5-3C1B544E9B6E.jpeg

    Going to replace all valves and seals. Springs look in good shape. Going to soak this in some carb cleaner tonight.
    #14
    LuciferMutt likes this.
  15. YesRush

    YesRush Long timer

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    Now you can check what pressure you have now.And compare that # to bike if it doesn’t start sometime down the road.I too had a bad pressure regulator.
    If your in-tank pump is like my 14 500 xcw you can change fuel filter by disassemble it.
    CHeck to see if other parts like the crank is still in spec.
    #15
  16. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Yikes. What happened to the piece that came off? Any scoring or other marks on the cylinder wall?
    #16
  17. Grahf

    Grahf "Special" tinkerer

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    No idea, blown down the exhaust? no marks in the cylinder. The chips and scratches seen in the picture were there before. Nothing new. Piston doesn't actually look too bad.

    Hell of a lot of carbon build up in the exhaust outlet though.
    #17
  18. shovelstrokeed

    shovelstrokeed Long timer

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    Gonna be interesting regarding that valve seat. I would certainly consider a new one.
    #18
  19. Grahf

    Grahf "Special" tinkerer

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    Update:
    All parts replaced and its running fine now. As it was in pieces i took the opportunity to do a few small maintenance tasks on the engine and frame. Shims, chain, couple wiring things etc.

    Cheers for the help guys!
    #19
  20. Wentwest

    Wentwest How's that work?

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    That valve burned, I think. Maybe it was adjusted too tight and never closed fully long enough to drain off the heat.
    #20