Running on one cylinder

Discussion in 'Engine, Fuel and Exhaust' started by Rabid Ranger, Jul 21, 2011.

  1. Rabid Ranger

    Rabid Ranger Member

    68
    18
    1
    Went for a short ride, running great, 04' FatBoy FI......stop for about one hour....start it and running on front only. Shut down restart and same. Get tool kit out and check plugs...ok. switch plugs...still only front cyl. Check spark good spark....crank it with wires off...check plugs.....front wet, rear dry.....looks like clogged FI.....or no signal to rear injector from ECM....what do you think...any suggestions?

    Did I miss something?
     
  2. RibEye

    RibEye Junior Member Contributor

    973
    48
    44
    Wire harness to rear injector? Sometimes wire breaks, leaving insulation intact. Fire it up and wiggle injector wires. Might find that rear cylinder might come back, or come and go.

    Easy enough to beep out (with an ohm meter), once you gain access to injector wires, and ECM plug. Note: one wire to each injector does not come from ECM, but from 12V supply. You will need a schematic for your scoot.

    Enjoy,
    Rich P
     
  3. Rabid Ranger

    Rabid Ranger Member

    68
    18
    1
    Thanks Rich....did the wiggle but no change...not much room w/o removing the tank.....checked the DTC and no faults show....have not got the meter out yet and i do have the diagram for the injector wiring.

    RR

    Well i will continue tomorrow am....and yes Rich it appears that one wire is 12vdc supplied to both injectors from the fuel pump fuse. so a ground must be sent from the ECM to fire the injector....but access to the connector on the injector is well....

    RR
     
    Last edited by a moderator: Jul 21, 2011
  4. RibEye

    RibEye Junior Member Contributor

    973
    48
    44
    Sorry. Tank off time. Strange that it does not throw a code.

    If I may suggest: HARLEY TANK 5/16 FUEL LINE CROSSOVER QUICK DISCONNECT

    [​IMG]

    I installed these quick disconnects last time I drained and removed my tank. Now I can remove a full tank in 10 minutes...No longer an issue. They pop apart and seal.

    Provided by Herko, a trusted vendor on this site.

    Enjoy,
    Rich P
     
  5. Rabid Ranger

    Rabid Ranger Member

    68
    18
    1
    Thanks again Rich.....there appears to be 2 DTC codes for each injector one for open/low EFI and one for high EFI so to my thinking if the wire from the injector to the ECM was open it would throw a code? But if the injector was clogged then it would not. Make any sense to you? My concern is that I may have gotten some dirty gas dumb (EDIT) me went and got some premium at a station that was fined for selling bad gas......my bad. So do you or anyone have any ideas about how to clear the injector?

    Will look into the quick disconnect. Geeze my old sportster was a easy to work on deal.....

    Thanks aganin for the responses

    RR

    [note]
    A Friendly Reminder - Harley Davidson Community
    [/note]
     
    Last edited by a moderator: Jul 21, 2011
  6. RibEye

    RibEye Junior Member Contributor

    973
    48
    44
    Injectors are pretty robust. Filtering is pretty complete. Possible, but slim, unless the bike has been allowed to varnish. Varnish flakes from lines and pressure regulator can clog things up. Prior to pressure regulator is the fuel filter. It should clog long before something from it back could get through to the injectors, unless ithas been damaged some way.

    It is possible to remove the injectors, without removing the throttle-body...tough but doable. You might try swapping injectors, and see if the problem moves.

    My money is on wires. Do you have a TFI, or other fuel tuner installed? I think it is possible that, if you have a TFI, it might hinder code throwing, if the wire break is downstream from the TFI (between TFI and injectors).

    Enjoy,
    Rich P
     
  7. Rabid Ranger

    Rabid Ranger Member

    68
    18
    1
    I suspected that it would run on both cyl when cold....well it is so with this new inf any other suggestions?
     
  8. Hoople

    Hoople Account Removed

    7,198
    0
    34
    Just wondering,,What means are you using to say it's the rear cylinder not firing vs the front. (touch, exhaust pipe etc)

    What engine/performance mods have been made to the bike? (Power commander, ignition system, spark plug wires etc)

    As far as DTC codes... You see the word "None" from all family groups.?
     
  9. Rabid Ranger

    Rabid Ranger Member

    68
    18
    1
    Hoople its a stock bike exhaust heat and removing the rear plug wire makes no change and when cranked w/o plugs in the front cyl is wet and the rear dry. Spark is good. So I am about to take it for a short ride and see if it "happens" gonna put some new gas in it the gas in it now is "suspect" since I normally do not use the station where I got the current gas since it has in the past had "Bad" gas.

    So here goes..

    RR
     
  10. Hoople

    Hoople Account Removed

    7,198
    0
    34
    I doubt it is the gas. And if it was, your not going to unclog the injector by refilling the tank with good fuel. You say it is always the rear cylinder. No DTC codes. If the ground shot coming from the ECM is good, and the injector pigtail is good, I would throw a couple of injectors at it. They are not crazy expensive.