1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

93 Xj600 Suddenly no longer wants to start.

Discussion in 'XJ Technical Chat' started by jasperwasthere, Jul 19, 2022.

  1. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Bought the bike non-running. Had a stripped starter idler gear, split the case replaced all that and threw it back together and it started right away no hesitation. And continued to start that way for a while. Now suddenly one day it does not want to start at all. It will crank over fine, and occasionally fire a few times or let out a really loud backfire out the exhaust. I fell it may be having an issue getting fuel. I have a clear filter in-line and can tell it doesn't really fill with fuel. But if I unhook the line from the gas tank gas will flow fast and freely out the petcock.
     
  2. faffi

    faffi Active Member

    Messages:
    103
    Likes Received:
    53
    Trophy Points:
    28
    Location:
    Norway
    I would begin by verifying that you have spark. Best way is with a spark tester pen (you just hold it up against the HT lead when cranking) or a strobe timing light, as both ways will only flicker if you have a spark inside the engine - it is quite possible to have a spark in free air that cannot jump under compression. But if you lack instruments, check that you have a bright blue spark jumping across a spark plug gap at least.

    If you have spark, and losing compression on all 4 cylinders at once is very unlikely without you having noticed a racket, fuel is your most likely culprit. It could be as simple as stale gas - in the heat, it can get stale in a few days - and draining the two outer floats and let them refill should see the engine fire. Set the fuel tap to PRI for filling them. Also, by draining the floats - petcock NOT set to PRI - you will know if there is sufficient fuel in them.

    Also worth thinking about; when fuel level in the tank is low, a fuel filter can stop flowing when facing the pressure coming from the float chambers, even if fuel flows when the hose is disconnected. Been there, done that.
     
  3. Dan Gardner

    Dan Gardner Well-Known Member Premium Member

    Messages:
    775
    Likes Received:
    344
    Trophy Points:
    63
    Location:
    Minneapolis, MN
    I too am a proud member of the elite club named “Spent Several Hours Troubleshooting a No Start Only to Realize You’re Out of Gas”
     
  4. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Plenty of fresh gas, I know that much. That was my first guess :/

    also I’ve seen the PRIME petcock setting mentioned on other forums, mine doesn’t have that. Just ON OFF and RES.

    I will do a spark check
     
  5. Franz

    Franz Well-Known Member

    Messages:
    3,176
    Likes Received:
    923
    Trophy Points:
    113
    Location:
    Scotland UK.
    Use a multimeter across your battery terminals too. Make sure you have at least 10 volts when starter motor is cranking the engine. Less than ten volts can mean the transistors don't work in the TCI. You can also try bump starting the bike in gear. That way the transmission is turning the crank leaving most of the electrical energy for the ignition system as it's not operating the starter motor.
     
    k-moe and faffi like this.
  6. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

    Messages:
    19,377
    Likes Received:
    6,545
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    +1
    Battery.
    Charge it, load test it, and check the alternator brushes for wear.
     
  7. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Battery fully charged, over 10 volts at cranking. Spark is intermittent. (Tested by grounding to the head my test light doesn’t fit the plugs) When it does, it’s a good healthy looking bright spark. It just sparks one time seemingly at random.

    Also Is it normal that the plug would discharge moments after cranking when coming in contact with the engine? I’ve done many spark tests and never experienced this. After testing I went to grab my wrench to put the plug back, when I picked up the plug (still in the wire) and got near the motor it zapped me and the bike kind of fired once without cranking.
     
  8. short_circutz

    short_circutz Member

    Messages:
    82
    Likes Received:
    30
    Trophy Points:
    18
    Location:
    Sault Ste Maire, On, Canada
    When there is a voltage across the primary of the ignition coil, if the power is removed from it (like when hitting the kill switch, or turning then ign off) the magnetic field in the coil collapses and will cause a high voltage pulse across the secondary, thus creating a spark.
     
    Franz likes this.
  9. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Further update, coils test okay. Primary and secondary windings check out.

    what’s next? Also worth noting: ‘93 so there is no clutch safety switch and the kickstand switch is bypassed (the two wires for its harness are jumped together.
     
  10. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Ok, another update folks. Decided to get back to looking at this again.

    There is spark now, it's a healthy looking blue. I still have no start. I tried draining the bowls for some fresh gas. It just turns over and puffs some smoke out the exhaust. Even tried seeing if would at least fire once with a sprtiz of starter fluid and still nothing. Now further confused.
     
  11. Bryce W

    Bryce W New Member

    Messages:
    24
    Likes Received:
    3
    Trophy Points:
    3
    Location:
    Virginia
    Its odd that it was running and then quit, so most likely not something like bad compression, as that wouldn't just "go bad". If you sprayed starter fluid and it didnt pop off also most likely not fuel starvation related. It could be that instead of running without fuel, you have too much fuel. You didnt accidentally push the choke lever all the way on? Similarly, id check and make sure no furry friends made a home in your intake/exhaust system. Apart from fuel, check your sparkplug wires. Make sure you have them in the correct order, you hear of people switching it up accidentally....
     
  12. Franz

    Franz Well-Known Member

    Messages:
    3,176
    Likes Received:
    923
    Trophy Points:
    113
    Location:
    Scotland UK.
    If you have a colourtune (not for tuning in this case) you can check if you have a spark during the compression stroke. A spark with the plug removed does not automatically mean you have a spark under compression as the starter is taking some of the electrical power. Have you tried roll starting it?
     
  13. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    Well they do have numbered tags on them but in fairness I didn't number them. 1-4 is on the left coil (if sat on the bike) and 2-3 on the right. Does it matter within the same coil which is which? I had read before some people saying it didn't.


    I do not have colourtune unfortunately. Any simple way to check that/timing otherwise? I failed at roll starting before but only because my entire area and driveway is just dirt and gravel so the bike fails to get traction and just slides. Maybe tomorrow I'll walk it down to the road and try.
     
  14. Franz

    Franz Well-Known Member

    Messages:
    3,176
    Likes Received:
    923
    Trophy Points:
    113
    Location:
    Scotland UK.
    You can use a car battery and jump leads to check if it will start.
     
  15. Timbox

    Timbox Well-Known Member

    Messages:
    2,055
    Likes Received:
    611
    Trophy Points:
    113
    Location:
    Wisconsin, Tomah
    +1 for to make sure you have a good battery.

    The issue is you are getting spark and then a back fire. So too much fuel in the system? Removed the plugs clean them. If you have compressed air, shoot some air down each spark plug hole to more or less dry out all the excess gas in there. Put the plugs back in and give it a try....no choke....

    Have you checked to see if the gas is making its way to the oil? A lot of these bikes have a issue with their fuel cut off petcock. If you are having too much fuel issues it might be making its way to your oil area. Take a look at the oil window and see if you can see any air in the window, if not, take the cap off the oil fill and see if you can smell gas.

    Let us know how it goes.
     
    Franz likes this.
  16. Simmy

    Simmy Well-Known Member

    Messages:
    2,023
    Likes Received:
    929
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    What you read is correct. The XJ ignition system is known as "wasted spark", both plugs on that coil fire together, one is fired for the power stroke, the other is wasted, firing again for the spent chamber.
     
  17. jasperwasthere

    jasperwasthere New Member

    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    United States
    The battery checks out okay. Ill give this stuff a go. The petcock and pump are both new and the bike was running previous with these new ones.
     
  18. Bryce W

    Bryce W New Member

    Messages:
    24
    Likes Received:
    3
    Trophy Points:
    3
    Location:
    Virginia
    Remember if the bike is cranking over, you only need compression, fuel, and spark. If you have the ability, a compression test is worthwhile to eliminate it as an issue now, and just to have as knowledge as the owner of the bike. Give us some more information on your "spritz of starter fluid". How much are you spraying, and into where. If its fuel related, which if you read the threads will realize that's the major thing with these bikes, then eliminating that prematurely leads to a lot of head aches (ask me how I know). Give it a healthy amount of starter fluid right into the airbox no filter while cranking, A few seconds and then keep cranking, see what happens. Don't crank too long, don't want to abuse that new starter gear :).
     
  19. bensalf

    bensalf Well-Known Member

    Messages:
    1,152
    Likes Received:
    220
    Trophy Points:
    63
    Location:
    yorkshire ,england
    i agree with the above , except , its a 93 xj600 it wont have any alternator brushes
     

Share This Page