FJ 1100 runs on 2 cilinders

[gijs]

Hello everyone,

I've got a 1984 FJ 1100.
The problem is that it only runs on 2 cylinders most of the time, sometimes it runs on 4 cylinders for a minute but then it goes back to 2.
I thought is was the coil and replaced it. That makes no different at all.
I put an Ohmmeter over the wires and they were all good.

now question is : Could it be the ignition box or the switch by the crankshaft?
I don't know that much about motorcycles but I hope someone has had the same problem and knows what wrong.

[Harvy]

Those are both possibilities mate.....and another is spark plugs...have they been replaced?
Because its a lost spark system, if one plug goes bad, its mate may not fire either.


Harvy

[fj11.5]

Have you tried swapping the coils and leads over 1&4 into 2&3 and swap the orange to gray plug over as well, , do u know what 2 cylinders dont fire ?

[andyb]

First off:  Which two cylinders?  If it's the left pair or right pair, it's not an ignition problem (probably), but more likely a fueling problem.  If it's the inside pair or outside pair, then spark sounds quite likely.

Second off:  New plugs in it, ya?  A bad plug that shorts (low resistance path to ground) will prevent the related cylinder from firing (i.e., a bad plug on #2 would take #3 with it, v/v for 1 and 4).

Next off:  Check for an intermittent short or open circuit on the low voltage side of the coils.  You'll have to trace the wiring out and look for frayed or broken bits between there and the ignition unit.  Kinda a hassle, that.

To check for a bad coil, swap the two that are on there (both the low voltage side and the sparkplug side) and see if that moves the dead cylinders.  If it does, then yeah, you're almost certainly got it sussed.

[gijs]

Thanks for the reactions
I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3,
i have tried an other coil and that doesn't help.
i have tried an other ignition box an that doesn't help either.
i have also checked the resistance of the pickups and that is good to.

Now I will check the wiring from the coils to see if there is a short to the ground

[gijs]

I have put a new piece of wire between the coil and the ignition box and that makes no difference.
Now I really have no idea what to check for.

[Flying Scotsman]

Thanks for the reactions
I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3,
i have tried an other coil and that doesn't help.
i have tried an other ignition box an that doesn't help either.
i have also checked the resistance of the pickups and that is good to.

Now I will check the wiring from the coils to see if there is a short to the ground

I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3
i have tried an other coil and that doesn't help.

Has to be coil or conection/wiring.One of them is not firing.

Moving coil to other cylinders shows you the good coil.You might have a bad other coil.(the one you swapped)
You can test the coils it sounds like you have a bad coil or coil conection.

[gijs]

Thanks for the reactions
I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3,
i have tried an other coil and that doesn't help.
i have tried an other ignition box an that doesn't help either.
i have also checked the resistance of the pickups and that is good to.

Now I will check the wiring from the coils to see if there is a short to the ground

I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3
i have tried an other coil and that doesn't help.

Has to be coil or conection/wiring.One of them is not firing.

Moving coil to other cylinders shows you the good coil.You might have a bad other coil.(the one you swapped)
You can test the coils it sounds like you have a bad coil or coil conection.

If I put the wire from the right coil on the left coil then the other coil works. so it can not be a bad coil.
and the orange wire that comes out of the ignitionbox, I have cut that and put a new wire to the coil and that doesn't work. ( I don't know if it should work this way)

[SkyFive]

I'm making the assumption that this problem just began  and that it didn't occurr after another repair.

I would check the wiring from the pickups to the ignition module; open wire, pinched wire at the oil filter housing, alternator or pickup cover. I have to tell you, when I was installing my engine I removed the wiring connectors from the plug that go to the igniton module to route them thru a tight spot, when I reinstalled them I had two of the three wires backwards and I had the same symptoms that you have.

[gijs]

can anyone tell me if the plug from the ignition with 4 pins if it has to have 3 or 4 wires in it

[fj11.5]

Should have 3 wires . black orange and gray , would be for the coil pick ups ,

[gijs]

does anyone have a wiring diagram so that I could rewire the intire wiring from the pickups to the coils.
just to make sure that's not the problem.

[Pat Conlon]

does anyone have a wiring diagram.....

I can show where to get one.
On the back page of all the FJ owner's manuals, is the wiring diagram for that specific model....Don't have a owners manual?
Down load one free from Yamaha:  http://www.fjowners.com/index.php?topic=3483.0

I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3,
i have tried an other coil and that doesn't help.

If it sparks on 1&4 and you swapped coils and now it sparks on 2&3, then you have a bad coil.  Something must be wrong with your replacement coil.

Why do you think that it is the wiring when the circuit for coils 1&4 and then the circuit for coils 2&3 work correctly when the right coil is used?

Cheers!   Pat

[gijs]

does anyone have a wiring diagram.....

I can show where to get one.
On the back page of all the FJ owner's manuals, is the wiring diagram for that specific model....Don't have a owners manual?
Down load one free from Yamaha:  http://www.fjowners.com/index.php?topic=3483.0

I have swapped the 2 coils and then I get a spark on cylinder 1 and 4, and otherwise it sparks on 2 and 3,
i have tried an other coil and that doesn't help.

If it sparks on 1&4 and you swapped coils and now it sparks on 2&3, then you have a bad coil.  Something must be wrong with your replacement coil.

Why do you think that it is the wiring when the circuit for coils 1&4 and then the circuit for coils 2&3 work correctly when the right coil is used?

Cheers!   Pat

I mend that i swapped the connectors

[andyb]

Well, that means that the dead coil is still there.

Spec them both out, but it sure sounds like one of them is bad internally.  As the stickers say, no user serviceable parts inside, but this time they mean it.