HELP 03 ex250 left cylinder not firing

[MistahT]

My friend rides a 2003 pregen we built for him. We got it cheap, got it running, and did a mild street fighter since the fairings were toast. It's been running well until a couple weeks ago when one cylinder stopped sparking while on the highway and he had to limp home on one cylinder. The bike has a vapor gauge which uses a wire wrapped around the spark plug wire to read rpm, in this case it happens to be the same cylinder (left side when sitting on the bike). At the same time the bike started running poorly the tach stopped reading signal, and to confirm there wasn't a problem with the vapor as well we switched the wire to the other spark wire and fired the bike. Sure enough there was a tach reading which leads us to believe there is an issue somewhere along the ignition system that is only affecting the left cylinder.

We swapped the plug, wire, coil, and even igniter (ecu?) from my wife's 2004 ninja which runs to no avail, and the parts taken off the non running 03 worked fine on the 04. That leaves us stuck as to what the issue could be... Any help would be much appreciated, especially since we can test any ideas from here pretty easily with the running bike.

[MistahT]

Any ideas at all you guys?? Toss em out there! What's in line before the coil in the electrical system?

[The_big_dill]

Do you mean you added your own electrical part to the system?

If so, i would remove it all together, i have heard people having headaches with their vehicles, and it was all because of their electrical "additions".

Take the plug out and while in the boot and against a piece of metal, check if there is spark, this is a sort of sanity check.

[FvnnyL3tt3r1ng]

I'm guessing the 04 parts didn't work on the 03?

[MistahT]

Originally Posted by The_big_dill

Do you mean you added your own electrical part to the system?

If so, i would remove it all together, i have heard people having headaches with their vehicles, and it was all because of their electrical "additions".

Take the plug out and while in the boot and against a piece of metal, check if there is spark, this is a sort of sanity check.

We checked for spark before, after, and during swapping the 2004 Ninja parts. We tried plugs, wire, and coil, as well as what we believe to be the ecu. And yes, we grounded the plug to the frame (actually tried a few different places just to be sure) to see if we were getting spark or not.

The Vapor gauge isn't an "add on" really, it replaces the gauges. Actually, all we really have hooked up from the harness is 12v power. It's grounded to the frame, runs a signal directly from the temp sensor, and runs a single wire to a magnet on the front brakes for speed. I don't think it's connected anywhere else into the electrical system of the bike.

[The_big_dill]

Originally Posted by MistahT

We checked for spark before, after, and during swapping the 2004 Ninja parts. We tried plugs, wire, and coil, as well as what we believe to be the ecu. And yes, we grounded the plug to the frame (actually tried a few different places just to be sure) to see if we were getting spark or not.

The Vapor gauge isn't an "add on" really, it replaces the gauges. Actually, all we really have hooked up from the harness is 12v power. It's grounded to the frame, runs a signal directly from the temp sensor, and runs a single wire to a magnet on the front brakes for speed. I don't think it's connected anywhere else into the electrical system of the bike.

Well from what i know, these engines run wasted spark. So my next guess is to check continuity in the wire that delivers the signal to the igniter.

[MistahT]

Originally Posted by The_big_dill

Well from what i know, these engines run wasted spark. So my next guess is to check continuity in the wire that delivers the signal to the igniter.

My friend and I are mechanically inclined, but electrically idiots. Can you take a picture or something and show us the line you're talking about?

[Rollingmenace]

Ok here goes start by single component does the plug spark on the case just by itsself... I'd check to see if the coil is grounded

[MistahT]

Originally Posted by Rollingmenace

Ok here goes start by single component does the plug spark on the case just by itsself... I'd check to see if the coil is grounded

The one side does not spark. Even swapping plugs, wires, and coil from the other bike it does not spark.

[The_big_dill]

Look at a wiring diagram, available here:

http://faq.ninja250.org/images/a/a7/..._Schematic.pdf

You need to use a continuity tester (most, but not all, Multimeters have this feature) and see if it beeps positive when you touch both ends of the wire.

Basically you are checking if there is a copper conductor all the way through that wire, if the wire is broken somewhere along that path, this test will fail.

[land sea air]

Thanks for all the replies guys, I'm the owner (kinda) of the bike and actually made the original post in Mistah T's garage, figured I'd join up to make things easier for him. I'll try out some of these suggestions this weekend once I have some time.

Just to clarify some info:

the vapor only reads spark passively through the sparkplug wire so we haven't added anything to the ignition system.

the coil is connected by two wires at the front of the bike and both seem fine, I will check continuity on them when I get some time.

the parts swapped in from the running 04 bike to the non-running 03 did not change anything but the parts from the 03 still allowed the 04 to run fine.

the plug does not spark when held to the case, but the same plug sparks fine when connected to the other cylinder.

Let me know if there are any other questions about what is happening and I will update soon!

[cuong-nutz]

Stupid phone. That's a really weird case. Bad ignitor?

[land sea air]

going by the service manual the ignitor is the ecu looking box on the rear left side of the bike with two plugs, when we swapped this box from a working bike mine still did not work.

[cuong-nutz]

Originally Posted by land sea air

going by the service manual the ignitor is the ecu looking box on the rear left side of the bike with two plugs, when we swapped this box from a working bike mine still did not work.

So does your CDI BOX/igniter work on the other bike? Trying to rule stuff out. And you are sure the ignition coil works too?

Definite need a multimeter to do some testing. Make sure your ground wire from your battery for the harness isn't disconnected.

[Lychee]

Based on what you have told us (parts from your broken bike work on your working bike) it sounds like the fault is either the CDI ignitor box, or the wiring loom between the ignitor and the not working cylinder. The CDI cannot be tested, but the wiring loom can. I am also leaning toward the wiring since your bike has been modified. Since the other cylinder is firing and both coils are on the same power circuit, that problem is in the ground circuit. Perform a continuity test between the following wires:

5plug ignitor connector - Black to
Coil1 - Black

5plug ignitor connector - Green to
Coil2 - Green

You only need to test the one that doesn't work, but the schematic does not describe which coil is on the left side, so go by the color of the wire other than the red one.

If it passes that test (continuity indicated), also check that the black wire that normally goes to the tachometer is adequately insulated from the frame and not providing a short to Coil1. To do this, unplug BOTH the CDI and Coil 1 and test for continuity between either

Coil1 - Black to
Frame or battery negative

OR

5 plug CDI/Ignitor - Black to
Frame or batter negative

If the test also passes (no continuity or infinity resistance), then swap the CDI from the 2004 and see if that works.

Also, is the inductive tachometer getting power from an extra wire you connected directly from the battery or have you spliced it into an existing power line? If you have spliced it in, what color is the wire?

[land sea air]

The Ignitor worked fine when connected to the working bike as did the coil, the inductive tach is grounded to the horn is wrapped around the spark plug wire for signal, other than that we have not added to or altered the electrical system. Sounds like the issue might be the wiring which I will test asap.

[alex.s]

Originally Posted by MistahT

The one side does not spark. Even swapping plugs, wires, and coil from the other bike it does not spark.

heres how the electrical system works:


the crank position sensor sends a signal to the ignitor, the ignitor waits a specific amount of time, and then cuts signal to the coils. this causes the field built by the coils to collapse into the spark plugs.

we can rule some things out since you tried swapping with known working parts... rule out ignitor, plugs, coils, coil wires. we know you are getting good crank signal since one coil is firing. this leaves only a single component that could be responsible.

the wiring between the ignitor and the coil that isn't firing.

[alex.s]

with your multimeter, turn the bike to the on position (not started) and check the power going to the coils. they should both read good voltage. if one doesn't, there is your problem. if they both read good, try cranking it. do both the coils show fluctuation on the input power? no? if they don't, maybe there is a short that is keeping the coil always powered.

[land sea air]

Sorry for the delay getting back in here, turns out the majority opinion was right and one of the wires from the ignitor was routed badly near the front of the bike and had partially frayed, easy fix and the bike is back to normal. Thanks for the help!

[The_big_dill]

Originally Posted by land sea air

Sorry for the delay getting back in here, turns out the majority opinion was right and one of the wires from the ignitor was routed badly near the front of the bike and had partially frayed, easy fix and the bike is back to normal. Thanks for the help!

Thanks for the feedback, glad you managed to fix the issue.