No spark, 1991 TRX 300 FOURTRAX 2WD - ATV Enthusiast Community

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Old 04-06-2011, 12:01 PM
Weekend Warrior
Join Date: Apr 2011
Posts: 3
Default No spark, 1991 TRX 300 FOURTRAX 2WD

Hello and thanks in advance for any help or resolutions,
I have a 1991 Honda fourtrax TRX300 2WD that was running fine until a couple of weekends ago. The battery has always seemed to hold a good 12.+ charge, I dont know how many amps it is putting off though.
I took the spark plug out to see if it fired/sparked. Nothing visible. But with the key on I could hear a faint ringing sound like when a TV is on but no picture just the black screen. The noise is coming from the larger of the two boxes under the front fender, the ICM/"CDI", ignition control module. when I turned the key off the noise stopped, until I turned the key back on and tried to start again, the noise returned. I then noticed when i touched the spark plug, in the plug wire still, to the engine some very small blue sparking occurred from the plug threads to the engine,none in the plug gap. would stop again with the key off. I measured the voltage coming from the plug wire itself when I kick start, it would jump up to around 6-7 volts then back down to almost nothing. I have cleaned about 5 plastic plug connections and the battery and solenoid terminals, with no resolve. A couple of funny things that happed while I was riding it the day before it died was that it simply went dead like you turned the key off while riding, not like it wasn't getting enough gas. It just went dead. I kick started it within one kick and it fired right up. Of course I would have these problems the day after I put a new brake cable on, new rear brakes, oil change, oil filter and air filter. But I don't believe this is the cause because it ran fine after doing all of these things. I Put in another CDI box that was supposed to be good. still no help. Now no current or voltage at all through the plug wires. But higher voltage from the CDI box through the wires that connect to the coil.

I replaced coil with a new one still no spark or voltage at plug wire, but there is still voltage through the wire that feeds the coil voltage. I have gotten the quad to start once but when it is killed no restart. What is happening? I have used the honda service manual and tried to test all the electrical as directed. the coil checks out OK, so does everything else seem to as well. But the little black diode has no "0" as indicated in the manual as it is supposed to have continuity, I jumped with a wire between the female connectors that the diode connects to. still no spark. but if the diode is bad would I still be getting voltage through coil supply wires? As I test the voltage between the green negative (black multimeter probe) and the Black and white wire Positive with the (red multimeter probe) I get a negative voltage like - 16.78 volts then it continues to drop as I let off the starter button. Is this correct? I have the batery positive and negative cables on correctly and the voltage at the battery is not inverterted as mentioned above at the coil feed wires. I keep the battery on a charger. Also would a bad battery stop the firing process cold even on a kick start attempt? If the diode was bad would i still get voltage at the coil supply wires?
Also I tested the pulse generator coil wire harnass and I checks out at the 348 or so Ohms as indicated in manual, but the manual doesnt specify where exactly to test it on which side of the connector, at the wires that go into the crankcase cover or on the other side going to rectifier? I get nothing going into crankcase wires and the 348 ohms on the other half of the connector going to the rectifier. Any suggestions?
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Old 04-06-2011, 12:22 PM
Pro Rider
Join Date: Aug 2008
Posts: 1,317

Have you replaced the plug?
"If you think health care is expensive now, just wait until you see how expensive it is when it's free."
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Old 04-06-2011, 12:47 PM
Weekend Warrior
Join Date: Apr 2011
Posts: 3

yes new champion plug .035 gap, and trie old NGK plug still no spark. Nor any voltage through plug wire itself. New coil and new wire.
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Old 04-09-2011, 09:52 PM
Pro Rider
Join Date: Jun 2010
Location: Notheast Alabama
Posts: 1,264

Did you read the lenar diode both direction with meter? if good the diode should read ohms in one direction and infitnity the other way if good. also did you check the voltage reg,/recfi? and yes got the have good hot batt.for the ignition to work correc.
[LEFT]2-Trx300fw,Trx450 foreman,Mod.Lt80's,Kfx80's,Vtx1800c,350rancher es, 660 rhino.LOVE ENGINE SINCE 1970.
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Old 04-11-2011, 08:27 AM
Weekend Warrior
Join Date: Apr 2011
Posts: 3
Default Neutral switch

thanks! I think the neutral switch is the problem now, it failed the continuity test. the manual said it must have continuity. I assume with the switch on. The wierd thing is that the neutral light works like it is supposed to "on" in neutral and "off " when in gear. However no continuity. I tried to bypass the switch by unplugging the wire at the switch and grounding it to the frame and leaving the wire unplugged and the switch. This still did not help. Everything else has seemed to pass the tests. Maybe one day I can figure it out. Thanks again
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Old 05-05-2011, 12:16 PM
Weekend Warrior
Join Date: May 2011
Posts: 1
Default interrmittent spark

i believe my issue is nearly the same as you mritech. where is the neutral switch? what does it look like?
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1991, 300, 300ohms, atv, bypass, cdi, coil, foreman, fourtrax, honda, neutral, plughonda, plugs, small, spark, trax, trx, wire

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