Another Bayou with no spark!!! Thrown so many new parts at it.....

[Filthy_Mule777]

 I'm currently pulling my hair out over a customers 98  bayou 2x4 KLF300b. I've changed every electrical component on it twice and in a couple instances three times. Still no spark, I am baffled. Initially customer brought it to me complaining of a hard start no start situation and in fact, it wouldn't start. I changed the starter relay, spark plug,  CDI box, and starter circuit relay after which it fired right up ran very well but then started having issues with the neutral switch/light where it wouldn't come on and wouldn't allow it start or even turn over. I found in the wiring harness a loose connection, I got it taken care of and secured and that solved the problem. So now that it would crank up again and run fine I called the customer over to test it out see what he thought as I've never heard it run before and I wanted to get his opinion on how it was running. Customer ride it around a little bit pulled it back on my carport and turned the key off and said it was great, and had never ran better or started so easily, then we set up a time for him to come pick it up the following day and he left. Well where he pulled it on my carport and shut it off was in the middle of the carport so I jumped back on it to park it off to the side,  crank it up no problems put it in reverse went about maybe 18 inches and it stalled and ever since that point it has not had spark or run. I replaced the CDI box again with a better brand, I replaced the ignition coil twice put another starter relay on it and I've also changed out the stater and the pick up coil (pick up coil twice) and I'm just I'm lost I don't know what else to do to it. I've had this customers  four wheeler for four months now whereas he's a patient guy I need to get it out of here so I can move on to something else. I've seen dozens of threads across  different sites for off-road, 4 wheelers, ATVs, UTV's, whatever and they are all experiencing the same sort of issue but they never ever post hear the problem was or  the fix. So I'm hoping somebody here has a little bit of knowledge on this particular issue sent since it seems to be so widespread.  Thanks in advance for any help or suggestions.

[Mech]

Well given it\s so intermittent I'd be suspecting a wiring problem. I'd be checking for good power supply to the ignition unit and the coil, and that they both had good earths.

Since it got turned off and started again until you started to move it, I'd assume a wire just needs to move very slightly to loose power. Up around the steering head where the wires move a lot is a place they chafe through the insulation, and the other place where wires nearly always break is right at the end where they go into their metal terminal. They often break inside the insulation, and a bit of a wriggle sometimes makes they contact again, or, you feel the wire bends too easily because it's only the plastic holding it together. 

[kp3004x4]

Had similar problem with 2000 prairie found out was a wire problem it was both wires coming from engine for the neutral reverse switches guess that after vibration and such small wires just didn't hold up ,to fix problem I made up new wires from both switches all the way back to fuse solved problem.chk with volt meter to c if your voltage is up to pare while wiggling the wires.if not full 12.60 ish then your wires are faulty.

[Filthy_Mule777]

10 hours ago, Mech said:

Well given it\s so intermittent I'd be suspecting a wiring problem. I'd be checking for good power supply to the ignition unit and the coil, and that they both had good earths.

Since it got turned off and started again until you started to move it, I'd assume a wire just needs to move very slightly to loose power. Up around the steering head where the wires move a lot is a place they chafe through the insulation, and the other place where wires nearly always break is right at the end where they go into their metal terminal. They often break inside the insulation, and a bit of a wriggle sometimes makes they contact again, or, you feel the wire bends too easily because it's only the plastic holding it together. 

Thank you for the response and the suggestion but I have thought of that and where as that was exactly the issue the first time it died out and the neutral light wouldn't come on (it was even in the one specific place you mentioned, right underneath the handle bars where all the connections are). It would seem that I've been able to follow continuity from battery to key and all points in between! There where a couple wires that felt "floppy" near their barrel connector terminations that I cut back and butt spliced. I did run a couple of the tests you had suggested in another post and the only mentionable thing was while doing the earth tests with one lead on the negative battery terminal and the other to the engine ground when engaging the starter I picked up a very low voltage but a voltage none the less and it only appeared when the system was under load. Not sure what that means exactly but I'm certain it is significant somehow. I am also curious about another thing that I was leaning towards before the fore mentioned testing. I am wondering how in gods name do you check/adjust the pick up coil gap in this thing, I kinda feel like that is a very likely suspect considering it is the beginning of the signal and the voltage that will (on someone's somewhere) eventually be the spark that ignites the world. I've heard that 0.02 is the proper gap and that at 0.04 it will cease to make that spark at all, but the small inspection/timing port on the top of the cover isn't positioned right to be able to get a feeler gage, or anything really, in between the coil and the fly wheel. Any suggestions or thoughts on this?
 

[Mech]

Well first off, when you were checking the earths and saw a small voltage, how much voltage was it ? If it was a half a volt it's too much really. You need to find the bad earth connection. With a bad earth it's possible that when you spin the engine over by hand you might see a spark at the plug, and if you spin it over with the starter and the plug out the earth might be god enough to allow cranking and a small spark, but when the plug's in, and the starter's working hard, that bad earth could be enough to prevent the coil working properly.

The air gap is preset and isn't likely to be your problem. All you need to check is that the trigger/pulse coil has the correct resistance, and that it puts out a small voltage when the engine is spinning over. It probably only puts out about one volt, and it only does it once per revolution and it's very brief. Most digital gauges won't pick that brief voltage up. It's best to use an old fashioned analogue gauge with a needle. You will see the needle jump. It won't be readable but as long as it jumps then you know the magnet or trigger plate on the rotor is attached and doing it's job. Even when the trigger coil has the right resistance, and should work fine, they won't do anything if the trigger plate has fallen off the rotor, or if there is a flake of rust or a small collection of metal dust accumulated on the trigger coil's core. A single flake of rust, if it bridges the gap between the core and the rotor is enough to short out the magnetic field and prevent the trigger from happening. You need to check the trigger coils resistance to be sure it doesn't have a break or short, and you also need to test it's putting out some small amount of voltage to be sure there's nothing mechanical, like a flake of rust, stopping it working.

 

Edited March 28 by Mech

[kp3004x4]

I would definitely have to agree with mech on his comment even small amounts of rust will hinder voltage or contaminated oil residue.

[Pod]

On 3/27/2023 at 2:06 PM, Filthy_Mule777 said:

 I'm currently pulling my hair out over a customers 98  bayou 2x4 KLF300b. I've changed every electrical component on it twice and in a couple instances three times. Still no spark, I am baffled. Initially customer brought it to me complaining of a hard start no start situation and in fact, it wouldn't start. I changed the starter relay, spark plug,  CDI box, and starter circuit relay after which it fired right up ran very well but then started having issues with the neutral switch/light where it wouldn't come on and wouldn't allow it start or even turn over. I found in the wiring harness a loose connection, I got it taken care of and secured and that solved the problem. So now that it would crank up again and run fine I called the customer over to test it out see what he thought as I've never heard it run before and I wanted to get his opinion on how it was running. Customer ride it around a little bit pulled it back on my carport and turned the key off and said it was great, and had never ran better or started so easily, then we set up a time for him to come pick it up the following day and he left. Well where he pulled it on my carport and shut it off was in the middle of the carport so I jumped back on it to park it off to the side,  crank it up no problems put it in reverse went about maybe 18 inches and it stalled and ever since that point it has not had spark or run. I replaced the CDI box again with a better brand, I replaced the ignition coil twice put another starter relay on it and I've also changed out the stater and the pick up coil (pick up coil twice) and I'm just I'm lost I don't know what else to do to it. I've had this customers  four wheeler for four months now whereas he's a patient guy I need to get it out of here so I can move on to something else. I've seen dozens of threads across  different sites for off-road, 4 wheelers, ATVs, UTV's, whatever and they are all experiencing the same sort of issue but they never ever post hear the problem was or  the fix. So I'm hoping somebody here has a little bit of knowledge on this particular issue sent since it seems to be so widespread.  Thanks in advance for any help or suggestions.

I Have similar problem, let me know if you find anything...thanks

[Filthy_Mule777]

Will do, I'm pretty optimistic about the help and people on this site, that have been nice enough to offer suggestions and technical info. There seems to be a wealth of knowledge here and I'm sure with their help I'll find and fix the "gremlin" in my system. But I will be sure to post both cause and solution. Good luck on yours.

[Filthy_Mule777]

On 3/28/2023 at 3:41 PM, Mech said:

Well first off, when you were checking the earths and saw a small voltage, how much voltage was it ? If it was a half a volt it's too much really. You need to find the bad earth connection. With a bad earth it's possible that when you spin the engine over by hand you might see a spark at the plug, and if you spin it over with the starter and the plug out the earth might be god enough to allow cranking and a small spark, but when the plug's in, and the starter's working hard, that bad earth could be enough to prevent the coil working properly.

The air gap is preset and isn't likely to be your problem. All you need to check is that the trigger/pulse coil has the correct resistance, and that it puts out a small voltage when the engine is spinning over. It probably only puts out about one volt, and it only does it once per revolution and it's very brief. Most digital gauges won't pick that brief voltage up. It's best to use an old fashioned analogue gauge with a needle. You will see the needle jump. It won't be readable but as long as it jumps then you know the magnet or trigger plate on the rotor is attached and doing it's job. Even when the trigger coil has the right resistance, and should work fine, they won't do anything if the trigger plate has fallen off the rotor, or if there is a flake of rust or a small collection of metal dust accumulated on the trigger coil's core. A single flake of rust, if it bridges the gap between the core and the rotor is enough to short out the magnetic field and prevent the trigger from happening. You need to check the trigger coils resistance to be sure it doesn't have a break or short, and you also need to test it's putting out some small amount of voltage to be sure there's nothing mechanical, like a flake of rust, stopping it working.

 

So the pickup coil is new, I replaced it because the wires on the original had been cut through the insulation and one had several mills of copper cut through as well, so as a matter of preventive maintenance I ordered a new one and swapped it, I do still have the original and have removed the bad section on both wires and butt spliced them back and have also reinstalled it and tried at one point, I got no change so I put the new pick up coil back on & I'm pretty sure I did both resistance and high voltage tests and it passed both. I am a little confused (or would like some clarification to be sure I'm understanding correctly) a lot your description of the pick up coil function.  You said "if the trigger plate has fallen off the rotor or a spec of rust or collection of metal dust builds up these may not allow it to fire" (sorry I paraphrased) please clarify what you are calling the "trigger plate" and the "rotor", I'm assuming by rotor your talking about the large shiny circle that is connected to the crank shaft and has the raised rectangular piece of metal that passes closely to the pick up coil and signals it to fire, is that (the raised rectangle) what your referring to as the trigger plate, or are you taking about the small bracket that attaches with the pick up coil and is sandwiched between it and the mounts on the housing?  If I was able to actually see or download the repair manual that you guys offer in your library here I wouldn't be asking such basic questions, but I want to make sure our nomenclature is the same.