No Spark on rear cylinder
Seasoned HDF Member
Joined: Dec 2005
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From: poway
Are you sure that you are not getting spark, and it isn't a fuel problem? If you are sure that it is a spark issue then swap the plug wires around, and see if the rear will fire, and the front will not. Could be that the new coil is bad as well. The correct OEM part number is 31639-95 , which is a dual fired coil.
What I suggest doing on any M&M bike problems is to first make sure that the battery is in proper working order. Next check for any stored trouble codes. There is a key ON/Off procedure which will make the engine light flash the stored codes.
Do that after you have fun with Mickey & friends, and report back what you find.
What I suggest doing on any M&M bike problems is to first make sure that the battery is in proper working order. Next check for any stored trouble codes. There is a key ON/Off procedure which will make the engine light flash the stored codes.
Do that after you have fun with Mickey & friends, and report back what you find.
I would check the primary wires with a test light while cranking. Check both front and rear. You should be both sides stay on but go out periodically.
Stellar HDF Member
Joined: Jan 2009
Posts: 2,578
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From: On a Lake, not far from the Gulf
You sure you are getting fuel? Is the rear plug wet? Look under the nosecone, and see if there is any brown goo dripping from there. This is usually a symptom of a failing cam position sensor. Check the connector located under the right side of the lower frame by the rear brake line to ensure that one has not come out of place, or they are corroded/ dirty. Behind the right side cover by the ECM is the crank position sensor connector. It is barrel shaped. Take it apart, inspect the pins are making good contact, clean it up, and reconnect it. You may also want to check for an intake leak. Do you have the service manual for the bike? If you do there are flowcharts in there to help diagnose problems.
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Joined: Jul 2018
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From: Ireland
i tested them them with a volt meter and the front had 12 v for couple seconds when turned on and the rear had almost no volts ?
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,863
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From: poway
If the rear primary wire is low most of the time, you need to look for a short to ground in the primary wire or possibly a bad ECU. Make sure power going to the coil is good. Primary windings should typically sit at battery voltage except for short periods before spark is generated.
I would check primary resistance on both coils. Front and rear should be close. If both are off chance are that the coils were damaged by the short.
Grand HDF Member
Joined: May 2014
Posts: 3,822
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From: florida
how many primary terminals are on your coil?
2 or 3
if you only have 2 you have a dual fire coil, if so, one will get 12 volts at key/ign on, take a test light, hook it up to the POSITIVE + battery terminal, touch it to ground an make sure that it lights, after that touch it to the other coil primary terminal(not the one with 12 volts at key on). then crank the bike, while holding the test light on that termianl it should flash, this will tell you that you are getting the trigger from the module.
if your coil has 3 or more terminals on it, it is single fire, the same test applies, just that you touch the test light to the 2 TWO triggers, one for front and one for rear, if you get the trigger signal one one, but no spark, it's a bad coil, if you dont get the trigger signal its a bad wire, connection, or module issue.
post up a picture of your coil!!!
m
2 or 3
if you only have 2 you have a dual fire coil, if so, one will get 12 volts at key/ign on, take a test light, hook it up to the POSITIVE + battery terminal, touch it to ground an make sure that it lights, after that touch it to the other coil primary terminal(not the one with 12 volts at key on). then crank the bike, while holding the test light on that termianl it should flash, this will tell you that you are getting the trigger from the module.
if your coil has 3 or more terminals on it, it is single fire, the same test applies, just that you touch the test light to the 2 TWO triggers, one for front and one for rear, if you get the trigger signal one one, but no spark, it's a bad coil, if you dont get the trigger signal its a bad wire, connection, or module issue.
post up a picture of your coil!!!
m
Grand HDF Member
Joined: May 2014
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From: florida
I just so happend to come into possession of the FSM 1998 touring models, for the fuel injected bikes the stock coil is indeed single fire, it has three terminals on it.
one is power in at key on, battery voltage, the other 2 or trigger input for front and rear coil, the right side secondary terminal as the coil is mounted on the bike, is for the rear cylinder and the left terminal is for the front cylinder, make sure that your plug wires are in the right places, then check the 2 trigger wires for the ground signal that they get to fire the coil voltage to the secondary(spark plug), this isn't rocket science here. see my previous post.
m
one is power in at key on, battery voltage, the other 2 or trigger input for front and rear coil, the right side secondary terminal as the coil is mounted on the bike, is for the rear cylinder and the left terminal is for the front cylinder, make sure that your plug wires are in the right places, then check the 2 trigger wires for the ground signal that they get to fire the coil voltage to the secondary(spark plug), this isn't rocket science here. see my previous post.
m
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Joined: Jul 2018
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From: Ireland
Thanks for the responses I will be home next week and look at all these options. What would cause this problem before power reaches the coil.
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Grand HDF Member
Joined: May 2014
Posts: 3,822
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From: florida
This is the ignition system pick up/timer plate. I know that they call it the cam position sensor, but back before fuel injection, the name was different. How about a picture of your ignition coil?
m
m