Engine dies suddenly when warm

[h_c_82]

Hi,

I have a problem that's driving me nuts! The bike is a 2002 FXDX, Carb, mostly stock.

The problem is that as soon as the engine is a little warmed up it will die suddenly without any sputter or hesitation. Like you hit the kill switch. It will die while riding or in idle, no matter what speed or load. Lights stay on. It will not restart just crank over until a few minutes passed by (so as soon as it cooled down a little?). During that time there is no spark. There is also no check engine light on and there are no historic codes stored. Here is what I have done so far without success:

- hotwired the ignition switch (first time it appeared on the side of the road...)
- checked all connectors and battery cables (cleaned and greased them)
- replaced the TSM unit with a spare one I had (BAS issue...)
- replaced the coil

Next thing will be changing the ignition module (though everybody says they never fail?). I also have a spare Crank Sensor that I can use though I think a bad CPS would throw a code, wouldn't it? I am not sure how much these early twin cam ECM's are able to diagnose.

It certainly looks like a heat related problem and as the power does not entirely break down I would exclude the main circuit breaker or the battery. At the moment I am strongly leaning towards the ignition module.

I came across a lot of posts with similar problems here or on other Forums but no one really fixed it (besides the known BAS or main circuit breaker issues). At least they haven't wrote about it. So I would really appreciate a little input. I probably haven't thought of everything possible and maybe some of you guys had the same problem. It seems to be quite common from what you can read...

Many thanks

Holger

[86fxwg]

Most likely crank sensor,BUT...that don't explain no √ engine light. My money is on the module.
When the problem happens do u have b+ to the coil ?


86

[Jim Bronson]

I'd go with the module next, since it seems to be heat related. Try to beg one from someone for a test. Modules are very reliable, but they can fail.

[smoserx1]

My ignition module failed (99 FLHT) after about 110000 miles.  Got to where it would briefly cut out (like a split second, just enough to create a backfire in the exhaust), but initially this occurred once every 3 months or so and it got steadily worse.  Finally it was about every  10 minutes.  Replacement fixed it.  I also got no codes, so I too would suspect the module.  They are reliable, but they will not last forever.

[h_c_82]

Thank you so far...

86fxwg, what do you mean by b+ on the coil? (Is this a stupid question?)
You mean does it get supplied with power?

I am borrowing a module from a friend of mine who has a 2002 low rider. Lets see what happens...I have just a bit above 30K miles on it, btw. So Iahve a bit to go until 110  But then again its 13 years old...

[14cvoultra]

 Replace the crank sensor I had a 2000 softtail would do the same thing 3 dealers later not fixed
because no codes I just replaced it my self fixed problem

[86fxwg]

Thank you so far...

86fxwg, what do you mean by b+ on the coil? (Is this a stupid question?)
You mean does it get supplied with power?

I am borrowing a module from a friend of mine who has a 2002 low rider. Lets see what happens...I have just a bit above 30K miles on it, btw. So Iahve a bit to go until 110  But then again its 13 years old...

12 volts to coil. Re-read & u ran a power wire so u can void that comment.

86
Throw a module at it.
Or dead cold take a heat gun or the wife's blow dryer & warm the module up. 

[bwdogman]

Had one do the exact same thing tried all things listed above, ignored the battery because it was only a couple years old but replaced it and the guy who owns it says it hasn't done it since. Must of had a bad connection in the battery itself and had to run and vibrate before quitting.

[h_c_82]

Ok, looks like I am on the right track. First thing will be the ingition module change.
If that does not work, new CPS. And if that fails too, battery.

I'll keep you updated!

[PoorUB]

If you are going to throw parts at it, start with the lowest priced part and work your way up.

[joe_lyons]

Do you just have the stock ign module or is it an upgraded one? A bad cps will not throw a code.  I would go with the cps first.

[86fxwg]

Do you just have the stock ign module or is it an upgraded one? A bad cps will not throw a code.  I would go with the cps first.

Correct,but he also looses his √ engine light when it doesn't start.
I have not looked at a wiring diagram, I'm guessing module has something to do with the light.

86

[motorplex88]

In this not one of the years that had 50 amp main breaker problems ? Just a suggestion, I'll be quiet now.

[Admiral Akbar]

When the motor dies, does the start button not work until you cycle the ignition?

[h_c_82]

Ok fixed. It was the CPS! I thought this thing would throw a code. But maybe just on the EFI models...
Luckily I had all the parts that I cahnged as spare lying around or could borrow them from friends. So it was a cheap fix.

Thank you all for your comments!

[joe_lyons]

Bad cps dosent throw a code on FI models either.  The tale tell is no rpm shown while cranking.   Glad you got it fixed.

[14cvoultra]

Good fix glad you did not have to buy all them parts. I still have all the extras the shops
changed out and sent me on my way only to quit again 20 miles down the road.
But I am a bit wiser now.

[Admiral Akbar]

Bad cps dosent throw a code on FI models either.  The tale tell is no rpm shown while cranking.   Glad you got it fixed.

DTT will throw a code if the crank signal is lost and the there is still power to the module.. You get the same code if you stall the motor.. DTT doesn't remember codes tho.