2008 bigdog k9 quits when hot

[brazo]

My K9 just quit on me today when it got hot, I let it cool off and it started back up, got hot again and did the same thing anyone have a idea on what could cause this

 

[Five Five]

If your system is (EFI) fuel injected I recommend an oil cooler

 

[Brew]

Could it be vapor locking?

 

[brazo]

I am checking on it to see if its vapor locking, I been reading alot of posts about this problem, I was just thinking it could be that or the ehc unit

 

[Olde Man]

I repaired a sportster that had a bad crank position sensor and that is what it did.

 

[BigDogBro1]

I repaired a sportster that had a bad crank position sensor and that is what it did.

This is the recommended first thing to test.

You should carry a spark tester with you and next time this happens, pull a plug wire and test for spark or check the crank sensor. It should output about a 3 volt (AC) signal when the engine cranks over.
This will eliminate all the other bullshit.

You need to know why it's dying before you start the repairs...right?

Do not crank over the engine without sparkplugs connected and grounded or a spark tester installed.

Always RESET the EFI ECM after reconnecting the battery if you and an EFI engine. Instruction label near battery.

Never work on any electrical/electronics connections with the battery connected.

 

[bigdogtech01]

This is the recommended first thing to test.

You should carry a spark tester with you and next time this happens, pull a plug wire and test for spark or check the crank sensor. It should output about a 3 volt (AC) signal when the engine cranks over.
This will eliminate all the other bullshit.

You need to know why it's dying before you start the repairs...right?

Do not crank over the engine without sparkplugs connected and grounded or a spark tester installed.

Always RESET the EFI ECM after reconnecting the battery if you and an EFI engine. Instruction label near battery.

Never work on any electrical/electronics connections with the battery connected.

I agree :2thumbs:

 

[brazo]

It just happened again and I checked it with spark tester no fire

 

[brazo]

it cooled off about 15 minutes ha spark and it fired back up

 

[JDog]

Brazo, let me know if you find your problem. I have a 08 K9 doing almost the same thing but mine doesn't have to be warm it will do it any time. It is getting worst with time. The problem I have is when it quits it will start back up as soon as you hit start. It will not stay dead. I just put a new PDM in it (had other issues too) that didn't help. That includes a new back bone wiring harness and the power harness.

 

[07bigdog]

My 07 K9 was doing the same thing. My charging system went out. Replaced the stator, rotor,crank position sensor and voltage regulator and battery was also testing low so replaced. Put on 2000 miles since and running excellent. I also have a PDM kit installed.

 

[JDog]

07, you thinking it was the crank sensor making it stop running. Looks like all the other was for charging other than the PDM. And would it restart right a way?

 

[jaggerz]

I work as an auto tech and have seen crank sensors behave this same way. Pull it out of the block and check to see if the end is cracked in any way. If not, might be worth a try and replace it anyway. Good luck.

 

[wrench]

symptoms are what bad electronic ignitions do. run till hot. usually about the same distance each time.

 

[Iman]

did you check the gas cap to make sure its venting correctly

 

[bearman]

I realize this is an old thread but for information.

On the ‘05s and up it is easy to check the crank sensor. Look at the 3 LEDs on the ignition module. On my ’06 mastiff it is under the left side plate (oil tank cover).

Red should be on when ready to start (key on, run button pressed), when spinning over trying to crank the blue and yellow LED should alternately blink. If no red LED, then you don’t have 12 volts to ignition module. If you get red LED but blue and yellow do not blink when cranking, then bad crank sensor.

The symptom of turning off when hot and starting again after cooling off, then getting progressively worse is what mine did till it left me stranded. It was the crank sensor. Any Harley crank sensor for a big twin will fit, you will just have to splice the wires because the Harley connector is different.