New "Old School" guy - bike turns over but not firing.
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6th Gear
Joined: Aug 2025
Posts: 12
Likes: 12
From: Cleveland, Ohio
New "Old School" guy - bike turns over but not firing.
I wanted to introduce myself and thank anyone who can give me suggestions and or ideas on how to repair my 2003 Fatboy. I'm an older guy who finally achieved retirement. My first bike was a 1969 Triumph Bonneville, next one was a 3 cylinder Trident and first Harley was a 1976 Shovelhead. Worked on all my bikes and cages but with time on my hands would like to figure out my present problem with by fuel injected twin cam 2003 Fatboy. My bike turns over but no firing. Checked fuses and then checked with spark - no spark. I'm a retired Refrigeration Tech so I can handle checking anything electrical and or mechanical if pointed in the right direction. Thank you, John
I received news from a buddy that it could be my voltage regulator. Can anyone give me info on how to check it? Thanks in advance
I received news from a buddy that it could be my voltage regulator. Can anyone give me info on how to check it? Thanks in advance
Last edited by Excon669; Aug 1, 2025 at 03:31 PM. Reason: New information
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,416
Likes: 6,366
From: Honah Lee
Welcome to the HDFORUM.
Unlike the 2004, you bike blinks codes. If its not getting a crank sensor position reading, it will not fire the coil.
Also, won't turn on fuel pump to run full time while running. Should set a code if it cranks over 5 seconds without that reading from sensor. 2004 will. Not sure about 03.
Do you hear the ECM 2 second or so timed run of the fuel pump when you key on?
Check codes and report back. (See YouTube for how to get and understand those blinks.)
It's not voltage regulator. You check it crudely running at 2000. Should be about 13.5 to 14.9.
You should have about 9.7 cranking to show battery OK. Should read about 12.6 -13.1 after a good maintenance charge and charger removed and keying on and off to kill surface charge.
The crank sensor is just to left of oil filter. (sitting on bike) It's a electrical magnet from about 5 volts from ECM )
They occasionally go bad. Shows about 1 ohm resistance, so it's hard to check. It will thow a code but I am not sure just how many checks your primitive system is.
Coil is an easy ohm check. That should be checked first probably.
By then, community team will move your thread to proper area.
Fill free to come back here and post a new thread to say hello. This area is primary just to say hello.
Unlike the 2004, you bike blinks codes. If its not getting a crank sensor position reading, it will not fire the coil.
Also, won't turn on fuel pump to run full time while running. Should set a code if it cranks over 5 seconds without that reading from sensor. 2004 will. Not sure about 03.
Do you hear the ECM 2 second or so timed run of the fuel pump when you key on?
Check codes and report back. (See YouTube for how to get and understand those blinks.)
It's not voltage regulator. You check it crudely running at 2000. Should be about 13.5 to 14.9.
You should have about 9.7 cranking to show battery OK. Should read about 12.6 -13.1 after a good maintenance charge and charger removed and keying on and off to kill surface charge.
The crank sensor is just to left of oil filter. (sitting on bike) It's a electrical magnet from about 5 volts from ECM )
They occasionally go bad. Shows about 1 ohm resistance, so it's hard to check. It will thow a code but I am not sure just how many checks your primitive system is.
Coil is an easy ohm check. That should be checked first probably.
By then, community team will move your thread to proper area.
Fill free to come back here and post a new thread to say hello. This area is primary just to say hello.
Last edited by Jackie Paper; Aug 1, 2025 at 04:32 PM.
Tourer
Joined: Oct 2012
Posts: 344
Likes: 121
From: Hakuba Japan
I find the factory service manuals to be the best investment you will make.
Heres a link to a free pdf in the interim.
Scroll down.
https://www.lowbrowcustoms.com/blogs...Hl#heading3-54
Heres a link to a free pdf in the interim.
Scroll down.
https://www.lowbrowcustoms.com/blogs...Hl#heading3-54
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Road Warrior
Joined: Sep 2021
Posts: 1,965
Likes: 1,421
From: Black Hills of SD
The factory service manuals. Main one, the electrical one and even the parts one - ALL will be your best friend.
There are many things that will stop spark on these bikes and many, many things to check.
For the interim. Here is where I would start.
Ignition on, fuel pump goes through its priming mode. That tells you that the safety systems are probably working. Crank and no spark tells you it is probably electrically not getting a signal from somewhere that it needs. If no codes are found, and I just had to start working on it without a manual. But you will need to know the checks to see if any of these are culprits. voltage and resistance values for all of them, including the R&R are in the manuals. I would start with these.
CPS
Coil
Safety circuits that cut out ignition.
There are many things that will stop spark on these bikes and many, many things to check.
For the interim. Here is where I would start.
Ignition on, fuel pump goes through its priming mode. That tells you that the safety systems are probably working. Crank and no spark tells you it is probably electrically not getting a signal from somewhere that it needs. If no codes are found, and I just had to start working on it without a manual. But you will need to know the checks to see if any of these are culprits. voltage and resistance values for all of them, including the R&R are in the manuals. I would start with these.
CPS
Coil
Safety circuits that cut out ignition.
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Seasoned HDF Member
Joined: Mar 2021
Posts: 18,133
Likes: 3,638
From: backwoods
Charging system has nothing to do with spark . If battery turning over good, probably ok. But doesn't hurt to put on charger.
You can check voltage to coil. Crank sensor is input to coil, AC in put
Leave plugs in, and just put a good plug on wire. I am not sure your year, but some years care but some years need compression to fire.
I am not sure you can pull codes from dash on 2004 delphi fuel injection. Does check engine light stay on or come back on?
Some times you can find old service and electric manuals cheap on eBay. You need service manual to own this bike in my opinion
You can check voltage to coil. Crank sensor is input to coil, AC in put
Leave plugs in, and just put a good plug on wire. I am not sure your year, but some years care but some years need compression to fire.
I am not sure you can pull codes from dash on 2004 delphi fuel injection. Does check engine light stay on or come back on?
Some times you can find old service and electric manuals cheap on eBay. You need service manual to own this bike in my opinion
Last edited by Rounders; Aug 2, 2025 at 08:03 AM.
