I had the tins removed from my ‘08 FXDF & sent them off for painting. The only parts removed from the bike were the fenders, battery & fuse panel covers, tank and dash.
2 weeks ago we (reputable local bike mechanic & I) reassembled the bike but it would not start, no spark. We’ve cleaned and checked grounds, checked all the fuses, cleaned connections, checked codes, replaced crank position sensor (got a code on it), checked continuity on the coil, checked power to the coil, replaced a weak battery, basically gone through everything we could think of and it is still not getting spark.
It turns over fine, fuel pump cycles on like it should and appears to be building pressure like it should. Fuel injectors at working as well.
Does anyone have any suggestions on what else to try? Is there something we could have missed that would prevent the coil from firing?
This is my first bike in 30 years so, I’m not used to trouble shooting bikes. My budget has just about run out so, I don’t just want to start throwing parts at it until it runs.

 

How are you checking for spark. Plugs must be installed for computer to sense compression. Use spare plug to check for spark.
My wild guess would be that the fuel line quick disconnect is not properly seated.

 

I wasn’t aware of the bike having any sort of compression sensor so I was checking for spark the old fashioned way. By pulling the plugs and grounding them to the heads.
Thanks for the heads up!
the fuel line QD is on right. First thing both of us checked when it wouldn’t start.

 

Are the plug wires reversed? Also as stated above, disconnect and reconnect fuel line to tank.

 

It's in the diagnostic service manual. Right after first Warning..in Note Spark will not be present with both plugs out. When checking for spark, Use spark plug tester with both plugs installed and one wire connected to spark plug tester with it grounded to the engine.

I have a plug I use with an alligator clip held to plug with a hose clamp.

Someone on here said this was not part of the ion sensing that controls the spark retard doing this but some other means that made sense.

This comes up on here at least once a month. Harpo, be sure to get back if this is your problem.

 

Thank you very much for your help.
I will update when I get it checked.

 

It is not part of the ION sense. I have explained this numerous times on this forum so the super simple answer is that the system has no cam sensor so it uses flywheel deceleration to determine that it's in a compression stroke so the plugs must be in.

 

I thought it was you. At 70, I don't dare let RIP know how much I forget. What's bad is I remember the timing setting on my old 69 Firebird and not what I ate for breakfast yesterday.

Crank Position Sensor detects flywheel deceleration from the compression load that slows the starter rpm slightly.

Does it actually use that ever time it starts cranking to determine where motor is in relation to TDC to determine a fire stroke or does the missing tooth on the crank wheel of the crankshaft do that?

 

Hi Ripsaw, It works like this:
The missing tooth on the flywheel tells the ECM TDC information of the pistons.
Because it is a 4 stroke cycle, it takes 720 degrees of flywheel rotation to complete.
In that 720 degrees, the piston is at TDC 2x (Compression & Exhaust)
Because there is no cam sensor, the ECM must find phase - it needs to know which one is compression so it can throw spark.
On compression, the flywheel speed slows (ever so slightly, but the ECM can see it easily)
It then cross checks with a signal from the MAP sensor and it has phase and can then throw spark.

 

I understand the crank slowing thing for finding which cylinder is on the compression stroke but am not sure how the ECU cross checks with the MAP sensor. On the compression stroke, the MAP does not seem like it is doing anything. Both pistons are both going up tho one leads or lags the other buy 45 degrees.