'09 Uly won't start - no spark....

[andyfine]

Hi everyone,

I've read a few posts and really am at a standstill now with trying to diagnose and fix my XB12X that won't ignite any fuel

Background - events prior to no spark situation
I work away and left my bike with a mate to start every week or so
Upon returning after 3 months, he says that he started it a few times, but then all of a sudden it wouldn't start - I trust him
The battery was too low to crank so we tried push starting, like I've done a few times over the past 3 years of owning her
She popped a couple of times but I couldn't keep her running so we then hooked up a supplementary battery and cranked her over
Absolutely no fire at any attempt - so I thought I may need to change the plugs
I trailered my bike home and have tried the following:
Pulled the plugs and checked for spark by leaving them in the HT leads and grounding them with wires - nothing
Tried new plugs in the same manner - still no spark
Suspected the coil so removed it and tested all the windings - all as per workshop manual
Bought a Bluetooth Dongle and checked for any faults on ECMdroid - none
Performed a Coil test with the software - front and rear both spark properly
Checked RPM during cranking, plugs still removed - over 430RPM - ECM receiving signal (no Cam Sensor on this engine)
Downloaded a Buell Electrical Manual
Stepped through the Cranks But No Spark procedure

Not a gasoline quality issue - definitely a No Spark issue as I cannot see any at the spark plugs when cranking
No trouble codes
I don't have a breakout box so cannot perform live tests on the ECM, not really willing to pierce the wire insulation either at this stage
Battery on charge at 13.2V and drops to 11.0V when cranking - used a paralleled battery to make sure also
Fuel pump runs appropriately with ignition on Run and I can smell the fuel out the spark plug holes
Checked for 12V at coil - Good
Put an LED test lamp on both coils - No Flashing during cranking - No ECM output to trigger coils
Disconnected ECM and tested continuity between ECM and Coils - Good at around 0.3 Ohms
Tested the Crank Position Sensor at the ECM connector - 990 Ohms - Perfect
Checked Cranking output from Crank Position Sensor - over 6VAC - Perfect
I dug through my spares and found the original ECM thinking that this would certainly be the winner. Nope - still no spark
I can't understand a need to replace the Crank Position Sensor when I get a reading in the ECM - unless my reading is too low
Bought a clamp meter thinking there may be excessive load on the starter motor, or an internal fault. 130A and book says 140-180A is acceptable, I have the spark plugs still out, so that explains the lower reading

I think that I will have to replace the Crank Sensor to see if that improves anything. My reasoning is that if it's output is too low, then the ECM will not reach it's desired cranking RPM to trigger the spark output
Does anyone know what the minimum RPM the ECM needs to wake up and try to run the engine?

I bought ECMspy for my ECM - BUE2D and have available my EEPROM and a log during cranking - I don't think this is the issue as I've tried a spare ECM
Some screenshots of ECMspy before cranking and during cranking are hopefully attached here

Help is greatly appreciated

 

[user_deleted]

tremendous write-up andy. one of the finest pieces of trouble-shooting i've ever read. probably over-simplifying here but have you checked the following:
1-all your fuses....specifically the ecm fuse and the female spades that it plugs into?
2-a tps reset performed thru all of this? and if so has it been done correctly? on your 2009 it is simply the "twist throttle and cycle key switch" method.
3-any signs of cracking on either ecm where the harnesses plug into it? ulysses notorious for this problem
4-though i've never performed it my understanding is that the hall effect crank position sensor....you have NO cam postion sensor on your model....can be removed, checked for gunk build-up, and cleaned and reinstalled. might be worth trying. i just mention this as though i don't know how to read the charts you posted up....everything seems to point to the ecm not receiving a proper signal from the CPS sensor and doesn't know when to activate the coil pack. worth looking into.

 

[andyfine]

Thanks for responding LunaticFringe

So it turns out that my Buell, or maybe all BUE2D bikes, won't let the spark plugs fire unless they are installed in the cylinders. A friend told me yesterday that Harley did this to protect the ECM from burn out by monitoring the Back EMF from the spark plugs. If it sees too low resistance, it won't fire. So I reinstalled the plugs and it ran without fault.