Home › Forums › General Discussion › TECH INQUIRY – 2009 BMW K1300 GT Sluggish cranking to start. › Reply To: TECH INQUIRY – 2009 BMW K1300 GT Sluggish cranking to start.
The new battery idea would sure be a great place to start, especially if your existing battery is more than a few years old. If you don’t want to spend the $$$$ on a new battery then at least have the battery load tested.
With hot cranking problems the obvious place to start the troubleshooting is to do a hot engine voltage drop test on the starter 12v supply cable from battery positive post to starter solenoid 12v supply stud, and on the starter ground side from starter housing back to battery negative post. Put voltmeter on low scale, like 10-20 VDC then put one meter lead on battery positive post and other lead on starter solenoid large cable stud to parallel the battery cable from battery positive post to starter solenoid large battery cable stud then hit starter button. Then place voltmeter leads between battery negative post & clean metal on starter body the hit starter button. The lower the voltage drop the better with anything under .25v great, anything under .5v OK and anything over .5v showing a possible problem, and anything over a volt being something that positively needs addressing.
If a high voltage drop is found then you have excessive resistance in that part of the starter circuit.
Otherwise a trip into the starter might be required to see if you have a hot starter armature drag issue due to worn bushings or something like a debris shield is loose inside the starter.
Hot engine starting issues can be somewhat difficult to diagnose easily as a tight piston or internal engine drag can act the same as a tight starter or low starter current.