Engine will not crank. I

[Pukmeister]

My suspicion all along has been the battery. 12 Volts is not a true indicator of the state of charge its just a rule of thumb, you really need to prove a battery is capable of supplying Amps under load, its Amps (current flow) that drives the starter motor not volts.

Most DC battery cells show 2.2VDC when fully charged, so a 6-Cell battery will be 13.2VDC or greater at full charge.

Your alternator should output 14.4 to 14.7VDC to put charge into a cell.

 

[Morety]

I think this is actually part of your problem,

Without wishing to seem negative or dismissive of the work you have done.

Focus on the real issue, not workarounds which are potentially steering you in the wrong direction

I think the fault either lies with the starter motor, or the starter relay / wiring

I know you say you've checked the starter and it looks good, that means nothing i'm afraid

I had a starter checked by a reman company who gave it a clean bill of health ,

( it was fu*cked) only a new starter cured the fault.

You need a quite specific set of parameters to be met before start occurs

The voltage to the starter needs to be above a set voltage / amps anything less, and it wont go

As mentioned, you need a clamp meter to see whats being drawn when you press the starter button.

You either have a power draw before the starter motor is energised,

A high internal resistance within the starter which the starter circuit cannot overcome

A failure of the relay /wiring to pull the low 12V side to high


Another thing which is troubling is why wont it fire?

If spinning the starter via external power, and all start parameters are met, the bike should fire ,

going back to basics

The start sequence should be (not necessarily in this order)

Ignition on

Ecu sends ready flag to fuel pump

Fuel pump primes and sends ok flag to ecu

Ecu sends ready flag to exhaust

Exhaust cycles and send flag to ecu ( an nok here wont prevent starting)

Cam and crank sensor pulse generators are set to on

Starter pressed - starter turns

Engine turns and injector fires & when TDC reached & spark generated

If ignition occurs - cam and crank pulse generators give increased readings

ECU seens values from Cam & Crank pulse generators and turns injectors on

If the Cam and crank sensor readings dont increase the injectors are turned off to prevent flooding

In order of cheapness

relay

wiring

battery

Starter

There was a similar post a while back where the OP had changed the starter (ebay or similar ) due to starting issues , and the bike still wouldnt start

turns out he'd replaced a faulty starter with another faulty starter

^^^^
This. I had a similar problem on one of my past bikes and it transpired to be the starter solenoid which wasn't providing enough current to crank the engine. All electrics worked properly, I could hear the relay clicking in and fuel pumps priming. Battery was healthy and ECU was fine. It was a faulty solenoid which was replaced for £27.

 

[Ali-bear]

The classic broken battery syndrome. It appears to work and hold charge but is unable to supply high current for cranking. Possibly a cracked terminal within the battery.

People are still using cars and spare batteries to jump start? Invest in a Li-based jump starter pack, readily available for about 50 quid.

 

[Bobnostart]

Dont start the car, a healthy car battery alone will give the required kick to a flat / low battery

you run the risk of killing the ecu on the newer bikes , they are sensitive to over voltage

Thanks for the detailed reply.
Just for your info, the battery is new, the start relay is new and the starter is new (from BMW, ouch).
Okay just to recap, with the bike battery connected directly to the starter, (spare starter relay fitted in the positive line, so no big blue spark when connecting the battery earth) the engine cranks over nicely when I energise the start relay.
With starter reconnected, bike battery fitted, ignition off, start relay energised externally, engine cranks nicely.
This proves beyond doubt the the battery, starter, starter relay and heavy duty wiring are good.
Now with the wiring but back so the ECU controls the start and a test lamp fitted in place of the starter, all works well. The interlocks (side stand & gear position) work as advertised. The lamp lights when start is initiated. The test lamp draws 2 amps.
With the starter reconnected and start initiated the start relay energises then trips straight away, almost instantly. Running lights go on and off quickly. No real drop in battery voltage that can be observed.
GS-911 download and only one fault left. "Exhaust Flap Servomotor Adjustment Error" . The flap is seized and I suspect it has been seized for many years and not the cause of the no start.
Very puzzling.
Will try and free the exhaust flap today.
Cheers

 

[Ali-bear]

You'll be kicking yourself if there's a problem with the immobilizer or the killswitch. Better check those.

 

[Mr Bean]

Dont start the car, a healthy car battery alone will give the required kick to a flat / low battery

you run the risk of killing the ecu on the newer bikes , they are sensitive to over voltage

Just about all voltage regulators (car and bike) will maintain 14.2v with the engine running. The same as the OP's bike.

How do you get 'over voltage' when the regulator keeps the car battery at the ideal 14.2v that the bike charges and is regulated to?

Fairly sure I've always read that you should only jump the other vehicle with the doner engine running, but take on board that the 100ah car battery will likely have more than sufficient reserve capacity on its own.

 

[Bobnostart]

Just about all voltage regulators (car and bike) will maintain 14.2v with the engine running. The same as the OP's bike.

How do you get 'over voltage' when the regulator keeps the car battery at the ideal 14.2v that the bike charges and is regulated to?

Fairly sure I've always read that you should only jump the other vehicle with the doner engine running, but take on board that the 100ah car battery will likely have more than sufficient reserve capacity on its own.

Good evening Gentlemen and fellow head scratchers,
Advanced the trouble shooting tonight. Slaved the old (fully serviceable) starter motor onto the start relay. Initiated a start controlled by the ECU and the starter (clamped on a Black & Decker Workmate) spun up a treat. Still off load but a lot more current draw than the test lamp. The only high current cable I've not bypassed in the one from the battery +ve to the start relay. Long shot but worth a try. So all I can see is the ECU does not like the current draw when all the bike electrics are connected.
Can't face the prospect of having to crawl to the BMW dealer at a cost of £108/hour. Ouch.

 

[Bobnostart]

Good evening Gentlemen and fellow head scratchers,
Advanced the trouble shooting tonight. Slaved the old (fully serviceable) starter motor onto the start relay. Initiated a start controlled by the ECU and the starter (clamped on a Black & Decker Workmate) spun up a treat. Still off load but a lot more current draw than the test lamp. The only high current cable I've not bypassed in the one from the battery +ve to the start relay. Long shot but worth a try. So all I can see is the ECU does not like the current draw when all the bike electrics are connected.
Can't face the prospect of having to crawl to the BMW dealer at a cost of £108/hour. Ouch.

As for the immobilizer and kill switch, they have been checked numerous times. I even checked the kill switch on the GS-911 download. All works fine.

 

[Bobnostart]

As for the immobilizer and kill switch, they have been checked numerous times. I even checked the kill switch on the GS-911 download. All works fine.

Good afternoon Gentlemen,
After six long weeks I finally had a breakthrough this morning. By-passed the +ve from the battery to the starter relay. Initiated a bike ECU controlled start, worked perfectly. In fact it gave me a shock. Let the engine run for awhile and noted 14.4 vdc from the alternator. So I have an insulation issue with the large battery feed. Will try and remove that part of the loom for inspection and/or replacement.
Thanks for all your help.

 

[Rushy]

Dont start the car, a healthy car battery alone will give the required kick to a flat / low battery

you run the risk of killing the ecu on the newer bikes , they are sensitive to over voltage

That’s what I said……

 

[Bobnostart]

That’s what I said……

Final feedback for R1200RT no start.
Bit of a cap in hand moment. After all my trouble shooting and cable replacing. The motorbike electrics and control units are perfectly serviceable. The penny dropped a few days ago (also refer to Pukmeister's comments). The new battery had lasted no more than two weeks. With it fully charged, I fitted it to the bike and got 11.3 volts. Not enough to turn a page. Bought a 18.9 Ah battery, fully charged it, fitted and bike voltmeter reads 12.6 volts. Tried a start, beautiful, almost instant. A great learning journey and an appreciation of how well the Beemer is built. Completely fooled by the first new battery.
Now the proud owner of a GS-911 which works well.
Hope to get a few rides in before winter sets in.
Once again thanks for all your help.

 

[Santa-2512]

That’s what I said……

You did oops, it the daft way requoting works ; )

 

[Santa-2512]

Final feedback for R1200RT no start.
Bit of a cap in hand moment. After all my trouble shooting and cable replacing. The motorbike electrics and control units are perfectly serviceable. The penny dropped a few days ago (also refer to Pukmeister's comments). The new battery had lasted no more than two weeks. With it fully charged, I fitted it to the bike and got 11.3 volts. Not enough to turn a page. Bought a 18.9 Ah battery, fully charged it, fitted and bike voltmeter reads 12.6 volts. Tried a start, beautiful, almost instant. A great learning journey and an appreciation of how well the Beemer is built. Completely fooled by the first new battery.
Now the proud owner of a GS-911 which works well.
Hope to get a few rides in before winter sets in.
Once again thanks for all your help.

What battery did you go for?

Motobatt or Oddysey are considerd the mutts, or you could go lithium f you want to go leftfield