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At wits end with Startus Interuptus

On the suggestion that the ECU is stopping the process due to low volts, I tried my Norge yesterday. Put the dash to display volts and hit the start button. Motor churned but didn't start. Volts reading went down to 9.0 volts. It started on the second go. So low volts should not be the culprit in the original post assuming the battery is good.
 
Brian UK said:
On the suggestion that the ECU is stopping the process due to low volts, I tried my Norge yesterday. Put the dash to display volts and hit the start button. Motor churned but didn't start. Volts reading went down to 9.0 volts. It started on the second go. So low volts should not be the culprit in the original post assuming the battery is good.
Click to expand...
When you say the motor "churned" do you mean it was turned over by the starter? If so, this is a different condition from what I have going on. All I have is a loud thunk from the solenoid when hitting the start button, no starter turning.
 
Earl Bowman said:
When you say the motor "churned" do you mean it was turned over by the starter? If so, this is a different condition from what I have going on. All I have is a loud thunk from the solenoid when hitting the start button, no starter turning.
Click to expand...
I'm aware of that, I can get the same problem too. But what I was trying to show was that it's not low voltage seen by the ECU which is stopping the process, as if that were the case, mine would not have allowed the starter to turn at 9.0 volts.
 
I imagine he has run a wire from the battery to the solenoid directly or via a relay. it drastically shortens the convoluted route the start button on the handle bars takes.
 
The start button on the handlebars is not part of the circuit to the solenoid though. It just tells the ECU to start the engine.
The customary wiring mod to the start relay cuts out about 5 feet of wire, and lots of connectors, including the contacts in the ignition switch.

But another mod, which I was tols was a part of a TSB, was to incease the weight of the wire from the start relay to the solenoid. Anything to reduce voltage drop. And those spade connectors are known to lose their spring over time, only needs the one on the solenoid to open up a bit.
 
The startus interuptus mod does shorten the path for the electricity, and removes some of the things that can reduce the voltage. Just because the power for the starter doesn't go through the switch on the handle bar doesn't mean the system isn't overly complicated as designed and manufactured by the factory.
There should be a thread on here that tells you how to re-wire it to improve the voltage the ECU sees from the battery when the start is attempted.
 
I haven't found that a problem. As I said a few posts up, mine went down to 9.0 volts on the dash while still starting. It's the volts getting to the solenoid coil which seems to be key. But if you want to ensure the ECU sees better voltage, just install the capacitor and diode as shown in the wiring diagram.

Sticky grease inside the solenoid can also be a factor.
 
GuzziMoto said:
The startus interuptus mod does shorten the path for the electricity, and removes some of the things that can reduce the voltage. Just because the power for the starter doesn't go through the switch on the handle bar doesn't mean the system isn't overly complicated as designed and manufactured by the factory.
There should be a thread on here that tells you how to re-wire it to improve the voltage the ECU sees from the battery when the start is attempted.
Click to expand...
pswiatki, POLSKA here! Well... This might not be as easy as one would like it to be - one would have to bypass the wire harness to route the battery voltage (power supply to the ECU) using thicker wire. Perhaps it would give some desired results, who knows. Question is: which pin on the ECU gets internally sampled to check the power supply voltage (don't have the diagram in front of me - maybe this is trivial, maybe not)? Still... It seems to be the ECU sensitivity issue. I have several scope captures with crank pulses in "my" thread. The ECU designers did something "interesting" with the sampling of the Vcc (power supply) voltage, I'd say. Or the module is marginally able to survive deep Vcc drops during the crank phase.
 
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Have you tried another known good battery, as a means to determine whether your one is at the end of its life? They all can look good until the acid test.
 
Yes, good point! If I remember correctly: when I did not ride my bike for long enough (could be a week or two - not more than that) the probability of getting engine start issues was non-zero. When ridden regularly - no problems. The last thing I did was to remove the battery and charge it properly. After that, the problem was gone which led me to believe something (immobilizer?) had to draw enough current to deplete the battery to a state in which ECU was reluctant to allow cranking when so commanded. :rolleyes:
Since I knew I would not ride the bike during winter I removed the battery from the bike and charged regularly (with an electronically controlled unit, so I could have just left it on all the time) and had no issues when I put the battery back in the bike a week ago. No nasty surprises.
 
Finally received the last of the new relays for the Breva. (Backordered to the factory) I have now changed all 5 relays under the seat and it has made no difference. Startus Interuptus rules. Where should I look next for a solution?
 
I feel your pain, Earl. I had the "thunking" problem too, which occurred even after fitting the MPH solution. Eventually I traced it to a poorly fitting tab on the starter solenoid. It was loose and lolled around. I could flick it with my finger and the bike would go from a starter to a non-starter. I snipped it off and fitted a new one and the starting problem disappeared. Years later I had problems again. It turned out that the battery charging was intermittent. Another rider told me that my headlight wasn't always on. Traced to a faulty 30 amp fuse. Replaced fuse, problem resolved.
 
The whole system is marginal, batteries have got smaller, so they drop voltage more when the starter load is present. Manufacturers have cut down on wire size as copper is so expensive, and the original design was rubbish to say the least.
Though I did that start relay wiring mod years ago, I have still been plagued by the problem.
Last weekend I added a new wire from the start relay down to the solenoid, using wire of about twice the cross sectional area. I also used the same heavier wire for the run from the relay back to the battery. Starting far more reliable now.
If you don't get enough volts to the solenoid, it won't pull in fully so the engine won't spin. It's all down to voltage drop through the various bits of wire and connectors.

While I was in there, I checked the two main fuses in the block 40 & 30 Amp. 3 of the 4 wires to the fuses were cooked, the insulation was brown and brittle. It wasn't the spring in the spade connectors, it was the original factory crimp which had got corrosion in there, thus creating a high resistance and heat. Same could be happening on every other crimped connector.
 
Hmm, just had a bout of startus Interuptus and had a relay installed.
It improved things as it always will regardless of if it baulks or not but..... A secondary thing was picked up by by my local auto electrician.
He highly suspects that the the lead earth brush is arcing and prematurely burning out the commuter.
Even showed me a benched example of what's going on.
It's possible to replace the brushes and true the commutator and seriously won't hurt regardless.
Chris.
 
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