Starter fuse B blowing

[Brian UK]

There have been several reports of the 15 Amp fuse supplying the starter solenoid blowing, resulting in nothing happening when the start button is pressed.
Happened to me yesterday on the Norge, but at least I was aware of the issue and fitted a new fuse straight away.
So I did a couple of checks today.
I took the fuse out and put my analogue meter in its place, meter on 10 Amp FSD (its highest scale).
Pressed the start button and the needle went off the scale, suggesting that the current drawn by the solenoid (plus the front side lights and number plate light) is closer to 15 Amps.
Anyone got a meter which will read more that 15 Amps DC and who could try this themselves?
If my thinking is right, the fuse is too close rated, and the solution would be to fit a 20 Amp fuse.

 

[mwest]

I would think long and hard before fitting a larger fuse. The fuse is designed to blow when current gets high enough to damage components, or burn wire or connectors. Unless you know everything else in the same circuit is capable of handling the larger current rating, you could be making a big mistake.

A less dangerous option would be to get a slower fuse, one that has the same rating but takes longer to blow. Starter motors have a high surge when first starting so a fast fuse may blow where a slower one may be fine. Fuses have amp/time curves associated with them. A look through the manufacturers literature may help to find one that will take the current of the starter long enough to eliminate the nuisance fuse blowing.

 

[john zibell]

A less dangerous option would be to get a slower fuse, one that has the same rating but takes longer to blow.

Any idea where to get them? I tried searching for ATC type slow blow fuses and only found the old style glass type.

 

[Holt]

The problem is well known from the 750 Brevas which came with 10 A fuses, but later on was delivered with 15 A. As the starter motors are the same in all models, it's a bit astonishing that you're having the problem with a 15 A fuse.
Check all connections, that they are tight and clean. Loosen, adjust, use some electronic device cleaner and contact spray, be sure all spade type connectors are tight also - including the present fuse holder.
As said, fuses are for protection. It is not obvious that one can with impunity change to a larger size, even though spare-kits are available.

You could make your own Bosch-type fuse holder, and try a slow tube-type fuse, but I suspect that common automotive-type fuses already are slow and only are produced in a single execution, "Fast Acting". I haven't succeeded to find a comparative characteristic curve.

http://www.littelfuse.com/data/en/Data_ ... ATO32V.pdf

 

[AllanK]

Oh yes, I remember this.

There I was about halfway between Ayers Rock and Kings Canyon in 2008 (read "in the middle of nowhere") on the 2007 Norge when I stopped at one of these roadside parking areas. jumped back on after a short bbreak and hit the starter. Zippo, nuthing. Inspect- blown starter fuse and so it was for aout the next four fuses that I was carrying. Bump start and got to Kings canyon. Couldn't fix it or work it out. So the next day push start and off to Alice Springs to a mechanic.

You reckon you have trouble when you don't take your helmet off at a servo, try filling up with the engine going and see what happens.
Got to Alice and the harley dealer (no guzzi dealers there and the charity ride I was on were all going to the harley shop). Usually I'm the first to put shite on a harley but those guys couldn't do enough and a Saturday afternoon. Hello Alice Springs Harley. Great shop.

After about two hours and 15 fuses (how many times did it start and we thought that we had it right till it blew again) we got the Norge going and it hasn't had the same problem again after some 15000klms.

If memory serves me right we put a bigger fuse in (20amp???)for a couple of starts and then went bach to the standard 15. Never did work out what the problem was. just wanted to get the bike home and by the time I did it was gone. Heard a lot of suggestion but no real answers.

I agree with the posts that it may not be the way to go but it seemed to sort my matter out. I can tell you thought that I was pretty concerned riding back down through the centre of Australia to Adelaide and then across the country to the east coast and to Bundaberg. A lot of mmiles but no more trouble

 

[Brian UK]

This was a once only event so far. It didn't blow any others.

I know what fuses are there for, so I don't suggest change without giving serious consideration to this.
There may well be a difference between the Norge and early B750s, as on the Norge, the front side lights and number pate lights are also on that fuse, adding another 1.3 amps according to my meter.

I had previously been over the electrical system with contact cleaner to all connections, and all are tight too.
However, normally a poor connection through a spade will reduce the current rather than increase it. Ohms law and all that.

So, to get back to the original question, is anyone in a position to measure the current taken by a Valeo starter solenoid?

 

[Holt]

According to Ohms law, I think it's voltage that will be reduced, but don't mind.
Most multimeters has a 10A - limit, and I won't risk my Flukes.
I can try with a clampmeter, I may have one with a hold on peak.

 

[Kevin.NZ]

Hi Brian,
I have a 07 breva 1100 and I have a meter that reads 20 Amps DC, I removed the 15 amp fuse and inserted the probes and started the bike, I got a peak current of 6 amps and the bike started ok. I then put a suspect/flat battery on the bike and measured the current as I pressed the starter button, there was a clonk as the starter relay and solenoid engaged and the engine did not turn over, I was very suprised to see a peak current of 19amps which stayed there for 5 seconds until it timed out. This would have blown the 15 amp fuse. Maybe this fuse is prone to blow if the bike has a flat battery and not enough oomph to fully engage the solenoid on the pre engaged starter or bad earths/connections on the starter circuit.
Cheers Kevin

 

[john zibell]

Hi Brian,
I have a 07 breva 1100 and I have a meter that reads 20 Amps DC, I removed the 15 amp fuse and inserted the probes and started the bike, I got a peak current of 6 amps and the bike started ok. I then put a suspect/flat battery on the bike and measured the current as I pressed the starter button, there was a clonk as the starter relay and solenoid engaged and the engine did not turn over, I was very suprised to see a peak current of 19amps which stayed there for 5 seconds until it timed out. This would have blown the 15 amp fuse. Maybe this fuse is prone to blow if the bike has a flat battery and not enough oomph to fully engage the solenoid on the pre engaged starter or bad earths/connections on the starter circuit.
Cheers Kevin

Kevin,

Very informative test. Thanks for telling us the result.

 

[Brian UK]

Kevin, I think you may have struck the jackpot. I have also been posting this on our club forum in the UK, and following a pointer to a website, had just come to this conclusion myself.
The solenoid has two coils, explained here better than I can write it.
http://www.picoauto.com/tutorials/ferra ... ics_2.html
It comes down to if the battery volts are low and the solenoid doesn't pull in far enough,both coils are energised until the time out. If the battery is good then the time the pull in coil is energised will not show up on a digital meter, it's too short.
Though this will still be the 19 amps, plus the 1.5 for the lights which are also fed from this fuse, suggesting that the fuse is going to have a hard life. The fuses used are not particularly quick blow type fortunately.

The only problem with this hypothesis is that I had no problem starting before the fuse went, and no problem once I had changed the fuse, indicating that the battery was not that low. But worth investigating anyway. I have recently been over all the terminals and earth connections, cleaned and smeared with vaseline. I have checked again and they are all still tight.

 

[Brian UK]

OK, just picture this situation. Just occasionally the pinion may not mesh with the flywheel ring. In this case, the throw in coil on the solenoid will remain energised until the ECU times out. This will almost certainly blow the fuse.
So there may be no problem as such, just the very occasional odd circumstance.

 

[Holt]

OK, just picture this situation. Just occasionally the pinion may not mesh with the flywheel ring. In this case, the throw in coil on the solenoid will remain energised until the ECU times out. This will almost certainly blow the fuse.
So there may be no problem as such, just the very occasional odd circumstance.

I'm convinced that I've experienced exactly that situation.
On a very hot summers day in the middle of the autostrada between Venice and Milan. The B750 kept blowing fuses after a short water tanking stop (for me), untill I engaged a gear and pushed the bike a bit back and forth.
Then it was as normal, showed the sunny side up and started with no further issues.

 

[Kevin.NZ]

Hi Brian,
interesting site, the starter on mine and your bike is a pre engaged type, the solenoid throws the cog into the ring gear and when it is fully meshed it then connects the battery directly to the motor. This overcomes the problem on old starter motors where the spinning of the starter motor actually throws the cog into the ring gear, this sometimes caused the teeth to jam and the fix was to rock the car/bike back and forwards in gear to flick the cog out, some starters even had a square drive on the end so you could turn it with a spanner. It generally happened on a worn ring gear as most engines always stop in the same poition. I have replaced a few ring gears in the past. On cars occasionally a pre engaged starter will not disengage due to crap on the shaft, if its an Auto you cant rock the car in gear, removing the starter is a drag and I found a sharp tap with a hammer on the starter body will release it. If the heavy duty contacts on the solenoid inside the starter motor are faulty then not enough current will flow to spin the starter motor and a stalled motor will alway draw heaps more current than a spinning one and therefore blow the fuse.
Cheers Kevin

 

[Brian UK]

The fuse in question does not supply the motor winding, so a stalled motor will not affect it.
Also beware "tapping" the body on any Valeo starter, the magnets are only held on with gorilla snot and come loose very easily.

 

[RJVB]

Brian: which lights? The lowbeam turns on only when the engine turns...

 

[Brian UK]

The two 5W side lights.