Trouble Starting When Engine Is Hot

[Orson]

Recently had some starter problems so, the mechanic said he cleaned all the connections, new battery, new relays, put grease on the battery terminals and the starter is a couple of years old.

 

I'm currently on a trip and the bike ran normally for the first three days. At the end of the third day, I stopped to fill up with gas then, hit the starter. After a 1 second delay, it started up and I went to my hotel a short distance away. When I turned it off, I tried to re-start it but, I didn't hear the fuel pump. Clicking it into neutral got the fuel pump to work but, pressing the starter button only resulted in an electrical click sound. I tried moving the handlebars from side to side but, no luck.

 

I carry spare relays with me so, swapped them out but, still no success. Also checked all the fuses. After a couple of hours the engine had cooled off and I tried to start it again. This time, it fired right up, without a 1 second delay.

 

The next day, I stopped to fill up with gas. Pressed the starter and got the electric click sound. Immediately hit the starter again and it fired up.

 

As far as I can tell, it starts up fine while the engine is cool but, has problems after it gets hot.

[fotoguzzi]

to me that sounds like a loose battery connection or failing battery..

[chamberlin]

You didn't state what generation of bike you have. Could this be the old style (external) fuel pump vapor locking due to engine heat? The '03+ model year bikes have internal fuel pumps which solved this problem.

[docc]

to me that sounds like a loose battery connection or failing battery..

 

to me that sounds like a loose battery connection or failing battery..

+1.  Not only the battery connections themselves but especially the main ground to the gearbox. Be sure it is clean of grime AND paint - use a "star" washer under the connector and seal over with petroleum jelly.

 

Check that the 30 amp main fuse is not melted or the blades damaged.

[chamberlin]

P.s. I see now, that you have a Tenni, which will have the external fuel pump...and you are in Saudi! I am still voting for vapor lock to be the issue!

[Kiwi_Roy]

Can you be a bit more specific

 

The bike fails to crank?

or cranks but fails to fire?

when it cranks it fires ok?

 

I think on this model the start relay is powered through the ignition switch, that is a common problem quite easily fixed by removing the contact block and cleaning. The block is held on by 2 Phillips screws towards the rear (no need to remove the lock which is usually held by security bolts)

 

There is an interlock switch on the clutch lever, If you think its that just cut the wires off the switch and twist them together.

 

If you have a stand switch you can disable this by removing the stand relay and wrapping a bare wire figure 8 fashion around the central pins

 

    ___ 30     Short out 30, 67 & 87A

 

    ___ 87     

 

|      |     |

    87A 

 

Actually only one of the pins 87 or 87A is used but it's a no brainer to short all three, 30 is the hot one.

 

Since you are in the middle of a trip something easy is to jumper from the small solenoid trigger terminal to the battery or the large hot terminal bypassing all the start logic. Use a wire rated 10 Amps or more, the solenoid draws a lot of current.

[Orson]

Can you be a bit more specific

 

The bike fails to crank?

or cranks but fails to fire?

when it cranks it fires ok?

 .

Roy,

 

When hot, the bike failed to crank. An hour later after it had cooled off, it started right up.

 

Checked the battery connections mentioned by docc and they were tight.

 

In any case, I managed to finish the trip with one more failure to start but, fortunately I was on an incline and bump started it. When I arrived at the dealer and tried to show the problem, the bike performed perfectly!

 

The dealer thinks that maybe the starter motor might not be engaging. I can't remember when the starter motor was last replaced but, I think it might have been about 10,000 miles ago.

 

I'll let you know the outcome.

[Kiwi_Roy]

Fails to crank eh!

Do you hear the faint click of the relay?

If Not

Sometimes these bikes get a loose connection just under the tank, by wiggling the bars from lock to lock you find a sweet spot. Mine did that for a while then it cleared up so I never did find out exactly what was the cause, it's an electricians bike after all LOL.

 

If you hear the relay click but not the solenoids loud clunk its more likely to be a bad contact in the ignition switch, this is easy to clean.

The starter solenoid needs a super connection to the battery because it draws so much current. I'm not referring to the motor itself, that draws ~150 Amps, the solenoid on top has two coils, one draws 10 Amps but the other that does most of the work throwing the cogs into mesh would like to pull 40 - 50, just for a split second.

The Guzzi factory doesn't take that into account or they wouldn't keep wiring bikes in the same stupid way, I don't think they are aware of the second coil, if you look at the schematic in your manual it doesn't show it so nearly every model sooner or later suffers from what;s referred to as "Startus Interuptus".

My year of V11 Sport they wired completely different with the start relay powered directly from the battery as I show below. it never fails to crank if the batteries good and the start relay closes, however this wiring created other issues.

 

I wish I could speak to the engineers in the factory, if they took the time to listen It might save future owners a lot of grief.

I sometimes suggest to owners having start  problems, "add a little lamp to the starter solenoid trigger wire", I don't think anyone listens.

The lamp would just flash on when you press start to indicate how much Voltage the solenoid is getting, imagine how envious the Harley guys would be 

 

Next time it wont start eliminate all the wiring and prove the starter, battery and main connections are ok with a simple jumper a wire to the solenoids trigger terminal as I mentioned earlier.

 

 

In particular read Note 1

The funny looking diagram at the bottom of the page is what's known in electrical circles as a timing diagram used to describe the sequence of events. If you follow the second line across it jumps up to 50 Amps but quickly drops down to 10. The 50 Amp short pulse is when both coils are working hard to throw the gear into engagement and close the magnetic gap, as soon as they engage the main contacts close and the current bypasses the heavy coil, the light coil just has the easy job holding it in place while the bike cranks over.

 

This is a Valeo starter, the old Bosch starter solenoids work the same way. 

[Orson]

Roy,

 

Thanks for all the help. I could hear a electrical sounding click but, with ear plugs and helmet on, it was hard to make out if it came from the relays. It sounded as if it was coming from the engine so, maybe he was right about the starter motor not aligning?

 

Cheers!

[docc]

Clicking while activating the starter is a sign of low voltage. It is not, then, the bullet connectors for the clutch safety switch.

 

Just to be absolutely sure, tight battery terminals are critical, as is the connection of the ground to the gearbox. You are certain that ground connection to the gearbox case is well fettled?

[Orson]

Just to be absolutely sure, tight battery terminals are critical, as is the connection of the ground to the gearbox. You are certain that ground connection to the gearbox case is well fettled?

Well, I'm back at work in Saudi Arabia so, Am unable to check.

 

The bike gets to stay in Italy at Moto Guareschi while I toil away for another chance to ride. I'll update on findings by team Guareschi.

[luhbo]

Clicking while activating the starter is a sign of low voltage....

 

Basically not. It's a sign of low current, maybe due to low voltage. In fact in 9 out of 10 cases high resistance is the culprit. Keep that in mind when you dig through the schematics.

 

Hubert

[docc]

 This is a much more accurate statement, Hubert

 

Very interesting how closely this approach jibes with the electrical troubleshooting printed in How to Prepare the Sierra for Motorsport, compiled by Graham Robson for Ford, c.1988:

 

 

"The most common electrical faults in SIERRAs are caused by wiring faults i.e. breakage of wires or connectors, electrical shorting, poor or intermittent connections, or contamination by water or mud, rather than by component failure."

 

I have have found this so often true of the Guzzi, as well.

[docc]

 This is a much more accurate statement, Hubert

 

Very interesting how closely this approach jibes with the electrical troubleshooting printed in How to Prepare the Sierra for Motorsport, compiled by Graham Robson for Ford, c.1988:

 

 

"The most common electrical faults in SIERRAs are caused by wiring faults i.e. breakage of wires or connectors, electrical shorting, poor or intermittent connections, or contamination by water or mud, rather than by component failure."

 

I have have found this so often true of the Guzzi, as well.

It comes to mind that, here in the States, the (fabulous) Sierra was sold as the Merkur XR4Ti whose engine made a lot of vibration and makes me think that aspect is much like the Guzzi, as well, when it comes to points of possible failure in the electrical system.

 

Connections that were tight might jiggle loose . . .