Original owner finds a *sputter*

[Chuck]

Quote

I have heard that decomposing fuel lines can also create internal flaps that will act like valves to restrict fluid flow. Not seen that myself, but worth considering.

That's a fact, and I've seen it. During the annual inspection of an aircraft, one of the things you do is remove the fuel line from the gascolator to the carb and carefully look through it.

[Tomchri]

Put a meter on to check the fuelpressure, small plumbing job with parts from a hydraulic store. Charging is good,,, so so or may be get a Mosfet regulator,,, NO more 30amp trouble.  Have you Checked your RPM sensor, I had my share of RPM sensor trouble, little smell here,,, easy to Ohm.  550 - 700 Ohm cold, varm = zero.  Plug wires easy to Ohm to,  around 5000 Ohm, just the wires. Just some thoughts here.

Cheers tom.

[Bbennett]

2 hours ago, docc said:

ORIGINAL POSTER REPLIES IN CAPS.

  1)  Fuel is tapped from the left lobe through the petcock. Your manual petcock is visible in your first picture and the knurled knob on its bottom should be turned fully on (counterclockwise looking up at it from below). Make sure your left side petcock fully open  (counterclockwise). These directions are as if you are looking up at the petcock, so the arrow direction in your image looks correct, but worth verifying.
YES VERIFIED

  2) I am having trouble understanding what you mean by "the rod on the right side."  What is pictured in your second image is the regulator with the fuel line that returns unused fuel to the right (trap) lobe and should not be turned. Can you clarify what you turned on the right side?  SEE ANNOTATED IMAGE BELOW FOR ROD/TILLER

Please clarify what "position" the rod/tiller should be in.....thank you

[Rox Lemans]

2 hours ago, Bbennett said:

OK, after replacing the fuel I did a test ride today and the sputter is not fixed. 

Symptoms:  The bike will start fine.  It will run OK for about 30 seconds after which there is a gurgling (underwater sound) sputter / misfire that occurs first at 2000 RPM and then seconds later at 1500 RPM and finally the bike if left to idle will die after about 3 seconds.  This does not require load - is repeatable in neutral.  Bike will start and show same symptoms (idles fine at 1st etc.) after 5 minutes rest.
 

Bike history: Always been a strong runner, has approx 60K miles and is ridden at least every 2 weeks.  Bike has always had a weak elec system, I have replaced regulator 3-4X over 20 year period.  Bike suffers from a parasitic elec leak, I have to put it on charger before a ride if it has not been ridden the day before.   This has resulted in long periods of the bike being on a charger.  Bike has always had a rough spot at 2800 RPM - never could fix it.  The 2800 stutter is exacerbated by hot weather but I can typically throttle "thru it."  Minor note: Temp shielding on fuel lines to avoid fuel boil has had no effect on temp stutter.

What I have checked / recently touched:

a. Bike exhibited the sputter for 1st time week ago when Reserve Light was indicating low fuel level.  This was at 60 MPH / 4K RPM.
b. Adding fuel allowed bike to get home fine (approx 3 miles).
c. 3 days ago fuel tank drained*, new fuel (from working Honda bike) added.  I was careful to get fuel into both lobes of tank - me not being sure which side sucks the fuel. Still, the fuel tank is not full.  I would estimate there is only 3/4 of a gallon in the bike.
d. *When tank was drained it was removed.  Upon installation of the tank I turned the rod on right side all the way counterclockwise (see pic).  The knob on the left is fully turned clockwise.  ***Is this correct?***  Elec connectors were mated under tank as per usual. 
e. Bike started fine after fuel tank installation w/ pint of fuel.  Fuel reserve light was not lit (but it is unreliable). 
f. With 3 addit. quarts of fuel added, a test drive --in warm but not hot hot weather --showed symptoms above.  This stutter is far worse than the temperature stutter noted in history section.  LED showing battery level showed the battery was near fully charged during test.
g. 6 months ago I replaced main battery cable with new, super conducting 3rd party cable.  Prob has 500 miles on it - no issues.  Fuse on new cable is intact.
h. Main Guzzi fuse box today revealed a burnt 30 amp fuse.  I replaced the fuse but symptoms continued.  A 20 amp fuse was replaced with the correct 15 amp fuse.  No effect.
i. One of the battery terminal screws was not fully tight.  When tightened, symptoms remained.
j. Spark plugs changed 100 miles ago.  Spark plug wires have not been replaced for over a dozen years.
k. No change in exhaust smoke noted (exhaust not visible).

<pics below>

Thanks for your advice

Bob

 

p.s. Air filters removed for pix

 

 

 

 

 

Is this while riding after a while in hot weather? Kinda sounds like the infamous vapor issue. Sputtering? Stalls?  Gurgle sound? Bike sits for a while then starts fine? Sounds like it.. Your burnt fuse may be a different issue. 

 

Mine was doing it in this 115 degree heat. Also a valve cove gasket seep (heat stuff). Heat shielding the fuel lines and fuel pump. Plus a new gasket. Should be golden. 

[Rox Lemans]

Oh, and your petcock is fine. 

 

The 30 amp? Had to think about it.. Sounds like one of my rookie mistakes. Trying to start it letting the starter run maybe? Or the battery may be low. 

I've done it. Almost threw my helmet once when it happened.. These are new Guzzi owner issues. Easily sorted out. 

[docc]

2 minutes ago, Bbennett said:

Please clarify what "position" the rod/tiller should be in.....thank you

So, that is the regulator. It should remain stationary (no adjustment). The "rod" (circled in green) is open to atmosphere and is typically oriented facing forward.

These things don't sound like the issue. Interesting comments about fuel line failures. Maybe even fuel filter? Or fuel pump failure?

No way it could be an under-rated relay failing in Position #5?

 

[Bbennett]

It could be the heat issue.... but it is not that hot and usually my bike has to be ridden fairly hard for at least 10 minutes for it to manifest.  These symptoms are also more severe and occur within a minute of starting bike.  The heat issues tend to occur only at low speeds.  BTW, I have heat shielded my fuel lines (but not fuel pump) - had no effect that I could sense.

A blocked fuel line that allows only a trickle of fuel could also explain behavior (fuel line on left side is only 2 years old but I will check it if nobody comes up with an "aha" observation).  The trickle would result in enough fuel "after some time" but starve the bike in actual operation.

Bob

[Rox Lemans]

2 minutes ago, docc said:

So, that is the regulator. It should remain stationary (no adjustment). The "rod" (circled in green) is open to atmosphere and is typically oriented facing forward.

These things don't sound like the issue. Interesting comments about fuel line failures. Maybe even fuel filter? Or fuel pump failure?

No way it could be an under-rated relay failing in Position #5?

 

My bad. That's what I meant. Good save, Sir. 

[Scud]

13 minutes ago, Bbennett said:

A blocked fuel line that allows only a trickle of fuel could also explain behavior (fuel line on left side is only 2 years old but I will check it if nobody comes up with an "aha" observation).  The trickle would result in enough fuel "after some time" but starve the bike in actual operation.

Blockage could be in any line as it makes a big loop: Petcock to Pump, to filter, to LH Injector, to RH Injector, to Pressure Regulator.

When I had my problem, I took off the pump and it tested fine. Then I reconnected it to the blocked fuel lines... it drove me crazy for a long time till I finally solved it.

[docc]

11 minutes ago, Scud said:

Blockage could be in any line as it makes a big loop: Petcock to Pump, to filter, to LH Injector, to RH Injector, to Pressure Regulator.

When I had my problem, I took off the pump and it tested fine. Then I reconnected it to the blocked fuel lines... it drove me crazy for a long time till I finally solved it.

It is always good to know what makes one crazy.

Sometimes, people are crazy and no one knows why . . .

[docc]

@Bbennett, what is the status of the relays on your Sport?

I ask because the V11 Relay #5 has to carry 22.5  amps, continuous, to the fuel pump, injectors, and coils.

Under-rated relays (20 amp NO) get hot and fail. This shows up, then, as a "heat related" fuel and ignition failure.

(I would still make sure there is more than 3/4 gallon of fuel in that tank. A couple gallons and try again . . .)

[hammershaug]

15 hours ago, Bbennett said:

h. Main Guzzi fuse box today revealed a burnt 30 amp fuse.  I replaced the fuse but symptoms continued.  A 20 amp fuse was replaced with the correct 15 amp fuse.  No effect.

Please beware of the 30A charging circuit. I've been there...

The black ground wire on the voltage regulator bracket is very thin and has too high resistance. If you happen to have a bad main grounding, the charging current may travel back in this wire. Worst case scenario: smoked cable harness and a lot of work.

I don't know much, but my advice is to add a better regulator grounding and check all your connections. Even better; replace the original regulator with a directly connected one that not relies on relays to work. 

 

 

[Bbennett]

**Resolved**

I am happy and mildly embarrassed to report that adding a bit more FUEL to the fully drained tank fixed the sputter.  I will never know if the "original" sputter was due to old bilge fuel in the lower reaches of the tank.  But that latest sputter was absolutely the result of a low fuel condition.  Thank you to Docc and all the rest of you for your advice -- some of which I plan to add to my "to do" list for the bike.

 

 

[hammershaug]

Great news! Wow, that's a black beauty. Take good care of her.