Start issue creeping in

[Gmc28]

Not a serious issue yet, but chewing on why in the last month or so red (2002 lemans) will now sometimes fire up, idle just a little, stumble, and then quit.  If its in that mood, I’ll have to do that about 5 times before i can carefully blip the throttle and get her to finally catch.  Most of the time its biz as usual, firing off right away, hot, cold, or in between, no problem.  But about every 5th start, and often two starts in a row on a given day, it will fire-off, stumble, then quit (and repeat).  Can happen after sitting for a couple weeks, or just sitting for a few hours between rides. 

If i had carbs I know where I’d be looking, but am  noodling what the issue here would most likely be.  She’ll get the usual winter go-through in a couple months, but thought I’d float it to see what obvious thing I’m missing…. 

Cheers

[docc]

First four of “the usual suspects “ (which you may have already addressed, yet some bear revisiting periodically):

1) Clean, tight, sealed battery terminals. 2) Clean, treated, inspected Ignition Switch. 3) OMRON G8HE High Current relays in tight, clean bases. 4) Decent Tune-up.

There, of course, “others” . . .

 

[Gmc28]

Thanks Docc, but this isn’t electrical, it’s presumably a fuel feed issue, or something along those lines.  She cranks and initially fires just fine, but then if you try and blip the throttle it quits, and if you leave it alone it quits. Almost like the idle is set too low, but then next day and next several days its back to normal.  

[paulnaz]

 Me thinks you may have the beginnings of a dead spot or corrosion in your TPS.  Guzzi Diag can help with this, also check your CO settings.  Of course it could be a bad slug of gas.

 

      Paul B

[Kiwi_Roy]

As Docc says I would suspect the ignition switch, when's the last time you cleaned the contacts?

If you wire a small lamp to the petcock fuse F8 you may see it go dim or flicker confirming that there is a bad contact somewhere between the ignition switch, kill switch or side stand relay.

[p6x]

Each time I start the (cold) Le Mans 2004, I use the "choke" control described in the user's manual 2002 issue.

I set it to the full starting position, crank the tractor to get it started without touching the throttle. I let it run with the choke until the engine starts to accelerate and I slowly back up the choke to keep the same rpm.

Successive starts, I crack open the throttle just a little bit before I crank the engine.

So far, the John Deere never failed to start at first solicitation.

 

[Kiwi_Roy]

What does the John Deere have to do with anything?

[Gmc28]

On 9/8/2021 at 7:53 AM, p6x said:

Each time I start the (cold) Le Mans 2004, I use the "choke" control described in the user's manual 2002 issue.

I set it to the full starting position, crank the tractor to get it started without touching the throttle. I let it run with the choke until the engine starts to accelerate and I slowly back up the choke to keep the same rpm.

Successive starts, I crack open the throttle just a little bit before I crank the engine.

So far, the John Deere never failed to start at first solicitation.

 

That describes how i do it on both the V11’s, and works a charm.  And usually on first attempt it will run on the “choke” for a little until i hear it accelerate a smidge then i can blip throttle, just as you’ve described, though sometimes it takes a 2nd attempt.  Same thing now, but it might take 5 attempts, as i wait for that “acceleration” without touching throttle, but it doesn’t happen, and just quits after a few seconds (or if i blip throttle too early, it also quits).

I feel like I’m making more of this than necessary, and once i get her into the shop this winter and just look things over it may be all fine, but it is still an interesting question.  Again, not electrical insofar as relays and start switches, as all that works fine.  The TPS idea seems a possibility, and i suppose my CO could have drifted from the “perfect” setting i had it at last winter, so i can check all that out easy enough once the rains come and she’s in the shop for the winter (she runs well enough to not waste the precious seasonal weather to do anything but ride).

cheers 

[docc]

Sounding worthwhile to re-perform a Decent Tune-up with particular attention to the TPS. While I've never heard of, or seen, the CO Fuel Trim "drift", the TPS certainly can.

Not unlikely, the issue is a matter of "stacked tolerances" as several parameters have developed slight contributions that add together.

[p6x]

There is something we have possibly discounted as a major factor.

Here in Texas, you start your day with temperatures close to 80 degF. And substantial humidity. Only now have the temperatures slightly been cooler (in the morning).

The International Harvester sleeps in the garage, which is always quite warm. How much those parameters affect the mixture density and combustion? so maybe comparing Nashville and H'town does not really tell much.

[Gmc28]

I would tend agree Docc that its just a matter of my girl needing a little attention (she’s a selfish girl sometimes….), and perhaps its less about a single flaw and more about getting things all lined up properly.  And you got me on the CO ‘drift”…. You’re right, that’s not a wear-and-tear thing… touché, i just got too loose with my postulating.  Get a few drinks it me and it’ll get even looser… we’ll be talking MG fetzer valves and framostats in no time. 

And P6x, are you implying i should replace the glow plugs on my Guzzi?      I like the tractor analogy!  In all seriousness, i certainly agree that some temp/humidity combo effects how she runs, where some days they will run perfectly with no burbles or flat spots while other (usually hotter) days little hiccups are apparent, but starting has always been about the same on the guzzi’s, as they’re almost freakishly reliable in how they start, all 3 of them, in all weather, whether they’ve been run the day before or sitting all winter.  In that way, they are like my diesel machines (though maybe your IH and Deere are gas?  ). 

[p6x]

On 9/17/2021 at 9:27 AM, Gmc28 said:

I would tend agree Docc that its just a matter of my girl needing a little attention (she’s a selfish girl sometimes….), and perhaps its less about a single flaw and more about getting things all lined up properly.  And you got me on the CO ‘drift”…. You’re right, that’s not a wear-and-tear thing… touché, i just got too loose with my postulating.  Get a few drinks it me and it’ll get even looser… we’ll be talking MG fetzer valves and framostats in no time. 

And P6x, are you implying i should replace the glow plugs on my Guzzi?      I like the tractor analogy!  In all seriousness, i certainly agree that some temp/humidity combo effects how she runs, where some days they will run perfectly with no burbles or flat spots while other (usually hotter) days little hiccups are apparent, but starting has always been about the same on the guzzi’s, as they’re almost freakishly reliable in how they start, all 3 of them, in all weather, whether they’ve been run the day before or sitting all winter.  In that way, they are like my diesel machines (though maybe your IH and Deere are gas?  ). 

Well, I also need to slightly alter my starting procedure.

The best result is achieved when you crack open the throttle AFTER you start cranking. Warm engine procedure; start with closed throttle, and open a tad while cranking.

As for the "tractor" association, it goes back to 1976. I was in the army, and the extreme drought affected animal feed. My regiment was seconded to farmers to harvest hay that could be sent to those that did not have any pasture for their cows.

We got distributed to farms, and helped loading hay on trailers tractor pulled. This is when I discovered that being a farmer had two major advantages:

-they seem to always have wine available throughout the day.

-farmer girls know their way around hay in more ways than one would initially think....

Both above perks helped with the amount of blisters I got from using a pitching fork....

[Gmc28]

Wine on a farm, in Texas?  Sounds like a twighlight zone episode.  Cheap beer for dinner was the highlight of our day (evening) in the summer farm season up here.  But at that age I would have treated all those beverage options the same….  Homer Simpson style. 

[Gmc28]

Variation on the same thread topic:

went out today to do other stuff in the shop, and thought I’d fire up Goldie, since she might get used next week of my amigo wants to do a ride out to eastern Oregon.  Bike used to be his, and he’s supposed to buy it back, but it’s been sitting here now for over a year unused (I ride red instead, stablemate).

key on, relays click, but no fuel pump sound.  Cranks strong, no start.  Fuses and relays ok upon quick inspection (pull, quick inspect, replace). Have to circle back to this so I can get other stuff done today, but refresher from anyone on typical culprits for no fuel pump action?  Failed pump of course could be it, but other common connection issues that might be at fault?

[footgoose]

swap relay 5