New Stella 4-Stroke stalling - sporadic

Cellarrat · Post by **Cellarrat** » Sat Jun 22, 2013 11:39 pm

I've read a number of threads on the board and elsewhere that point to the evaporative emissions system canister being the culprit of many stalls - in combination with not having a vented gas cap.

I'm riding a new Stella 4T purchased in Santa Rosa CA still in the break in period so I'm not running anything full throttle. But now and then I find a situation where I'll ride for a while and park the bike for a bit, then I try to take off with a rider and I get two blocks and the thing stalls. (wait, ride for a few blocks, wait, ride for a few blocks...) I then park it with the gas cap lose for an hour, and when I go back to try an make it fail I ride 15 miles in pretty intense heat and it rides like a dream.

Then I come back to the house have a friend hop on the back and in two blocks the things craps out.

When I pulled the hose off the steel nipple on the Evap canister there was liquid gas in the hose.

I can't see any way the hoses of the evap system are getting pinched by extra weight. I think it's more likely the load on the engine. (and perhaps the added weight creates a more conducive situation for gas to enter the evap system. Where is the exit from the gas tank? form the back of the gas cap area?)

What is the most recent thinking on solving this common problem (admitting I have a odd add-on with the bike always failing with two people on the bike)
Thanks.

keith1295 · Post by **keith1295** » Sun Jun 23, 2013 3:46 pm

My scooter is having the same problem of stalling and total loss of power. I took it to the shop and they replaced the fuel tank and said the problem was fixed. So riding home it started sputtering and completely died again, so now it is back in the shop again....

gar1013 · Post by **gar1013** » Sun Jun 23, 2013 6:06 pm

The evap system has been known to cause people problems.

Your choices are to maybe fill the tank a bit less, OR... one could violate CA and Federal law by disconnecting the system.

If you go the latter route, I'd suggest that you not disclose who did it.

Cellarrat · Post by **Cellarrat** » Sun Jun 23, 2013 6:38 pm

Would disconnecting the Evap system cause a drop in gas mileage? Not that I'd do such a thing...

gar1013 · Post by **gar1013** » Sun Jun 23, 2013 7:52 pm

Cellarrat wrote:Would disconnecting the Evap system cause a drop in gas mileage? Not that I'd do such a thing...

Not per se. What it would do is allow gas vapors to be released into the atmosphere, based on my understanding.

So your fuel consumption wouldn't increase, but you would have a small quantity of fuel lost - similar to "the Angel's share" when it comes to whiskey while it's in the cask.

Spud · Post by **Spud** » Tue Jun 25, 2013 6:41 pm

keith1295 wrote:My scooter is having the same problem of stalling and total loss of power. I took it to the shop and they replaced the fuel tank and said the problem was fixed. So riding home it started sputtering and completely died again, so now it is back in the shop again....

That's appalling.

thewenz3 · Post by **thewenz3** » Fri Jun 28, 2013 2:27 pm

Please make sure to update this when you get it back. I have been having similar issues. My shop put in a more vented gas cap but the issue has not disappeared. A band-aid for the problem is to listen/feel for a 'low idle' (its not perky when you're sitting at a light) and then give it a small amount of gas. I use 'scoots' to commute and often in the morning it is not an issue; however on the way home yesterday it stalled once and wanted to stall quite a few more times.

Concerning the evap system, could you elaborate on the possible issue? Is it a hose being pinched. Is something overheating?

My other more broad question is:

What is the mechanism for causing the stall? Not enough gas to the engine?

Scoots is a Steela 2012 4T with ~1600 miles on it

Cellarrat · Post by **Cellarrat** » Fri Jun 28, 2013 5:24 pm

It sure feels like a fuel deprived system on my scoot. Going to dig back into the issue now that I'm back home with decent weather. Going to be hotter then hell this weekend though.

No pinched hoses, no other physical blockage other than liquid gas in the evap system, rather than vapors. I have not taken apart the evap system to see if there is residual liquid blocking the venting but that is my suspicion.

Will update

Spiffy · Post by **Spiffy** » Wed Jul 10, 2013 6:23 pm

sounds like gas entering the evap system... the weight of the extra passenger makes the rear sag just enough that the gas is now splashing up there...

I put in a one-way valve so gas/vapor can only flow INTO the tank and I installed a 2T vented gas cap... problem solved...

thewenz3 · Post by **thewenz3** » Wed Jul 10, 2013 6:30 pm

@Spiffy

I have found that holding in the clutch makes a difference on the air system? When I am in true neutral with the clutch out I experience no stalling, but if I'm in first gear with the clutch in, it will stall.

Currently I sit at lights in neutral and switch into first when the light turns; however this causes me to mistake which gear I'm in occasionally and stall out. Otherwise this would be a non-issue.

Could you provide information on the 1-way valve you used?

gar1013 · Post by **gar1013** » Wed Jul 10, 2013 7:55 pm

thewenz3 wrote:When I am in true neutral with the clutch out I experience no stalling, but if I'm in first gear with the clutch in, it will stall.

That almost sounds as if your clutch needs adjusting.

Cellarrat · Post by **Cellarrat** » Wed Jul 10, 2013 8:18 pm

I pulled the hose coming off the nipple of the evap unit and put 150 miles on without a hickup. Well over 100 deg weather also. But the second I get a passenger on I lose power in a block. Even with a low tank and that hose disconnected.

I'm also curious to hear about the one-way valve. Is this system gravity driven or is there some pressure involved?

Thanks

gar1013 · Post by **gar1013** » Wed Jul 10, 2013 9:01 pm

Hmm... I wonder if somehow you're disrupting the flow of fuel when you add the passenger.

What are your combined weights (with gear, etc)?

Cellarrat · Post by **Cellarrat** » Wed Jul 10, 2013 9:17 pm

It's very strange. Combined weight would be 285-ish. I've looked at everything and with the hose pulled we shouldn't be able to restrict the flow since evap is out of the system. I've got a 2t vented gas cap coming and will fully isolate the Evap system to rule it out. I wonder if they are working on a fix.

Robbie · Post by **Robbie** » Wed Jul 10, 2013 11:31 pm

Cellarat,
Remove the engine side cowl and follow the fuel line from the carburetor to the tank outlet.
Based on your description, the line is too long and there is a kink.
As the day gets warmer and undercowl temps. get higher, the kink will tend to close the hose.
It will be worse with a passenger (sound familiar?) because the engine is pushed even higher up (oe the body down) further closing the fuel line at the kink point.
There have been many many 4t's experiencing this.

Good luck,
Rob

Cellarrat · Post by **Cellarrat** » Thu Jul 11, 2013 12:48 am

Robbie, you are frickin' awesome. I just pulled the cowl, and yes the hose seemed to have a fairly sharp turn in it. all I did was grab the hanger that aims the fuel line and pushed it up so that the hose could not kink when compressed. Grabbed my girl and just did a 10 block loop with no problems.
I might still shorten the line but for now, we're good to take rides.
Thanks so much

Alan

Spiffy · Post by **Spiffy** » Fri Jul 12, 2013 5:04 pm

thewenz3 wrote:Could you provide information on the 1-way valve you used?

I used this one... even though it's a vacuum valve it still works ok there...

here's a picture...

Modern Buddy

New Stella 4-Stroke stalling - sporadic

New Stella 4-Stroke stalling - sporadic

Evap...

Re: Evap...

evap etc

passenger