Stella Automatics - Problems with the ECU

Elder Scoot · Post by **Elder Scoot** » Thu May 22, 2014 2:59 pm

The Stella automatic features an ECU (Electronic Control Unit) made by Del Orto. The Unit gets data from an oxygen sensor and throttle position sensor and as the engine runs and demands are made on it the ECU takes readings from the various sensors and varies the amount of air coming into the carburetor.

On the two Stella automatics I have owned the dealer had to replace the ECU unit found on the right side of the bike near the gas tank. The bikes were not producing a spark and in this case the Del Orto ECU likely controls the capacitive-discharge ignition system

In both cases the dealer changed out the ECU with a new one (under warranty). It is a one bolt, 5 minute, easy process and each time afterwards the bikes fired right up and were running better than before.

Given how much of the bike is controlled by that unit if you have a running problem -- and you are getting gasoline into the carb, it is likely the ECU that is not working. No gas can mean a fuel pump issue, a fuel line issue or out of fuel.

It's a great bike and I hope Genuine, LML and Del Orto can sort this one out.

BeefSupreme · Post by **BeefSupreme** » Thu May 22, 2014 3:57 pm

I remember reading about similar issues on the Auto's last year when I was thinking about one on the LML owners forum in GB. They've had the autos for a while longer so maybe some of their discussion will be helpful.

http://www.lmlocgb.co.uk/phpBB3/viewforum.php?f=29

Elder Scoot · Post by **Elder Scoot** » Thu May 22, 2014 4:09 pm

BeefSupreme wrote:I remember reading about similar issues on the Auto's last year when I was thinking about one on the LML owners forum in GB. They've had the autos for a while longer so maybe some of their discussion will be helpful.

http://www.lmlocgb.co.uk/phpBB3/viewforum.php?f=29

I believe that the British LMLs have their version of the ECU made by Keihin. The big issue they were having had to do with the sensor on the Keihin ECU being too sensitive. Why Genuine would choose Del Orto if a Keihin unit available is beyond me - unless of course - the Del Orto was cheaper.

Tipper · Post by **Tipper** » Thu May 22, 2014 6:49 pm

Elder Scoot wrote:
BeefSupreme wrote:I remember reading about similar issues on the Auto's last year when I was thinking about one on the LML owners forum in GB. They've had the autos for a while longer so maybe some of their discussion will be helpful.

http://www.lmlocgb.co.uk/phpBB3/viewforum.php?f=29
I believe that the British LMLs have their version of the ECU made by Keihin. The big issue they were having had to do with the sensor on the Keihin ECU being too sensitive. Why Genuine would choose Del Orto if a Keihin unit available is beyond me - unless of course - the Del Orto was cheaper.

The UK spec autos also have the Delortto ECU's. Trust me if anyone was going to cut corners to save money it would be Moto GB the UK importer. You guys are lucky to have Genuine.

Elder Scoot · Post by **Elder Scoot** » Thu May 22, 2014 7:37 pm

Tipper wrote: The UK spec autos also have the Delortto ECU's. Trust me if anyone was going to cut corners to save money it would be Moto GB the UK importer. You guys are lucky to have Genuine.

Tipper, I copied this from the LML Forum. It's a post supposedly from LML:

"The Dellorto Electronic Carb designed for Euro 4 emissions (not needed yet) has caused some issues in this installation, SYM are fitting it to the new SYM Fiddle III as an option, we have NOT chosen the Dellorto and have gone with a Keihin for now!!!

The warning light is indicating that the emissions have exceeded the parameters for Euro 4 and the frequency of the flash relates to the problematic sensor. The scooter runs flawlessly (orange indicator means 'advisory', a red indicator is warning of impending doom!)

One of the sensors is located at the end of a pipe coming from the carb, if this sometimes short pipe fractures then the ECU tells the carburettor to alter mixture to a degree that does cause a running problem..... it over fuels and bogs down. Block this pipe and hey presto your Auto runs fine!

The advice to buy from a dealer with a reputation is valid, Scooter Moda are superb, so too is Motoretta. There are a good few 'Gem' dealers out there.....

Cheers
LMLUK"

Tipper · Post by **Tipper** » Thu May 22, 2014 9:43 pm

Oh yeh sorry ! I was thinking of that post and thought it was the other way round.

I know the auto that scootering magazine tested had the delortto ecu fitted because they mentioned it a couple of times.

I wonder why they made the switch ?

Seems like both systems have issues.

caffeine65 · Post by **caffeine65** » Fri May 23, 2014 12:24 am

It's funny, I just began having trouble with my Stella Auto today, and I think this may be the issue. Glad it's not serious.

ElderScoot, what were the symptoms that prompted you to head to the dealer? For me, the bike is stalling under acceleration, and there's a definite flat spot in the throttle. On the centerstand, the bike struggles to idle.

Hope my dealer hasn't started his Memorial Day weekend yet!

Dooglas · Post by **Dooglas** » Fri May 23, 2014 1:12 am

Just thinking out loud as I am hardly an expert on vehicle electronics or that kind of stuff. Several models of fuel injected Vespa/Piaggio have had issues concerning idling, acceleration, fuel consumption, what-have-you that has been traced back to "mapping" of the ECU (i.e. it's programing). Sometimes that has been resolved by reloading the original mapping, sometimes it has been resolved by the manufacturer issuing an update to the mapping. Darned if I know how you separate "mapping" problems from electromechanical problems with the ECU itself however.

Elder Scoot · Post by **Elder Scoot** » Fri May 23, 2014 1:26 am

Tipper wrote:Oh yeh sorry ! I was thinking of that post and thought it was the other way round.

I know the auto that scootering magazine tested had the delortto ecu fitted because they mentioned it a couple of times.

I wonder why they made the switch ?

Seems like both systems have issues.

Tipper,

I read the early Star 125 reviews and they also mentioned the bike having a Del Orto carb. Honestly I don't know what to think.

It seems that the problem the LMLs in the U.K. were having was with a light indicating a problem with the ECU whereas we are having problems with the motors not starting or dying.

I'll take the light if I had a choice.

Elder Scoot · Post by **Elder Scoot** » Fri May 23, 2014 1:31 am

caffeine65 wrote:It's funny, I just began having trouble with my Stella Auto today, and I think this may be the issue. Glad it's not serious.

ElderScoot, what were the symptoms that prompted you to head to the dealer? For me, the bike is stalling under acceleration, and there's a definite flat spot in the throttle. On the centerstand, the bike struggles to idle.

Hope my dealer hasn't started his Memorial Day weekend yet!

My first Stella 125 just wouldn't start. Period. With a new ECU it fired right up. My second Stella pulled strongly for 200 miles then died and would not start. In each instance I removed the gas cap and saw gas being sprayed into the carb. So the issue is with ignition. My hunch is that the there is a weakness or crack in the internals that expand with heat and lose contact. Some coils do that.

Elder Scoot · Post by **Elder Scoot** » Fri May 23, 2014 1:36 am

Dooglas wrote:Just thinking out loud as I am hardly an expert on vehicle electronics or that kind of stuff. Several models of fuel injected Vespa/Piaggio have had issues concerning idling, acceleration, fuel consumption, what-have-you that has been traced back to "mapping" of the ECU (i.e. it's programing). Sometimes that has been resolved by reloading the original mapping, sometimes it has been resolved by the manufacturer issuing an update to the mapping. Darned if I know how you separate "mapping" problems from electromechanical problems with the ECU itself however.

Howdy Dooglas - I'm "Oldscoot" on MV - that name was already taken on this forum. I don't think my dealer has a computer other than the one they use for e-mails much less a device for re-mapping the Stella ECU. I've got a hunch this is mechanical brought on by vibration and/or heat. It's just a hunch however.

StellaFelL.A. · Post by **StellaFelL.A.** » Fri May 23, 2014 8:25 pm

On mine the ECS light comes on and flashes sometimes. Also when I'm riding it slightly hesitates for a second about once or twice on each ride. I wonder if the hesitation is part of the break-in period or could it be something else. My 310 miles first service is coming up soon and I'll let the dealer know about these issues.

Elder Scoot · Post by **Elder Scoot** » Fri May 23, 2014 9:06 pm

StellaFelL.A. wrote:On mine the ECS light comes on and flashes sometimes. Also when I'm riding it slightly hesitates for a second about once or twice on each ride. I wonder if the hesitation is part of the break-in period or could it be something else. My 310 miles first service is coming up soon and I'll let the dealer know about these issues.

The ECU light issue (at least as it has been fleshed out in Europe) is not a real problem but relates to the fact that the ECU is programmed for a higher restrictions than are the current requirement.

The hesitation issue is something to be looked into.

StellaFelL.A. · Post by **StellaFelL.A.** » Sat May 24, 2014 1:19 am

Thanks for the reply elder. I'll see what the dealer finds out and report back.

az_slynch · Post by **az_slynch** » Mon May 26, 2014 5:04 am

Silly idea perhaps, but I wonder if the throttle position sensor works like one from an EFI engine. I know that you can reset it on some scooters by switching off the ignition, rolling the throttle open and holding it , switching on ( but not starting) the scooter and keeping the throttle open until the light on the dash goes off ( ECS instead of a CEL), switching the scooter off and closing the throttle.

I've done that with my Yager when it would hesitate on throttle opening and it seems to clear it up. Now, swapping to a high-flow air filter required a battery disconnect to reset the ECU fuel map back to default, but I suspect that step is unnecessary for any carbureted scooter.

caffeine65 · Post by **caffeine65** » Thu May 29, 2014 2:13 pm

I wanted to add to this thread that, in my case, my troubles seem to have cleared up, and that I may have been experiencing vapor lock.

Here's the thing- the day my Stella started acting strange, I'd just returned from vacation, so the bike had been sitting for 6 days. I fired it up for a quick ride and immediately had issues.

Being new to scooters, I didn't think sitting in the garage without being run should matter, and it probably doesn't. However, in fiddling with it to try and figure out what's wrong, I had at some point removed the gas cap, and was surprised at how much pressure had built up in the tank. That cap must have zero ventilation!

And guess what... Although I didn't make the connection at the time, the bike mysteriously ran better after that, and now seems to be back to normal, with no more stalling and no flat spot in the throttle.

I'm hesitant to give it an "all clear" and I'll definitely give the dealer the details when I take it in for service in a week or so. But for now, knock on wood, no issues in sight.

KABarash · Post by **KABarash** » Thu May 29, 2014 3:39 pm

caffeine65
So you're suggesting the 'dreaded vapor lock' has manifested itself in the 'stellautos'?
There's been lots and lots and lots of discussion about that here over the years.
Try riding with your gas cap a little loose, if that eliminates the perceived problem you should be able to get a vented cap or drill your existing cap to vent it.

caffeine65 · Post by **caffeine65** » Thu May 29, 2014 4:39 pm

KABarash wrote:caffeine65
So you're suggesting the 'dreaded vapor lock' has manifested itself in the 'stellautos'?
There's been lots and lots and lots of discussion about that here over the years.
Try riding with your gas cap a little loose, if that eliminates the perceived problem you should be able to get a vented cap or drill your existing cap to vent it.

Please don't take my word for it. I'm only a shade tree mechanic at best. But after reading some of the other threads, and remembering the absurd amount of pressure released from the tank, I'm just taking an optimistic guess.

Like I said, I'll see what the dealer thinks, and perhaps take a drill to the cap after that. EDIT... And of course report back!

Elder Scoot · Post by **Elder Scoot** » Thu May 29, 2014 4:51 pm

caffeine65 wrote:I wanted to add to this thread that, in my case, my troubles seem to have cleared up, and that I may have been experiencing vapor lock.

Here's the thing- the day my Stella started acting strange, I'd just returned from vacation, so the bike had been sitting for 6 days. I fired it up for a quick ride and immediately had issues.

Being new to scooters, I didn't think sitting in the garage without being run should matter, and it probably doesn't. However, in fiddling with it to try and figure out what's wrong, I had at some point removed the gas cap, and was surprised at how much pressure had built up in the tank. That cap must have zero ventilation!

And guess what... Although I didn't make the connection at the time, the bike mysteriously ran better after that, and now seems to be back to normal, with no more stalling and no flat spot in the throttle.

I'm hesitant to give it an "all clear" and I'll definitely give the dealer the details when I take it in for service in a week or so. But for now, knock on wood, no issues in sight.

My issues were with the first bike not starting at all - and the second bike dying and not restarting. In both instances the gas cap was removed to see if the carb was getting fuel at all - and it was. Removal of the cap did nothing to remedy the problem. In both instances a new ECU cured the problem.

You may be experiencing something else. That cap is screwed on very tight. I hope your issues are solved. Keep us posted.

caffeine65 · Post by **caffeine65** » Sat May 31, 2014 1:31 pm

Elder Scoot wrote:My issues were with the first bike not starting at all - and the second bike dying and not restarting. In both instances the gas cap was removed to see if the carb was getting fuel at all - and it was. Removal of the cap did nothing to remedy the problem. In both instances a new ECU cured the problem.

You may be experiencing something else. That cap is screwed on very tight. I hope your issues are solved. Keep us posted.

It's great that your troubles were resolved with such finality! I'm hoping for the same peace of mind. Will definitely let you guys know what the dealer thinks (if he can determine anything at all, considering the bike runs fine now).

caffeine65 · Post by **caffeine65** » Sun Jun 08, 2014 12:53 pm

Ok so I can rule out vapor lock in my case, since the problems eventually returned despite my efforts to keep pressure from building in the fuel tank.

This weekend, I took the bike in for 300-mile servicing, and the dealer replaced the ECU and gave it a clean bill of health.

Once again, the bike is running fine, but my confidence in it has taken a serious hit.

You know that saying, waiting for the other shoe to drop? Only this is more like waiting for the same shoe to drop again, lol.

We'll see!

Elder Scoot · Post by **Elder Scoot** » Sun Jun 08, 2014 1:12 pm

caffeine65 wrote:Ok so I can rule out vapor lock in my case, since the problems eventually returned despite my efforts to keep pressure from building in the fuel tank.

This weekend, I took the bike in for 300-mile servicing, and the dealer replaced the ECU and gave it a clean bill of health.

Once again, the bike is running fine, but my confidence in it has taken a serious hit. You know that saying, waiting for the other shoe to drop? Only this is more like waiting for the same shoe to drop again, lol.

We'll see!

I had the same feeling after replacing my ECU. Genuine tells my dealer that the new ECUs do not have the same problem as the earlier run. Vespa had a serious fuel pump issue with certain of the early GTI bikes and that was corrected. I've read the ECUs on our bikes are manufactured in Japan and that this Del Orto set up has been used for years.

Genuine will have to address the issue.

jimmbomb · Post by **jimmbomb** » Sun Jun 08, 2014 4:00 pm

Ive heard talk about "drilling your existing gas cap" in this thread and a few others.
Id like to see a "DIY" on just how to do this, and where to put the hole.
how deep, etc
thanks

Dooglas · Post by **Dooglas** » Sun Jun 08, 2014 6:13 pm

jimmbomb wrote:Ive heard talk about "drilling your existing gas cap" in this thread and a few others. I'd like to see a "DIY" on just how to do this, and where to put the hole. how deep, etc

That is a fix for the "vapor lock" issue which occurred on some earlier bikes. It is really a tank venting issue. You can easily test for it by loosening your fuel cap. If your problem goes away - then you likely have a tank venting issue. If it doesn't - you don't

. If you do, vented caps can be purchased or you can put a small vent hole in your cap with an 1/8 inch drill. There have been several previous discussions of this in the General Discussion section.