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Discussion Starter #1
I'm going to try this again... hopefully someone has a bit of experience with this and can point me in the right direction..

As I've said before... I have a stalling problem with my 03 AN400..

after taking it to the local dealership and spending over $100 to fix the problem.. the problem still exists..

my issues are as follows...

my scooter will start to stall out at idle once to temperature... After taking my scooter back to the dealership to advise them they didn't fix the problem (the stalling was happening and i took it straight to them to experience)... the best they could come with with is throw another spark plug in and see what happens.. now, i took the scooter back to them with less than 100 miles since they "fixed" it and the plug appeared to be carbonized... more so than should happen with less than 100 miles.. after talking with my ASE certified car mechanic.. he said the unit is running rich.. so rich, its stalling it out.. Great I say.. but where do i go from there... he mentioned looking at the oxygen sensor.. the temperature sensor.. maybe even the MAP or MAF sensors.. all great suggestions...

BUT.... there's always a but... the twist to this whole issue is rain... normally when the unit stalls out, it restarts without an issue.. however, when you throw rain into the equation.. it appears i now have an electrical issue.. because if i get caught in rain... it won't restart until the next day.. probably after everything has dried off completely...

so... if anyone knows of a direction i can take... or has had similar experience, i sure would appreciate any help..

also.. if anyone who reads this is familiar with milwaukee, wi.. i would love to hear of an reputable aftermarket shop to take it to.. i have a feeling this electrical issue may kick my butt...

thanks again..
 

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Discussion Starter #3
as for if the choke is open or closed, i don't know how to check that

as for running.. when "driving" it runs like a dream, i only have the issues at a stop sign or as i may be slowing/stoping to turn or something to that effect
 

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It doesn't have a choke so no way you can check it.

As your mechanic friend said you may have a sensor problem that is causing the ECM to supply to rich a mixture when the bike is at idle. If you can get access to a service manual there a whole page of possible things that could be causing your issue. It is page 9-5 in my manual.
 

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If it is running like a dream book in at a local garage/testing station that has exhaust gas analysis equipment, tell them you want a ride in test. Then get yourself along at the agreed time and they can insert a probe in your exhaust :roll: and give you definitive info.
 

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Try cleaning the Gas Cap thoroughly.
They can get clogged and won't vent and then cause vapor lock and stall out your scoot.
This happened to me twice before I started cleaning mine twice a year and no more stalling.
It also happened to a friend that has an older 400 as well and he too cleans his gas cap regularly now.
I soak mine in degreaser and then thoroughly rinse and dry completely.
It is a quick and easy thing to do and if it works it will be a cheap fix.
As far as the rain goes it might just be the humidity making the air thicker and not venting worse.
Good Luck!
 

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Discussion Starter #7
I will clean the fuel cap...

but i still question how come it will re-start with no problem in a dry environment and in a wet environment it won't... that makes me think i have an electrical issue..

that is what concerns me..

last night i took apart everything.. i figured since i'm at 30,000 miles, i should do a valve adjustment.. it can't hurt and it is one of the trouble shooting recommended fixes... but its mechanical and not electrical... while looking at some of the parts, i noticed the IAP sensor from the air cleaner box was a bit "oily".. so i took it and cleaned it gently.. i am going to attempt to ohm it out tonight or tomorrow to see if it falls within spec's... i would suspect i'll do the same for the IAC valve.. One issue i have.. i cannot find these parts on the internet.. i fear i will have to go straight to the dealership for them... and that's going to leave a mark...

anyway... if anyone has suggestions on the whole "wet" issue.. sure could use the help

thanks
 

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I had a similar problem with my K05, I turned the idle up to 1200 RPM and it has not stalled science.
 

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The service manual spec for idle speed is 1400 ±100 rpm. My '03 idled at 1300 when I got and had a tendency to stumble a bit at idle--I raised it to 1450 rpm and have had no problems. Note that I used an external tachometer when setting the idle as the dash tach is not that accurate, it reads about 1600 rpm with the idle set to 1450 per the external meter.

OP, try raising the idle speed just a bit as suggested by "12string" it may indeed correct the problem.

You may also wish to check the throttle position sensor setting:



The "special tool" is just a SPST toggle switch that is connected to a pigtail beneath the windscreen cowling--a small piece of wire bent into a U will work just as well...

 

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I have to admit right off that I don't know much about scooters. However, when I used to have that same problem with an old car I owned it turned out to be the distributor cap, which had a bad seal and allowed moisture to get in not only on wet days but when humidity was high in the early morning. Like I said though, I don't know that much about scooters. Do they even have distributors?
 

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Not much distribution required on a single cylinder engine.

The purpose of the distributor is to "distribute" the HT output from the coil to the appropriate plug, at the appropriate time. This was when there was a single coil to generate the HT, and it gave a constant output, so a single input would be sent to multiple outputs via cam controlled contact breakers (points), and the timing was done by adjusting the distributor position..........ahh the good old days!

Nowadays, the spark is electronically controlled, commonly with each plug essentially having it's own coil-pack, and the control being on the LT side. Or sometimes there's a coil for every two cylinders (GM favors this).

Anyway, on our engines, the secondary of the coil (HT) is connected directly to the plug, and timing controlled via the ECM by the Crank position Sensor. So if you suspect ingress of moisture, the first place to check would be on the plug boot, IMHO.
 

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Does your workshop have access to test equipment that can read out the sensor values real-time?

The HealTech OBD tool would be able to do that.
 

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Fatjock said:
Anyway, on our engines, the secondary of the coil (HT) is connected directly to the plug, and timing controlled via the ECM by the Crank position Sensor. So if you suspect ingress of moisture, the first place to check would be on the plug boot, IMHO.
True on the 650 but not exactly true on the early 400 like the OP has. On it the 400 timing is controlled by the ECM and crank position sensor but the coil is not mounted directly to the plug like on the 650. It has a separate coil and old fashion plug wire and boot (or cap as Suzuki calls it).

The high tension wire is molded directly to the coil so not much chance of moisture getting in on that end unless the insulation is cracked. On the plug end there are two seals. One part number 33542-38B00 is between the plug wire and boot and the other part number 33541-44D00 is on the sparkplug end of the boot. A leak in either of those could allow moisture in.

The post 07 400 models have a similar setup except the cap end of the wire is a 4 piece assembly instead of a three part one. In addition to the cap and 2 seals it has something that Suzuki calls a cover that fits between the cab and the sparkplug end seal.
 

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Don't know if the Bugman is the same I have not looked but stalling problems
on sone Suzys were caused when wet by a drain hole getting blocked, look on
the sides of the cylinder head for a small hole going towards the spark plug
hole this is a drain for any water getting into the spark plug well passed the plug
cap seals.
 

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I know the 650 has one of those drain holes, it exits through the side of the cylinder block just behind the oil fill plug. I've never looked at the 400 to see if it has a similar drain but it would not surprise me to find out it does.
 

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Discussion Starter #16
Thanks Guys... i'm going to need some time to digest all these issues..

i will be getting back to you with the results... that's assuming i can remember how to put everything back together..
 

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Discussion Starter #17
so i may have found the culprit... i will be checking this tonight.. at least, that's my plan..

i found the lead wire that goes down into the generator (i'd post a pic if i could), i believe its the crank position sensor, is full of oil, grease and such.. i also noticed there is no protective grommet that plugs the hole around the wire.. this leads me to believe that water and other contaminants are getting inside the generator area... i believe this could be my "electrical" issue..

if water gets inside the generator area, i'm guessing that would seriously limit that spark available to restart..

so.. i am going to continue to ohm out and trace lead wires, but i think i may have found the issue.. god i hope so.. i really want to get this bike together and start riding again... gas here in WI is $3.95 a gallon and its killing me to drive the suburban...

wish me luch !!
 

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Buffalo said:
Fatjock said:
Anyway, on our engines, the secondary of the coil (HT) is connected directly to the plug, and timing controlled via the ECM by the Crank position Sensor. So if you suspect ingress of moisture, the first place to check would be on the plug boot, IMHO.
True on the 650 but not exactly true on the early 400 like the OP has. On it the 400 timing is controlled by the ECM and crank position sensor but the coil is not mounted directly to the plug like on the 650. It has a separate coil and old fashion plug wire and boot (or cap as Suzuki calls it)..............clipped..........

Which is exacly why I used term connected, and not mounted.
Had the HT lead gone from the coil to say, a distributor, then lead(s) from the distributor going on the plug(s), then the connection would be indirect. Since there are no interconnections between the coil and the plug, it is considered direct.
A trifle pedantic, I know, but when I'm being called out on it, and I'm in the right, I can't stay silent.

Having said that, the important thing at the end of the day is that the OP is getting helped.


Oakcreek eric,
While I can't rule out the CPS as the culprit, I can say that I have had my generator cover off, seen what's inside, and I don't think water getting in through the cover is the culprit.

PLease be aware that removing the generator cover provides direct access to what could be considered the sump, and the oil is omnipresent inside the area, so if you were seeing enough water ingestion to this area to affect the generator output, it would be evidenced by your oil condition.

Having said that, mine has a rubber (for want of a better term) grommet, which seals the sensor wiring as it passes through the cover.

Below are a couple of images that may help illustrate what I'm saaying.
Engine with the generator cover removed:

Though this doesn't show it too clearly, the cutouts below the oil pump drive sprocket, and indeed all along the the bottom edge of open area, go directly to the cranckcase, and the oil bath.

And inside the cover:

This should let you see the "grommet" seal I was discussing. As you can see here, if you don't have anyhting plugging the hole around the wire, you could have oil leaking out of there.

As I've said, however, this doesn't necessarily mean that the crank position sensor can be eliminated, but I'd look carefully at the wiring for damage. If none seen, it makes it less likely to be the culprit.

.......and Good Luck!!
 

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Discussion Starter #19
Figured I'd post this, as I wanted to share any information with people who tried to help or was following this thread. I appreciate all the help and suggestions.

Well... it appears my trouble was a bad coil... yep.. a bad coil that only gave me problems once it got warm and started stalling. Since the gas was getting through the combustion chamber with a low, or no, spark, it would detonate post throttle, giving me the backfires.

This has been a long going issue and i have had two dealerships investigate my stalling problem and no one ever checked for weak or poor spark. I finally did (at the suggestion of an ASE certified master auto technician) and found my coil was not operating properly.

My friend mention these types of issues are extremely difficult to diagnose because it's not until the coil gets warm/hot before it is weakened by the heat and failure starts.

So, if you start having major stalling issues, followed by backfire issues, please investigate your coil.. it may save you LOTS of time with diagnostics.
 
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