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Old 05-15-2014, 10:48 AM   #1
longhaul747 OP
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Zuma 125 difficult starting?

I seem to have an odd problem with my 2013 Zuma 125 all of a sudden. It started about a month ago I took it out for a ride and it did not fire like it should on the first start. The starter motor turns over but it just does not ignite and start. I tried 3 times and on the 4th I pinned the throttle and it started it right up.

Seemed fine for about a month and then all of a sudden it did it again yesterday. Once started it idles and runs perfectly normal. Seems to restart no problem as long as the engine is still plenty hot.

I thought maybe it was because it has been sitting because of poor weather so I took it out this morning. I thought it would fire first time but it did it again this morning. In order to get it to fire I had to pin the throttle again. Then it got worse. Even though it ran fine I was at my folks house for 30 minutes and went to leave. This time it would not start no matter what I did. This time I reset the ECU and it fired first crank after resetting the ECU.

I stopped for gas and filled it up. It was about a quarter tank before of stabilized gas put in back in February. Not fresh gas but not exactly old either. It started first hit on the starter no problem but then the motor was still plenty hot.

My next stop was at the dealer service department since I have about 2 weeks left on my warranty. They documented it and set up an appointment for next Tuesday if I need it. They said to ride it around for a few days and if it does it again bring it in on Tuesday and they will sort it under warranty. I told them about how earlier in the day it did not want to start at all without resetting the ECU. So we let it sit for 30 minutes and went to start it but of coarse it started on first hit of the starter.

The service writer said it may be likely that the ECU reset actually corrected the problem and try it for a few days and see what happens. He also mentioned that it sounds like the fuel pump issue the 09's had but stated he had to replace a few of them on later years as well. Also had to do an ECU replacement on one but that one was totally dead. He thought it was one of those 2 things.

Basically its behaving a lot like a carbed scooter with auto choke issues but these are fuel injected. Really they should start on first hit of the starter button every time.

Now its sitting in the garage for the night and I will see what happens tomorrow. Hopefully it starts without issue and the ECU reset fixed it.

I actually posted this yesterday by mistake in the wrong forum. I am about to head out on my SH150i for fuel and then when I get back I will try the Zuma again.
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Old 05-15-2014, 01:42 PM   #2
longhaul747 OP
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Interesting.....

Took it out and it fired the second I hit the start button. Road it for 10 miles and let it sit for 30 minutes. Fired up again no problem.

So its one of several things. Either the gas in it before was flaky or perhaps some pressure was built up in the gas tank and opening the gas cap fixed it. Usually the pressure built up in the tank prevents them from running well period but who knows.

I think the most likely candidate is the ECU. The Zuma 125 is notorious for a slow setting ECU and dramatic temperature changes can prevent the mixture from being proper for start up. Seems to have happened to several over at the Zuma forums. Sometimes the ECU reset works though and sometimes it does not.

Will ride it around for the next week and see how it bahaves. Might comeback once the tank is below a half tank but will just have to see. This is what has me concerned is I had a problem a month ago and it went away but came back again yesterday. First time it almost left me stranded if I did not know the ECU reset procedure. Thank god for smart phones and I was able to search Google for "Zuma 125 ECU reset".
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Old 05-15-2014, 07:08 PM   #3
JerryH
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Depending on how long it sat, I would suspect ethanol damage to the fuel system. I let my XT225 set for about 6 weeks, then tried to start it. It was very hard to start, finally started, but misfired and would not idle. I took the carb off and removed the float bowl. I found a significant amount of corrosion in it. Gasoline does not cause corrosion, so it had to be ethanol. It can also damage the fuel tank, fuel pump, and injectors on an EFI system as well.

The book says to reset the ECU after having the battery disconnected, but I never have, and it still ran fine. I make sure I start it up and let it run for several minutes once a week even if I don't ride it. I also rock it back and forth to remix any gas/ethanol in the tank that may have separated.
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Old 05-15-2014, 07:48 PM   #4
longhaul747 OP
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Quote:
Originally Posted by JerryH View Post
Depending on how long it sat, I would suspect ethanol damage to the fuel system. I let my XT225 set for about 6 weeks, then tried to start it. It was very hard to start, finally started, but misfired and would not idle. I took the carb off and removed the float bowl. I found a significant amount of corrosion in it. Gasoline does not cause corrosion, so it had to be ethanol. It can also damage the fuel tank, fuel pump, and injectors on an EFI system as well.

The book says to reset the ECU after having the battery disconnected, but I never have, and it still ran fine. I make sure I start it up and let it run for several minutes once a week even if I don't ride it. I also rock it back and forth to remix any gas/ethanol in the tank that may have separated.
That was my thinking as well. Some issue with the ethanol fuel even though I use a mix of K100MG and a bit of TCW3 2-Stroke oil in the mix to prevent ethanol issues. Been doing it in other bikes for 3 or 4 years now without issues and some of them have sat for a long time. My DL1000 sat since August 31st and it ran fine this Spring and I just filled it up last week. Could not tell the difference and I did not loose anything against my average MPG. My SV's were topped off September 7th last year and I am just now getting to the opportunity to burn it off. They run fine!

The Zuma 125 was filled up in late Feb this year. In late March it went in for its 600 mile service and then was parked briefly because of weather after that. Then in mid April it was taken out and that is when I had the first starting issue. It then improved after that for a half dozen rides and then it sat again until 2 days ago when the drama started again.

Just not a lot of time for the fuel to go bad especially with my home brew I use. However a 1st time for everything and it did sit a bit being half full witch is kind of a no no but being in doors is not so bad.

Sometimes you just get bad fuel that causes weird problems and it goes away when you fill up again. Not often but it does happen.

I am still not ruling out fuel but my non mechanical knowledge is telling its the slow ECU. Last time it was ridden it consistently it was much colder. When I took it out April was the 1st really warm day of the year. Then it got colder and ran fine again. Then 2 days ago it was hot outside again and it happened again. This time even worse because it was much warmer. Resetting the ECU forced it to readjust for the warmer air.

Now I am not sure its a defect or not? Over at the Zuma forums it has been discussed that the ECU is slow to learn and sometimes has to be reset. However its not a frequently reported issue. Most of the starting issues were related to the fuel pump on the 09's during warm weather.

My guess is if the bike was actually being ridden every day the slow ECU would be given an opportunity to slowly adjust to atmospheric conditions slowly as they change. However if was ridden when its 35F and then put away and pulled out of storage when its 90F then the ECU will have the incorrect fuel mixture for the start and it would not start properly.

Its my opinion that even a basic fuel injection computer should be able to adjust for temperature on the fly but maybe not. Another theory for the few bikes that have this problem is a poor temperature sensor. It works enough to not through a code but gives incorrect readings to the ECU. Nobody that I know of has replaced this part though.
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Old 05-16-2014, 03:36 AM   #5
JerryH
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If it didn't sit any longer than that it is probably not ethanol, though it could still be bad gas. Most places say an ECU will take up to 50 miles to "relearn" everything, but mine started right up and ran fine after having the battery out for a few days, and I didn't reset it.

After about a month of not being disturbed, a tank (or carb float bowl) full of ethanol gas will start to separate, and the heavier ethanol goes to the bottom. It is extremely corrosive, and can rust the bottom of the tank, and corroded the carb float bowl. If it sat for as much as a month, the gas in the tank could have started to separate, and the pump could have picked up some that had too much ethanol in it. If that were the case, running a tank full of fresh gas through it should clear it up. Unlike a carb, there is no place for gas to sit in an FI system, other than in the tank.
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Old 05-16-2014, 03:24 PM   #6
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Some people claim to have had as many problems as I have, some claim they have never had any problems. There doesn't seem to be anything in between. I have had 2 Honda dirt bike petcocks fail, and leak badly. Honda petcocks are put together with rivets, not screws. I drilled out the rivets, and found the rubber parts inside melted. Later, on the same 2 bikes, both oem Honda plastic gas tanks literally fell apart. Cracks everywhere. Vents were open. End of vent hose (on the gas caps) turned to mush more than once. Had to rebuild the petcock on my Vulcan 750 3 times, because the rubber seals inside melted. Had to rebuild the carbs once, plastic float cracked, rubber O-rings melted, float bowls and jets corroded. One of the coasting enrichener diaphragms melted, a $65 part. Tank vent hose on my XT turned to mush on the open end several times. Rebuilt petcock once. Have found corrosion in the float bowl twice.

And the worst thing I ever saw was my ex father in law's Honda generator. He let it sit over a year with gas in it. We got it running by spraying gas out of a spray bottle directly into the carb, but it would only run as long as you kept spraying gas. I took the carb apart, and wish I had taken a picture of the float bowl, which was made out of steel. It was rusted solid. It looked like someone left a rusty SOS pad in it. Finally got the jets out, but both the jets and float bowl were too far gone to save and had to be replaced. I've gotten to where I drain the gas out of carbs if the engine is not going to be started for more than a week. Counting those 2 gas tanks and petcocks (which I did not replace) I've had around $1500 worth of damage done to motorcycles by ethanol, not counting all the labor to take things apart and clean them. The tanks were like $450 apiece new.

Now the strange part. I have 2 old cars, a '64 and a '72. They sit with gas in them all the time, including the carbs. Yet I have found no signs of ethanol damage. Ethanol just doesn't seem to like motorcycles, at least around here.


Here are a couple of pictures of carb damage caused by ethanol.





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Old 05-16-2014, 04:42 PM   #7
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FWIW, Yamaha sent out a service memo to dealers about six years ago stating that all Yamaha motorcycles produced since 1988 have ethanol resistant fuel systems. It might be a bad tank of gas, a bit of water, trash that got into the fuel injector. I've notices that small engines are much more susceptible to fuel problems than large engines, because the jets, passages, and injectors are so much smaller and it takes a whole lot less to clog them.
The photos from Jerry's issue of the day with modern life are pretty much what you'd see if you opened up any carburetor that's been sitting a very long time. If you go to the junkyard and open up a 20 year old carburetor that's been sitting full of gas since before ethanol was introduced, it's going to look pretty much like that.
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Old 05-16-2014, 07:23 PM   #8
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Don't think it is an Ethanol or bad gas issue. Pure guess is a possible fuel pump or fuel pump relay at fault? The Zuma had issues in '09 with faulty fuel pumps, corrected by Yamaha.
Zumaforums might be your friend.
You should be able to hear the pump come on when the key is turned.
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Old 05-16-2014, 07:33 PM   #9
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From your original thread, in case you haven't seen the reply.
Quote:
Originally Posted by k-moe View Post
That does sound exactly like the fuel pump problem the '09s had. I finally ordered an aftermarket fuel pump to correct the problem on mine (the Yamaha replacement pump also had the same issue). The problem with the '09 pumps was caused by insufficent clearance between the impeller and the impeller housing, which causes the pump to bind when it gets hot. It is possible that the same problem is cropping up again since it was a manufacturing error, and Yamaha (to my knowledge) is using the same vendor to source the pump.
I never had any starting issues after replacing the Yamaha pump with an aftermarket pump. You very well could have another problem (such as a poor connection to the head temp sensor), so don't jump to conclusions until you've ruled out other possibilities.
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Old 05-17-2014, 12:39 AM   #10
longhaul747 OP
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Road it around today and into work. Not a hint of trouble so far but I am cautiously nervous. Every time when this happened the fuel pump always primed or at least made the sound. So that is a good sign I guess. I also know to wait for the pump to prime before starting so it was never that issue.

Its either bad fuel and filling it fixed it or a hung ECU and resetting fixed that issue. I now kind of wish I did not reset the ECU until after the fill up but I was dead in the water until I tried something.

Next time I have a bit of spare time (hopefully this weekend) I can inspect the connection to the thermal sensor. I don't think it would even be that difficult to replace the thermal sensor if necessary. Looks like a $20 part!

I also have not ruled out a fuel pump issue. Dealer service writer said Yamaha has issues with fuel pumps on many bikes and especially the Zuma 125. Not just the 2009's either. He has seen a few go bad on later years.
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Old 05-17-2014, 09:06 AM   #11
k-moe
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If it ends up that you want to put in a different fuel pump, PM me and I'll get you in contact with someone who can get you one.
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Old 05-17-2014, 08:45 PM   #12
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I had Yamaha replace my fuel pump after it would not start.
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Old 05-18-2014, 11:50 AM   #13
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If the fuel pump comes on and pressurizes the system when you turn the switch on, it is likely ok. You probably won't have any more problems with it. Mine has set for several weeks at the time, but I always started it up at least once a week and let it run at least 10 minutes, to run fuel through the system. I do that with all my bikes except the XT, which has been put away for the summer, with an empty washed out plastic tank, and a clean carb full of WD-40.

Those carbs are from a '79 Goldwing. The other 3 looked the same. The owner had cleaned all four carbs and done some other maintenance on the bike. He rode it for a few weeks, then due to a situation change, the bike got parked in the garage where it sat for about a year. He then tried to get it going again, without success, and finally pulled the carbs. That is what he found. Any carb is going to be all gummed up if you leave gas in them for a year, but that is not gum and varnish. It is corrosion. And pure gasoline does not cause corrosion. The gas and ethanol separated, the gas evaporated, and the ethanol did most of the damage.

I hope the fuel pump on my Zuma 125 doesn't fail. It would be just my luck for it to happen 100 miles from home. I wonder why Yamaha is still buying defective fuel pumps?
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Old 05-18-2014, 02:49 PM   #14
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Took around for some errands this afternoon. My Zuma did not miss a beat. I almost want to say the case is closed and the ECU reset corrected the problem but I have a feeling it will happen again at some point. With a week left on warranty unless I opt for the extended warranty I am kind of hosed unless it just magically goes back to not wanting to start in the next week and I can get it into the shop.

One thing mentioned is I was going to inspect the thermal switch and connection this weekend but flat ran out of time. Its probably okay anyway as the ECU would need to communicate with this part for proper start mixture and temperature.
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Old 05-21-2014, 06:52 PM   #15
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This is interesting. I had an appointment setup for yesterday just in case the problem was still there. I stopped by yesterday and told them that so far its not doing it and I tried every scenario I can think of and it did not miss a beat.

Today I get a call from the service writer at my dealership I do a lot of business with. They have a Majesty in the service bay (very new) with the exact same problem. So they called Yamaha today for that scoot and they mentioned mine as well. In both cases it turns out to be a bad fuel pump. Yamaha is almost 100% it is and apparently they have a TSB on some recent model year Yamaha products with fuel pump problems.

So without ever needing to stop in and have the dealer officially diagnose the problem they were authorized to order a new fuel pump and replace it under warranty. So my Zuma is going in for a new fuel pump when they get it in next week sometime.

Apparently its very likely the problem will come back when it gets very hot outside and humid. I still think its odd that the ECU reset fixed it on that very same hot and humid day but that is what Yamaha is saying. What I want to do is get the fuel pump replaced and have it documented and then if it ends up being something else perhaps I can get the real problem fixed under warranty if it is indeed something else. It does sound like the classic Yamaha fuel pump issue haunting many other Yamaha products though.
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