SOLVED (I hope): Bad gas? Or something else?

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mukaiboston
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SOLVED (I hope): Bad gas? Or something else?

Post by mukaiboston »

For those of you who have read my previous posts, I just had my CVT rebuilt, my valves adjusted and my air filter replaced in the spring so my scooter has basically been operating like brand new until last night.

Over the weekend, I was low on gas so I topped off the tank at the Exxon station by my house and parked my scooter. Last night, I took it out on the road and, within about 10 miles, the check engine light came on. I figured maybe it was due to the change in weather since for the past few weeks we've had astronomical humidity and heat and yesterday was cooler with no humidity.

Parked it at a coffee shop and reset the ECU just in case. Then I rode from the coffee shop to my parents house with no incident.

When it came time to go home, the check engine light came on when I turned the key, went off and then turned on again and stayed on even though I had not started the engine. At this point, I was like, I just need to get home. As I was riding, the idle became very rough at traffic lights...loud and lots of vibrating. If the motor idled more than about 10 seconds, there would be a chance that the engine would die as soon as I pulled the throttle. All I had to do then was hit the ignition and it started up and went, but it's obviously scary to have the engine die like that.

The way I was able to ride the 12 miles home was to get on the state highway. All the problems I've had are at idle only or going from idle to in-gear so I knew once I was accelerating to 50-60 mph, I was going to be safe. And then at stops, I just revved the engine every few seconds to prevent it from dying.
==

The last time I had symptoms like this was when I used BP gas. You can see my other posts on this and user HanShan has also posted twice about this. BP gas both caused our scooters to idle at high rpms and my scooter's check engine light would come on and it would die when accelerating from a stop. I fixed this issue by running down that tank and filling with Shell or Exxon. I gave BP another shot and the same thing happened. This is why I'm wondering if the gas is to blame and the fact this happened within 10 miles of filling up the tank.

BP with Invigorate = Lousy Running Blur
http://www.modernbuddy.com/forum/viewtopic.php?t=30612

Problems with BP gas?
http://www.modernbuddy.com/forum/viewtopic.php?t=30578



Is anyone familiar with my latest symptoms? I'm hoping I just got a batch of bad gas and I hope I can run the tank down and fill with something else. If not, I guess there is something clogged in the fuel system. Does the Buddy 170 have a PVC valve? It's odd that the scooter sometimes dies when I give it gas after it idles for several seconds, but then I can fire it right up and go from zero 60 mps in like seven seconds. I threw in a few drops of seafoam just in case it helps.[/b]
Last edited by mukaiboston on Mon Jul 31, 2017 1:53 pm, edited 1 time in total.
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giddyup98
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Post by giddyup98 »

My Check Engine light came on a few weeks ago, but I didn't have any of the symptoms that you're experiencing. Mine was caused by too much oil in the crankcase. As soon as I removed the excess, it was fine.

I've been told that the Check Engine light will also come on if the engine is running excessively hot. Not to say this is your problem, but it's something to consider.
2009 Genuine Buddy 125
2012 Genuine Buddy 170
2005 Vespa GT 200
mukaiboston
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Post by mukaiboston »

Are you talking about the motor oil? How much would be too much? Mine is a little over, maybe half a centimeter over, but I wouldn't imagine overflowing would cause symptoms such as this.

I've also run the scooter in very hot temps. 90F or 35C for long periods and have not have it overheat. We've just had a heatwave pull away so it is much cooler now.
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giddyup98
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Post by giddyup98 »

Mine was significantly overfilled. I think I had to remove close to 60cc of oil. I doubt that this is your problem. Overheating is probably out too then.
2009 Genuine Buddy 125
2012 Genuine Buddy 170
2005 Vespa GT 200
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DeeDee
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Post by DeeDee »

Mine came on running 3 exits on the freeway doing 65 on a 90 degree day. It went into limp mode. I pulled into the gas station filled up, waited 5 minutes, and it was fine.
mukaiboston
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Post by mukaiboston »

This sounds really dumb and I don't know for sure this was the cause of the problem, but it's possible my gas cap was not on securely.

The 170 gas cap has two latches that hook when you push down on the cap (unlike the other Buddy's which screw on). If you push the cap at an angle, it is possible that one hook will click, but the other won't. So the rubber seal won't be flush against the metal rim.

I had to start searching automobile forums of all places - because most scooter forums deal with carburators which is not helpful for me - and people were saying that the fuel system needs to be sealed or the vacuum system will not work right because fuel is sucked through the injectors and then returned to the tank.

So my guess is the engine light was on because it detected gas vapors escaping the tank or a vacuum leak and the scooter couldn't accelerate right because ambient air was getting sucked into the fuel system.

So when the engine light comes on, check the gas cap first and make sure the gas cap clicks all the way down and then pull on it just to make sure it is not loose.
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