A bike stall... and a fix
My Rebel 500 ABS has only 200 miles on it. Riding last weekend, the engine stalled at about 20-25 mph. The engine appeared to surge a bit as the bike started to lose power. I engaged the clutch and opened up the throttle but the "check engine" light came on and bike stalled and died (on 4th gear). Thankfully this was not on a busy road (or freeway) and I easily pulled off to the side of the road. I tried starting up the bike again after turning everything off. It spluttered to a start, then died, as though it wasn't getting gas. My tank was full. I was about a mile from home and dreaded the thought of having to walk the bike back.
I waited for several minutes, managed to start the bike again and rode it back, really slow, fearing that I might be doing some real damage. It spluttered several times on the way, but didn't completely cut out. A few hours later I took the bike out again, but couldn't make it around the block before it stalled again (ie, died). But no check engine light came on when riding. I managed to start the engine (turning many times before firing) and got back slowly.
At this point the option was to get the bike towed to the dealer and have him take a look.
---- readers, you can start your diagnosis here if you like, before reading ahead ----
Here was my approach.
I had fueled the bike up the previous evening. I rode back about a mile from the pump with no issues. I struggled filling the tank (still have to learn how to gas up a bike properly). It dribbled in very slowly the whole time and I had spilled a bit of gas on the floor (through the overflow pipe) since I had not stuck the nozzle all the way in.
My first thought was oil levels (since the engine light had come on). Since you need two people to check the oil level (from the see-though gage below your right foot), I did that as soon as I got home. All good. So the "check engine" light had just come on because the engine had cut (as it should).
I wondered if I had added/dissolved too much air to the gas when filling (given my poor technique) and that was causing the stall. Or if somehow the gas had picked up some water. Or just bad gas.
The next day I happened to open the gas tank and found that the gas level was very high (when on side stand) and still very high when the bike was straightened. I wondered if there could be a problem overfilling a tank. I read this up and found that (at least) two things that could happen:
(1) All bikes have an EVAP (evaporative emissions system) that captures gas fumes (into a charcoal canister) and releases the condensed gas back into the tank. The idea is to prevent vapors from venting into the atmosphere on hot days. The charcoal shouldn't be catching wet fuel, just fumes. If an tank is overfull you could soak the canister.
(2) The fuel pump on a bike pumps the gas from the tank into the cylinders. Any pump would need the air pressure in the tank to be at atmospheric pressure, or it would have to work really hard against a vacuum. An overfull tank has no air in it at all, or a way to get any in.
It felt as though my issue might be problem (2). The overfull tank was actually starving the fuel pump. I probably managed to ride a few miles after filling up, since the fuel lines had some gas in them.
Today, I bought some rubber tubing and siphoned off a bit under 2 liters (1/2 gallon). It took more than a liter before the levels started to go down visibly from the top.
Took out the bike for a ride and managed 5 miles WITH NO GLITCH WHATSOEVER. Hope this is the end of the problem and the fix was this easy.
Anyway, I decided to share this detailed post so you all know that overfilling a tank can be a real problem.
Last edited by SeventhGear; 04-04-2018 at 07:25 PM.