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A long-winded question for the cognoscenti.

mooseonbass

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My 2012 has a little over 20K in and has always run like a top. It usually gets in excess of 70 mpg. Lately, it has been difficult to start, I crank it for a while and eventually it back fires and starts. It seems to run fine but is getting poor mileage. The other day I was doing about 80 on the highway on a windy day and the trip odometer said about 140 miles, I can almost always get another 80 before the last red bar starts flashing. This time, the red bar came on and 5 miles later, I ran out of gas. I limped across 4 lanes of traffic and waited an hour for AAA to bring me some gas. I went another 25 miles and burned almost 1/2 of the 2 gallons they put in. Yesterday, I topped it up with fresh premium gas, added an oz or 2 of Sea Foam and went for a 75 mile ride. It was difficult to start and stalled at a stop sign, which it never does and was hard to start after that. The gas gauge hadn't moved when I got home, so that's good but this morning it wouldn't start. The last time I got poor mileage, there was a mouse nest full of poop and sunflower seed shells in the air box. Suspecting the same thing, I took the filter out (my first time doing it) and the filter was absolutely clean. I put everything back together and contemplated looking at the plugs but read that they should go a lot more than 20K and shouldn't be messed with anyway. So I pushed the starter and it fired right up, no cranking, no backfire, just the old dependable Honda start. Tried it again an hour later, same thing, perfect. My question is, could the wires to the air box sensor have been loose and my putting them back on fixed the problem? Or do you think it will begin misbehaving again. We're having rain all week but I'll try taking it to work on Friday, being sure to have a full tank of fuel, just in case.
 
You have certainly disturbed something and Imho your suggestion of the airbox sensor may well be correct. It may happen again but if it does then You know where to start looking. Hopefully it was just a slightly corroded or loose connection.
 
Given that messing with the airbox and air intake cleaner causes the issue to be intermittently resolved, sounds like the intake air temperature (IAT) sensor is either damaged, or the connector is damaged or loose.

This is the sensor that sits in the airbox, with a connector through the front cover. See [1] in the diagram. If that sensor fails, the engine will default to a pre-programmed temperature of 35° C / 95° F, causing the engine to run too rich and resulting in your range of symptoms (especially poor fuel economy).

Another likely possibility would be the MAP sensor.

Screen Shot 2022-09-19 at 07.06.17.png
 
Thank you both. If it happens again, I'll take more care to clean up the connector. Now that I know how easy it is, I won't worry about taking it apart.
 
A full load of 87 octane no-alcohol fuel woud be more beneficial than the premium fuel.
Yes, correct. Although to be clear, the EtOH vs. non-EtOH fuel is unlikely to yield any measurable real-world performance difference. But Ethanol can attract water, degrade seals and gaskets in older vehicles, and may be less stable over time in storage.
 
I don't keep gas in my tank long enough to attract water and a little seafoam works wonders for that. I had the problem before the AAA gas so I can't blame it on that. It's still raining here but I pulled off the cover and tried to start it. It fired right up! I'm thinking the sensor wire to the air box must have picked up some moisture and developed a need for a good jiggle. At least I can keep riding until it goes in for winter storage.
 
Sorry for bumping the thread, but did you get a check engine light? Will the bike throw a code if the sensor truly was loose?
 
Yes, correct. Although to be clear, the EtOH vs. non-EtOH fuel is unlikely to yield any measurable real-world performance difference. But Ethanol can attract water, degrade seals and gaskets in older vehicles, and may be less stable over time in storage.
correct indeed, but I was thinking more about the premium fuel having no benefit whatsoever in a motor tuned for 87 octane fuel.
 
My 2012 has a little over 20K in and has always run like a top. It usually gets in excess of 70 mpg. Lately, it has been difficult to start, I crank it for a while and eventually it back fires and starts. It seems to run fine but is getting poor mileage. The other day I was doing about 80 on the highway on a windy day and the trip odometer said about 140 miles, I can almost always get another 80 before the last red bar starts flashing. This time, the red bar came on and 5 miles later, I ran out of gas. I limped across 4 lanes of traffic and waited an hour for AAA to bring me some gas. I went another 25 miles and burned almost 1/2 of the 2 gallons they put in. Yesterday, I topped it up with fresh premium gas, added an oz or 2 of Sea Foam and went for a 75 mile ride. It was difficult to start and stalled at a stop sign, which it never does and was hard to start after that. The gas gauge hadn't moved when I got home, so that's good but this morning it wouldn't start. The last time I got poor mileage, there was a mouse nest full of poop and sunflower seed shells in the air box. Suspecting the same thing, I took the filter out (my first time doing it) and the filter was absolutely clean. I put everything back together and contemplated looking at the plugs but read that they should go a lot more than 20K and shouldn't be messed with anyway. So I pushed the starter and it fired right up, no cranking, no backfire, just the old dependable Honda start. Tried it again an hour later, same thing, perfect. My question is, could the wires to the air box sensor have been loose and my putting them back on fixed the problem? Or do you think it will begin misbehaving again. We're having rain all week but I'll try taking it to work on Friday, being sure to have a full tank of fuel, just in case.
Valve adjustment?
 
My 2012 has a little over 20K in and has always run like a top. It usually gets in excess of 70 mpg. Lately, it has been difficult to start, I crank it for a while and eventually it back fires and starts. It seems to run fine but is getting poor mileage. The other day I was doing about 80 on the highway on a windy day and the trip odometer said about 140 miles, I can almost always get another 80 before the last red bar starts flashing. This time, the red bar came on and 5 miles later, I ran out of gas. I limped across 4 lanes of traffic and waited an hour for AAA to bring me some gas. I went another 25 miles and burned almost 1/2 of the 2 gallons they put in. Yesterday, I topped it up with fresh premium gas, added an oz or 2 of Sea Foam and went for a 75 mile ride. It was difficult to start and stalled at a stop sign, which it never does and was hard to start after that. The gas gauge hadn't moved when I got home, so that's good but this morning it wouldn't start. The last time I got poor mileage, there was a mouse nest full of poop and sunflower seed shells in the air box. Suspecting the same thing, I took the filter out (my first time doing it) and the filter was absolutely clean. I put everything back together and contemplated looking at the plugs but read that they should go a lot more than 20K and shouldn't be messed with anyway. So I pushed the starter and it fired right up, no cranking, no backfire, just the old dependable Honda start. Tried it again an hour later, same thing, perfect. My question is, could the wires to the air box sensor have been loose and my putting them back on fixed the problem? Or do you think it will begin misbehaving again. We're having rain all week but I'll try taking it to work on Friday, being sure to have a full tank of fuel, just in case.
Had the same problem (not starting) with my 2018 NC shop had it almost 7 months and still could not get it running, got it home and started chasing wires, found that the cover for the AUX PWR connector was pointing up, dont know if moisture got in it some how. The bike sat for all that time, so it might have dried out, but it did get it started and had no problems with it after that, so check your wires
 
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