Gas tank overheating?!

[Sparta82]

Hey all,

I have a problem with my NC700S that doesn't seem to be reported anywhere. I'm stuck for now as all garages are closed on Monday's in Nanaimo BC. After 22 000 km this summer, of course this happens when I'm finally just about to my destination (less than 500km away)!

My seat started getting hot at some random point in time, nothing particularly different about conditions or my driving, and would cool back down on deceleration, and warm back up on acceleration. I went about 30 km like this to get into town and the seat got pretty hot. So if the seat got hot enough for me to feel it, that means whatever it was overheating meant business.

Upon inspection, that is removing the seat and trying to feel what was heating, we can hear a buzzing sound that trips up when applying gas in neutral. I haven't been back on the road yet to see if the heating still was happening, but the sound seems to be coming from the back left side of the tank. Also, for the last 2 days, I've had some trouble starting it in the morning, would need to give some gas a bit before it would get going, but would start perfectly during the day when stopping for gas/food.

I'll be bringing it to a mechanic tomorrow, but if any of you have had similar issues or have thoughts, please let me know.

Thanks.
Sparta

 

[caldercay]

My seat started getting hot at some random point in time, nothing particularly different about conditions or my driving, and would cool back down on deceleration, and warm back up on acceleration. I went about 30 km like this to get into town and the seat got pretty hot. So if the seat got hot enough for me to feel it, that means whatever it was overheating meant business.

Upon inspection, that is removing the seat and trying to feel what was heating, we can hear a buzzing sound that trips up when applying gas in neutral. I haven't been back on the road yet to see if the heating still was happening, but the sound seems to be coming from the back left side of the tank. Also, for the last 2 days, I've had some trouble starting it in the morning, would need to give some gas a bit before it would get going, but would start perfectly during the day when stopping for gas/food.

Random thought ... fuel pump. I'll check the Service Manual to see what else is around there.

 

[Sparta82]

Thank you! I unfortunately couldn't find a service manual before I left on the trip so am going blind for now.

 

[caldercay]

Verified ... only thing under the seat is the tank and inside the tank is the fuel pump (right under your bum at bottom of tank).

The "buzzing sound" is no doubt the fuel pump - if you turn off the ignition, hit the kill switch, turn the ignition on, then listen carefully as you turn the kill switch into the run position, you'll hear the pump fire up.

When it gets hot like that, have you popped up the pillion seat and open the gas tank cap (engine off) - is there pressure build up?

 

[Sparta82]

We're heading for our campsite, so I'll check for pressure there. We definitely hear the fuel pump fire up. That would make sense and probably explains my issues with starting the bike. Thank you!

 

[houssam2]

We're heading for our campsite, so I'll check for pressure there. We definitely hear the fuel pump fire up. That would make sense and probably explains my issues with starting the bike. Thank you!

You probably shouldn't use "fire" up and "fuel" pump in the same sentence But seriously, I'm not sure you should ride it until you get it checked out.

 

[happy]

Fuel tanks and fuels do not just get heated up.
If they did, an explosion is likely.

I am also guessing it is some sort of fuel pump and you must get it sorted out asap, because of the obvious risk of fire or explosion (gas pressure).

I hope you fix it soon. Sorry I cannot help more than just sympathise with you.

 

[L.B.S.]

Fuel tanks and fuels do not just get heated up.
If they did, an explosion is likely.

I am also guessing it is some sort of fuel pump and you must get it sorted out asap, because of the obvious risk of fire or explosion (gas pressure).

I hope you fix it soon. Sorry I cannot help more than just sympathise with you.

Fuel and fuel tanks (and carburetors etc., of course) have been getting very, very hot for ever, my friend. It is not the ideal condition as far as energy efficiency goes of course, but fuel can boil quite merrily, with no expectation of explosion. The cooler the fuel the better for power and performance, but it is warm to hot in a gazillion vehicles, and always has been.

I've owned countless bikes that the fuel tanks (naturally, not due to a particular part failure or problem) got so hot as to cause nasty burns, if you touched them. Fuel often boils in carb float bowls, causing a common term: vapour lock.

Heated fuel does expand, and pressure is increased, but unless you have a plugged or closed system, the excess vapour/pressure goes where it always has- either vented to a recovery container, or simply to atmosphere.

A faulty internal tank fuel pump that is overheating will more than likely just stop working eventually. Having it create sparks to the point of vapour ignition or fire is pretty remote really, IMHO.

 

[happy]

Fuel and fuel tanks (and carburetors etc., of course) have been getting very, very hot for ever, my friend. It is not the ideal condition as far as energy efficiency goes of course, but fuel can boil quite merrily, with no expectation of explosion. The cooler the fuel the better for power and performance, but it is warm to hot in a gazillion vehicles, and always has been.

I've owned countless bikes that the fuel tanks (naturally, not due to a particular part failure or problem) got so hot as to cause nasty burns, if you touched them. Fuel often boils in carb float bowls, causing a common term: vapour lock.

Heated fuel does expand, and pressure is increased, but unless you have a plugged or closed system, the excess vapour/pressure goes where it always has- either vented to a recovery container, or simply to atmosphere.

A faulty internal tank fuel pump that is overheating will more than likely just stop working eventually. Having it create sparks to the point of vapour ignition or fire is pretty remote really, IMHO.

That's the wonder of info sharing in a forum.
Man, I learned something today!


Thanks!