Low fuel no start

I learned something new about my new FJR yesterday. I was 35 miles into the "count up low fuel mileage counter" when I arrived at work. There was no time to stop for gas before work so I planned on stopping after work. I parked sideways on a slight downhill with the kickstand toward the downhill side. When I tried to start the bike, it sputtered and died. Another attempt yielded the same result.

I knew I was about 50 miles overdue for my 600 mile service :blink: , but I'm pretty sure the bike wasn't already broken because of that. Luckily I had already had the tank off to adjust throttle freeplay and I seem to remember that the pump pickup was on the right side of the tank (the side that higher up when the bike is on the sidestand). So I finished putting my gloves on, sat of the bike and tipped it upright. A quick stab on the starter and it fired right up.

A couple miles down the road I filled up with 6.1 gallons of gas. That tells me that there was still a half gallon left in the tank. I guess that's not enough if you're leaned over. I wonder if the bike would die if you were hard over in a long left turn?

Yes it could die or sputter....but it would have to be a very long duration turn. It's more likely to die one goes up a long grade as the fuel rests in the back of the tank. Had the latter happen grinding up the 6% or so of I-80 towards Park City last month and found myself purposely tossing it back and forth for it to get to the low-spot on the right side.

If one is in the reserve...it might be prudent to park the bike on the centerstand until they make it to the gas station.

When the fuel tank is getting low; if I start the bike on the side stand the low fuel meter comes on. Once ridden a couple of miles it goes back to 1 or 2 bars. So if you are that low, yes you need to park on the center stand or center the bike before starting. I have a very bad habit of ridding/driving my vehicles on the low fuel light. Unfortunately I have also had to replace a couple of fuel pumps in my cars because of it. This is my first bike with at fuel pump, others were gravity fed; hopefully it does not suffer a similar fate!

A very bad design indeed. Just setting the bike on the sidestand on flat ground gets 3 bars off the fuel level gauge. Most bikes have the 'hole' on one side of the tank for packaging reasons, but a few pennies more gets extra tubing inside to locate the pump assembly in the middle and rear (lowest point) of the tank, like BMWs.

And yes, with a returnless system, I bet a sweeping left turn would have you at least sputtering if fuel is below pump's pick up level, but don't plan to find out. The better question is at which gas level would that happen. Based on the 3 bar drop on my bike, it can be as much as a 1/4 tank. Not good.

JC

ELP_JC said:

A very bad design indeed.

Click to expand...

WTF? A bad design? I have to disagree. I don't see how keeping the bike level to avoid any problems is a big stretch on rider's part. No big f'ing deal. The design works just fine.

My comments in blue:

ELP_JC said:

Just setting the bike on the sidestand on flat ground gets 3 bars off the fuel level gauge. (So what. Don't turn on the ignition until the bike is level. That's not that hard to do)
Most bikes have the 'hole' on one side of the tank for packaging reasons, but a few pennies more gets extra tubing inside to locate the pump assembly in the middle and rear (lowest point) of the tank, like BMWs. (Have you ever had the tank off? There is no low point in the middle rear. The whole rear half of the tank is the low point. And it works just fine.)

And yes, with a returnless system, I bet a sweeping left turn would have you at least sputtering if fuel is below pump's pick up level, but don't plan to find out. (NOT. Unlike a car, a motorcycle leans with the turn and so the resultant of all forces are still acting through the vertical axis and Cg of the bike. IOW, the fuel is not being sloshed to one side or another during a turn. You would need to be concerned with going up or down hills, but only if the tank is nearly empty, not as you say below.)

The better question is at which gas level would that happen. Based on the 3 bar drop on my bike, it can be as much as a 1/4 tank. Not good. (Where do you get this stuff? I consistently take my tank 30-40 miles into reserve and have never experienced any problems. 1/4 tank my ass.)

JC

Click to expand...

Not going to argue with somebody who apparently didn't make it past grade level. If you lean your bike the same angle either on the sidestand or while riding, fuel will be at exactly the same position; simple physics. And no, I don't give a rat's a$$ if fuel gauge is 3 bars below while inclined, but it's a fact, and I was just pointing it out. And yes, it's a bad design indeed; if you can't see it, you're blind or worse. Pump should be in the middle of the tank to avoid that effect, like on most other bikes. Not critical, so a nice place to cut corners, just like eliminating the baro sensor. You've been attacking my posts in an unwarranted way (WTF, etc), rather than disagreeing in a civilized way, and you don't seem to go away, and can't put you in my ignore list (which I'd have done a long time ago), so it's time to stop bending over so you can have your fun. Later.

JC

What the fuel gauge does when the bike is tilted over on the sidestand should be of no consequence. As long as it's fairly accurate when the bike is upright that's all that matters. The fuel sender float is aligned from front-to-back in the tank. The pivot point of the float assembly is almost directly below the fuel tank cap. The float assembly projects back from that point and pivots up-and-down. The float is located about 2" to the rear of the rear edge of the fuel cap assembly. So obviously it's going to provide an erroneous indication when the tank is tilted to the left or right for an extended period of time. The computer likely sends a moving average of the fuel sender data stream to the fuel gauge display. So an erroneous indication will soon self-correct once the bike is upright for awhile.

The fuel pickup for the pump is at the bottom of the tank almost directly under the fuel tank cap. The pickup is below the lowest position of the fuel sender float as one might expect.

To be bitching about an erroneous fuel indication when the bike is on the sidestand is just a bit absurd. It should quickly self-correct once you begin moving down the road.

ELP_JC said:

If you lean your bike the same angle either on the sidestand or while riding, fuel will be at exactly the same position; simple physics.

Click to expand...

Sorry, but this isn't correct. Any single-track vehicle like a motorcycle which corners by leaning has all forces acting through the axis of the bike so the fuel stays level in the tank throughout the turn. Tape a spirit level across your bike sometime and go riding - while cornering, it will show level no matter what the lean angle.

- Mark