Without a doubt, the Fit's seminal feature is its Magic/Ultra seat config system... achieved as we all
know (at some expense?) by moving the fuel tank forward to it's now "central" position under the
front seats.

Clearly, in order to get fuel from the fuel filler to the fuel tank, something fairly circuitous is happening.
And possibly more than just gravity? Pressure? It appears that the center floor hump in the rear seat
footwell is quite a bit lower than where the top of the fuel tank is???



Do we know what route the fuel line takes, if this has anything to do with the problems people seem to have
with filling / topping-off their tanks? And is this why the rear suspension isn't independent?

The gymnastics here seem like something that would have evolved from some of Honda's fairly involved motorcycle fuel
tank arrangements, e.g., on the ST1300, with it's split fuel tank.

Thoughts?

 

Interesting question, in for answers!

 

What problems do people have topping off other than possibly damaging their fuel system? (topping off fills the area needed for expansion in a pressurized system forcing liquid fuel into the evaporative recovery system or bursting the system.)

Most cars in this class have the same type of suspension: rear torsion beam. (check Yaris and Versa). It's "semi independent," lowers costs, and doesn't take up as much interior room. If anything moving the fuel tank forward would allow more room for the suspension so you can't blame it on that.

Agree the fuel flows pretty far to get into the tank compared to any other car.

 

Trouble with fuel tank, for example:

Fuel Tank Trouble

Fuel Tank Capacity

Fuel Noise

Trouble Filling to Capacity

 

Other than hearing the gas slosh around these are issues explained by an out of adjustment pump nozzle or user error.

"I filled my tank really slow" (he defeated the auto cut-off on the gas pump nozzle)

"The pump cut off before it was full" (faulty nozzle)

This happens with all cars.

Depending on the pump sometimes I can't get it to flow at the maximum rate. The auto shut-off triggers when I just started to fill, or periodically during the fill. Never had that happen on the Fit. Yet.

Don't restart the pump if unless it's obvious you're less than full. By obvious I'd say many gallons less than what you think it should take. If you're not sure, don't try to restart it. You'll end up overfilling (not necessarily spilling fuel) but compromising the car's fuel system.

 

When it warms up tomorrow I'll stick my head under my car and see if I can figure out where it goes.

 

I just really want to say, I love that diagram. Hee!

 

Agreed.

Had the rear suspension been anything else but an H-shaped torsion beam, I doubt Honda would have made the Magic Seat system work. If they did (I'm imagining BMW's rear "Z-axle" suspension design), the Fit/Jazz wouldn't have been as cheap as it is, either.

 

Hey thanks!

Exactly. Most articles at the Fit's introduction (first or second gen), attribute the Magic-Ultra system to the fuel tank location.... but after researching this further, several intro articles on the 2004 Jazz/Fit pointed out that it was the combination of fuel tank location AND the compact, h-shaped torsion beam suspension. No one seems to discuss the fuel line gymnastics... which must have been interesting to solve.

Remember, that in many markets, the Jazz/Fit is marketed with no spare tire and a luggage system called ULTRA LUGGAGE... where our spare tire well is another part of the TALL configuration... with a set of flaps that can be rearranged to accommodate different types of storage.

 

That upper/lower mode is pretty interesting. Is the spare tire well differently-shaped? Is the cover sturdier than the North American one, then? I think the Canadian spare tire-less Fits just have the same thing as the US ones...but no spare tire in the well.

I'd almost consider leaving my spare home for that extra storage, but they I do I'll have a blowout and be pissed at myself for leaving it!

As for fuel troubles, it seems all those links are from people abusing their tanks...that can happen on any car and is not unique to the fuel path.

Though I am also interested in just how the filler runs.

 

Pretty much how akcapfit drew it. link

 

Certainly some of the problems are run of the mill fuel-filling problems. But there is an aspect to the fuel path of the Fit that relies on more than just gravity... and it probably is involved with at least some of the filling and capacity issues that come up.

My purpose in bringing up the issue was not to find fault with any aspect of the design -- but rather to find out exactly how the system works.

The interior design of the Fit revolves around the inter-relationship of its suspension and fuel tank location... and I suspect some fairly ingenious bit of problem solving to get fuel into the relocated tank.

I can't wait to see what we find out about how this actually happens.

(Steve244 had just posted his diagram while I was first writing this)
.
.
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I was curious about this too.

I don't even understand it. I mean, if your gas tank is near/under the front passenger seat, then why not place the gas cap/nozzle nearer to where it is, rather than to the reverse rear upper side?

 

Maybe to have that part of the tank as far away from heat/spark producing parts of the engine as possible? I don't know too much about car design, but I would think the 'traditional' design of having the fuel tank and gas cap toward the back of the car had to do with wanting the opening (and thus possible leaks etc) to be as far away from the engine as possible so as not to start a fire?

I don't know, that's just my guess. So you can move the tank itself but you should probably leave the cap in the back.

 

Good guess. They also want to put it someplace that is least likely to be damaged in a wreck resulting in spilled fuel.

 

I shoved my head under my car this morning and I'll be dipped, the refueling tube really does at one point run lower than the gas tank. Weird.

 

I wonder what anyone else has learned about this?

 

I'm in for finding out about this, too. Also, though, one of the benefits of the gas tank under the front seats is that it seems less likely to explode in an accident. I imagine if I were to be hit hard enough to ignite the fuel tank that's right under me I'm already dead, you know?

 

also remember safety from crashes and weight distribution.

 

Is the gas tank, the reason the under side of the front seats sticks out a bit? I always wondered why there is somewhat limited foot room in the front right corner of the drivers seat.