[Court93kat]

Double-walled gas tank? Huh?

Cheers,
=-= The CyberPoet

That's what I was thinking. New one on me.

[TheSteve]

Sorry for the lack of updates today, I've been helping my friend pull the engine out of his truck. I rearranged the fuel lines so the FPR is on top of the valve cover. This places it about an inch or so above the fuel rail so air can now escape. Also drilled a hole and installed a hose barb in the fuel level sender, next to the sending unit. I haven't been able to test it, I'm waiting on more JB weld to dry to seal the barb. For the gas tank vent I might drill a very small hole in the top of the tank underneath the gas cap assembly. If I can find a check valve this should still seal the fuel in even if the bike is dropped yet allow for air to enter the tank.

1SikKat, are you SURE about the double walled tank? Looking inside it sure looks like a single wall. I think I'll just stick with my idea for now. Less chance of messing it up beyond repair.

I did measure the fuel sender hole for you Court, the hole itself is 1 1/2". If you want the diameter across the bolt holes I can get that too. If you can find an in tank pump, that IS the way to go. Makes plumbing much cleaner. I had the GSXR pump measurements somewhere, I'll see if I can dig them up. All I remember offhand is its too big by a fair margin.

Tomorrow (or maybe even tonight if the JB weld is dry) I'll reinstall the level sender, throw the tank back on, finish rerouting the lines, and see if it helps with reliability.


Ah, here we go. GSXR fuel pump is 2 3/8" with a 4 1/4" flange.

Lastly, here is a diagram comparing the new fuel line routing to the old setup:




In addition to the FPR being relocated, the 3 way fuel filter is gone. As I half expected, the recirculated fuel is getting way too hot. The filter would damn near burn your hand! I also suspect that this was causing the fuel to evaporate in the lines, causing air bubbles to block the injectors. It was replaced by adding a second hose barb into the tank itself, allowing the fuel to cool sufficently before making its way through the pump again. I mentioned doing this a few pages ago, but decided to take the lazy way out. As expected, I'm paying for it now.

[1SikKat]

Think about it....how are there holes already in the bottom of your tank without it leaking gas?? Seems like it only makes sense to me...If I splash gas around the fill hole (not on the outside, the little lip) it drips out of the bottom of the tank...Maybe I'm just crazy.

[TheSteve]

I got the katana running today, sort of. Its still giving me some trouble starting up and it dies after about 30 seconds. While cranking it seems to be running lean but once started its rich off the scale, past 8 to 1 afr. The engine cuts out before I can lean it out. Its close and everything works now, so its just a matter of tuning.

[1SikKat]

Sounds good!!

[Newbie2it]

Think about it....how are there holes already in the bottom of your tank without it leaking gas?? Seems like it only makes sense to me...If I splash gas around the fill hole (not on the outside, the little lip) it drips out of the bottom of the tank...Maybe I'm just crazy.

Let us know how this works out for you when you drill a hole through your "Double walled" Kat tank. I, along with just about everyone here on KR would like to know. I'd be glad to know my Kat's built as solid as the Exxon Valdez

[TheSteve]

Think about it....how are there holes already in the bottom of your tank without it leaking gas?? Seems like it only makes sense to me...If I splash gas around the fill hole (not on the outside, the little lip) it drips out of the bottom of the tank...Maybe I'm just crazy.

If you remove your gas cap (whole assembly) you'll see theres a small hole near the actual filler hole. If you look into the tank, easier while empty, you'll see theres a thin pipe going from that hole at the top to a spout at the bottom (probably connected to the airbox or something on a stock bike). If thats your only evidence to the tank being doublewalled I can assure you that it's not. If there was something else that leads you to think it is than it's still..possible. Still not likely, but I can tell you that the reason it drains when you get gas around the filler is because of that little tube.

[TheSteve]

I think the reason I'm having so much trouble with getting this started is the lack of an intake manifold. When I MS'ed the truck, it had a nice steady vacuum signal for the MS to use. But with 4 individual throttle bodies, while cranking theres barely any vacuum at all at low rpm, even with the throttle closed. I could be way off here, but when I put the MS on the truck (with spark control thrown in the mix as well) it started up with just a bit of tinkering. The katana on the other hand is giving me alot of trouble both on starting up and staying running. Alot of this was the completely redesigned fuel system. Problems were bound to happen there so I wasn't fazed at all but this is being quite tricky now.

Now that the fueling system all works I think I need to throw out my current tune and start fresh making sure everything is configured correctly and all bandaids have been removed. Unfortunately the wideband can't really aid in finding cranking pulse widths so alot of the startup problems exist due to bad estimation. Once the engine will hold an idle the rest of this is easy. Getting that first start in is the hardest part.

For anyone thinking about doing this as well, don't worry about all this trouble I'm having. Once the initial tune is made I'll post it all up for download so this is pretty much plug and play. You'll still need to tune it yourself for your specific engine and mods but it will be close enough to start it without difficulty.

[Genkenx2]

I'm cheering you on man. I love this thread and I always come on to the site hoping I'll read a post from you in victory.

Keep it up, and keep on updating us. I want to see this thing come to life.

[1SikKat]

Maybe it was just those 2 or 3 Honda tanks that I cut up when I was younger (patches for my old Baja Beetle)....who knows? But, since venting is not the problem here, there is no need for extra vents...

[TheSteve]

Posting from cell phone again so please pardon typos. Great news today, got the bike to start easily and idle smoothly. There was a glitch in the ms code causing it to cut the gas off after 2k rpm. Its idling high, around 2300 but the idle mixture needs adjustment still. I should be able to take it for a spin around the block tomorrow. My roommate got a video of it running, ill post it tonight sometime.

[Court93kat]

Congrats Steve!! Keep up the good work, man!
:mrgreen:

And for all of you who said "It'll never work", "too much work", etc

[Astro4x4]

Congrats Steve!! Keep up the good work, man!
:mrgreen:

And for all of you who said "It'll never work", "too much work", etc

+1
Now throw a turbo on that bad boy when you are at it:mrgreen:

[TheSteve]

Hehe I like your thinking. But the turbo would probably wait til a 750 or 1100 swap. Now that would be something to see

[1SikKat]

Sounds like some good progress!!! Keep at it man.