EFI in an ATV...

[hydromike]

So I completed the install of the 26-horse Kohler EFI engine in the Chief this year. It performs great. I'm dealing with a serious deal-breaker of an issue on the machine, and I need ideas.

The EFI system operates on about 45psi of fuel pressure on the pressure side of the regulator to the fuel rail. I'm getting air in the system from the pickup inside the tank. Air in an EFI system equals bad. When the air gets in the system, the air "bubble" gets caught in the top part of the fuel rail (it's an arch b/t the two injectors), so one cylinder gets appropriate pressure, but the air in the system gets caught here, and forces the front cylinder to run lean. Effing lean. The muffler will turn red. A bad thing. There is a bleeder at the top of the rail, but it never gets all the air out, and eventually more air will work its way into the system. There is a recirculation line on the opposite side of the pressure regulator that moves unused gas back to the tank. Now, this puppy isn't a little spit-spit pulse pump. You could water the friggen' lawn with this baby. If air gets anywhere close to the pickup, it'll get sucked into the vortex that is my 0.5 gpm pump. A bubble stands no chance of getting back into the tank once it's in the pickup, unless it goes through the whole system. That's not good.

Everything else is sealed (i.e., it's not sucking air from a loose fitting) as the pickup line is getting sloshed around in the tank, it eventually picks up itty bitty bubbles, which eventually congregate in the rail. To make a long story short, I need a way to set up a fuel tank and pickup where there is (key point here) NO POSSIBILITY of getting air in the system. I've thought about it for months. Round tank with central pickup? No good, it'll still pickup air if it gets sloshed around.

I need good ideas. The machine is useless unless I can use it for what it's intended for.

Thanks in advance...
~m

[fire 6x6]

Maybe you could get someone at RI to tell you how they solved that problem. They started putting the kawasaki fuel injected motors in the max 4. I am not sure if the kohler and the kawasaki use the same fuel systems or not.

[jpswift1]

Mike, I am no expert at all with EFI systems, but do you know if any of those guys running the rock crawling rigs run EFI? If so, maybe they could help you with the issue. I know that one of my friends from Georgia who runs rock crawlers converted his rig to propane so it can run at extreme angles. Would the type of fuel cap have an affect on your system, sealed VS vented? I'll talk to a few of my friends and see if they can help with EFI issues. Until then I'll keep thinking. Good luck!

[Roger S]

Could you use the bleeder tap with a tiny jet to continuously bleed off into the return fuel line

[whipper-ag]

First off Mike, is your fuel pickup in the very bottom of the tank or off to one side? There is some stuff that a lot of racers & duners use to stop the sloshing of the gas. It's like a big coarse sponge & you just stuff it in the gas tank & on top of the pickup so the pickup tube can't bounce around. I can't remember what it's called, but I will find out & where to get it. I kinda don't think that's your problem though. It's got to be sucking air from somewhere. What kind of fuel fittings are you using on the fuel pump, filter & fuel rails? I don't think rubber hoses & clamps are sufficient for a system under pressure. I'll keep thinking about it.

Whipper

[jpswift1]

First off Mike, is your fuel pickup in the very bottom of the tank or off to one side? There is some stuff that a lot of racers & duners use to stop the sloshing of the gas. It's like a big coarse sponge & you just stuff it in the gas tank & on top of the pickup so the pickup tube can't bounce around. I can't remember what it's called, but I will find out & where to get it. I kinda don't think that's your problem though. It's got to be sucking air from somewhere. What kind of fuel fittings are you using on the fuel pump, filter & fuel rails? I don't think rubber hoses & clamps are sufficient for a system under pressure. I'll keep thinking about it.

Whipper

Mike, Whippers post just gave me an idea. Maybe you could make a custom fuel tank with baffles welded in it to prevent the sloshing of the gas.

[Beeman]

I agree with wipper... the air is probably coming from somewhere other than the tank. But... if so,

- Modification of the tank to have a deep pickup (ie.. a pipe entension down where the pickup could be extended to).
-some sort of gas sloshing buffer (as explained by wipper)
-an air seperator upline near the carb

[Mike]

Mike, does it do fine if your tank is filled ALL the way up?

[hydromike]

Ah, this is exactly why I posted. THE FOAM! I just got rid of a couple different fuel cells with the foam, and I didn't even think about it this time.

I'm using fuel injection clamps on all of the lines. It's really (really) not sucking air past any fittings. It will sit still and run for ever w/o developing fuel bubbles. If I take the machine and violently shake it forward and backward while it's sitting there runing, it'll get bubbles in the lines. I can see the pickup sloshing in the tank. Then it starts missing on one cylinder as soon as the system loses pressure and starts trying to compress air. The darn thing just moves so much darn fuel that it sucks in any/all bubbles. I'm trying the foam. I can't believe I didn't think about it. Baffles would be a good idea, but even then, it'll slosh around some. Foam eliminates this almost entirely. (why didn't I think of the FOAM). Thanks to all for all of the very fast responses.

I'm gonna quadruple check fittings (again), too.

Foam me, Sammy..
~m

[hydromike]

Mike, does it do fine if your tank is filled ALL the way up?

It doesn't happen as often. Then again, I've never had it full past the pickup, because there's a slow leak by the pickup. This makes for flammable sneakers....

... which is an AWESOME name for a band..

~m

[Mike]

This makes for flammable sneakers....

... which is an AWESOME name for a band..

~m

[whipper-ag]

I think your car is sponge worthy. Hope that's it.
Whipper

[Beeman]

makes for flammable sneakers....

... which is an AWESOME name for a band..

~m

I don't know... sounds kinda... hmmm

Politically correctness would make me state that I appreciate flame retardant sneakers.. :P

[hydromike]

It's TOTALLY Sponge worthy! I'm a dolt for not thinking of this.
The rest of the fuel system is plumbed just as it was off the piece of power equipment. The thing with the pickup in the tank is that' I'm using a piece of poly fuel line inside the tank, since the pickup is mid-way up the side of the tank. It's weighted down really well, and all the clamps are the correct styel (not hose clamps, they're the right Kohler-spec high pressure clamps, even on the low pressure side). The fittings on the inlet and outlet side of the pump are stock Kohler spec parts with the same fittings. Nothing's changed from the piece of power equipment it came off of. It was in JoeH's former machine, and he didn't have problems. As far as I know, he was using a similar setup, but I know I'm going to be more-stupider stuff with the machine. It likes to be vertical, but the fuel pickup doesn't like it that much. slosh-slosh, bubble-bubble

Sponge me, Sammy...
~m

[Little Rhody]

Mike, I tend to do things a bit differant than others, and I tend to be a bit exsessive, but when I designed my fuel system, I built two two tanks, The first tank that houses the filler neck and fuel gage feeds the second tank. The second tank feeds the motor, and the return line from the motor goes back to the the second tank. Any excess from the second tank returns back to the first tank via a return line. This allows the second tank to be full all the time, so you could have a half a tank in the first tank and sit on a hill and for prolonged periods of time and never run the motor out of fuel. Also the second tank acts as a reserve. Ie: if the gage say "E" you still have the ammount left in the second tank to run on safely.