Going from gravity fed to a fuel pump?

[dman10]

Buddy and I are building a drift trike using a 200x engine(engine is removable in case a future project comes up for it) and with the design we can't mount a tank over the engine. Can we put a inline fuel pump on it? Worried about giving it too much fuel or too little.
Thanks,
"D"

[El Camexican]

I spent some time looking for an adjustment for my Tri-Z pump which uses a vacuum pump.

I found the problem and didn't have to mess with it, but my idea was to put a small adjustable brass valve in the fuel line just past a tee that would divert excess fuel back to the tank. I assume you're looking into an electric pump which should work with the same set up, but I never did find a valve that was small enough to fit a fuel line and was of a quality suitable for fuel emersion.

The 91-97 Ducati 900's use a submersible fuel pump that you could put in whatever tank you use. You can find them used for under $40 bucks on eBay (I pick one up for $26 bucks). Now that I think about it the Ducati petcock is an aluminum needle screw that might serve for your valve. On the Ducati 900 the float seats have enough resistance that the bleed back to the tank is enough to keep the fuel pump for over powering the float seat. You may get away without a valve to create additional resistance.

Whatever you do keep posting, it sounds like a cool project. :beer

[Trackburger]

Id think youd need to have a flow divider on the supply side to the carb that would divert excess fuel back to the tank like a "recirc" mode. The Honda Odyssey FL350's and Honda Pilot FL400's have this. The pump flows a set amount that is more than what the engine/varb set up would need to prevent running the bowl dry...any excess just goes back to the tank. Not sure how you could set this up with the 200X though.... There are certain flow rates that you will need to know to ensure you are in fact getting enough. Also.... too much pressure could cause you to blow fuel out the carb overflows. The FL350 and FL400 were 2 srtrokes, so they used a pulse vaccum pump driven off crank case pulse pressure...You would have to set up an electric pump on yours.

[Toaster556]

If it was me I'd run a standard vaccuum fuel pump like Suzuki did on the ALT125/185. The 200x manifold is long enough to have a fitting tapped in, and the vaccuum signal should be strong enough to run it.
FWIW, Kawasaki did the same with the KLTs, and mower racers run them with big HP v-twins with no fuel supply issues.

[AK47KID]

You could use a small garden tractor fuel pump... like JohnDeere

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[RIDE-RED 250r]

I just did some carb work on an '86 Fourtrax 4x4 350 for a friend. These quads have an under-seat fuel tank and thus a fuel pump. This quad runs a carb that it nearly identical to the 350x carb with a few minor differences.

Now the pump on this quad is electric and you can hear it click when it sends a little shot of fuel as the carb calls for it. Pretty cool how it works actually...

Thanks to El Camexican helping me to make a Tri-Z run a PE34 a couple years back and learning that in alot of carbs that are fed by vacuum pulse pumps, the fuel metering needle and seat are smaller so the pulse pump does not overpower the float and metering valve and cause fuel to just run out of the overflows when the engine is running. If you try to run a carb that was designed to run on gravity feed this will happen unless you do as El Camexican suggested above and run a "T" fitting with a bypass line back to the tank.. This method worked on that Tri-Z. I never knew there was a difference in metering valve size based on whether or not the carb was to be run on a fuel pump or gravity...

Now that I said all that, this brings us back to the TRX electric fuel pump. I ended up selling my friend my stock 350x carb. Long story but I won't digress from the topic at hand. Anyway, I compared the metering valve sizes between the OEM Foutrax carb (fuel pump fed) and my OEM 350x (gravity fed) and found that they were exactly the same size.. It was then that I put 2 and 2 together and figured out that this little electric pump is "smart" and only pumps fuel when the metering valve in the carb calls for it. There must be some type of regulating valve inside the fuel pump that the metering valve in the carb can hold back.

So after saying all of that, I would say that a fuel pump from one of those old 350x engine powered Fourtrax 4x4's might do the trick very easily and simply as long as you can power it with 12v. My friend actually just replaced that fuel pump as he was trying to diagnose his problem before having me work on it, pump only cost him about $20.

[RUNMEDOWN]

use an electric pump, use a simple "T" line split to run one line to the carb and the other back to the tank for over pressure. Put a jet inside the return tub to add back pressure, I used a 110 jet and it worked great.

[NeverLift]

http://www.ebay.com/itm/Fuel-Pump-FOR-Polaris-Magnum-325-2000-02-Sportsman-600-2003-05-Outlaw-450-09-10-/311468291731?var=&hash=item4884f4f693:m:mfgQS4iUYWddwsoNu1LnsrQ

I just replaced a fuel pump on some POS Polaris. This is the one i ordered and it works mint. Tap a fitting in your manifold for the pulse line. Add a T fitting to your carb supply line, then route this return line to the top of you tank add a fitting there and away you go. Without this the pump will overpower your float and needle and you'll be dumping fuel everywhere.

[RIDE-RED 250r]

This is the pump my friend got. I doubt you would need to run a return to the tank.

http://www.amazon.com/TRX350-Fourtrax-Replaces-16710-HA7-672-1986-1989/dp/B00M5DYGSC

[NeverLift]

This is the pump my friend got. I doubt you would need to run a return to the tank.

http://www.amazon.com/TRX350-Fourtrax-Replaces-16710-HA7-672-1986-1989/dp/B00M5DYGSC

This is the way to go. PSI regulator built into the pump, no return line. Lets see a picture of this damn thing.

[El Camexican]

Thanks to El Camexican helping me to make a Tri-Z run a PE34 a couple years back and learning that in alot of carbs that are fed by vacuum pulse pumps, the fuel metering needle and seat are smaller so the pulse pump does not overpower the float and metering valve and cause fuel to just run out of the overflows when the engine is running. If you try to run a carb that was designed to run on gravity feed this will happen unless you do as El Camexican suggested above and run a "T" fitting with a bypass line back to the tank.. This method worked on that Tri-Z. I never knew there was a difference in metering valve size based on whether or not the carb was to be run on a fuel pump or gravity...

I do love being scratched behind the ears as much as the next cat, but I can't take credit for this info. I believe it was zmpolaristec that was the one who enlightened me on this topic.

[RIDE-RED 250r]

And you passed that knowledge on to me, which helped me out immensely! You deserve to have your ear scratched now and again. :beer

[dman10]

231707
We're gonna try a vacuum pump first. We're already gonna have space problems, don't wanna try fitting a battery also.
We're at a stand still waiting for the rear axle.