BOOSTER PUMP 2024 KTM Fuel Tank Issue Solution

BOOSTER PUMP 2024 KTM Fuel Tank Issue Solution

*OPIS PRODUKTU I INSTRUKCJE MONTAŻU PO POLSKU ZNAJDZIESZ W ZAŁĄCZNIKACH NA DOLE STRONY

KTM, HUSQVARNA and GAS GAS do not use all the petrol from the tank, 1.5-2 litres remain. This is a fact! Most of the fuel stays in the deeper left chamber of the tank. This is also a fact.
Riding enduro in the mountains, in the desert or as a tourist, this is a big obstacle.
Depending on the riding style, you could ride 20-30 km, but still the engine turns off.
This is due to the design of the fuel supply system and the place from which the pump in new motorcycle models draws fuel. The pump has been moved to the middle of the tank quite high, to a special chamber. The fuel flows into it as a result of sudden movements of the motorcycle off-road, but only for a while. Low fuel level slows down this process. Later, the engine starts to cut out, despite the fact that there is still fuel in the side chambers.

A cross-section of a 2025 KTM tank scan, from the front. In the middle is the blue central chamber of the master cylinder.

The side chamber is located 15 cm below the edge of the central chamber.
The fuel from the side chambers does not get into the central chamber. True!
The second problem that you may encounter is when the motorcycle turns off after a fall while lying on its side, or worse, on a slope with its wheels up.

The place from which the pump draws fuel will be emptied as a result of overflow into the side chambers. Starting a motorcycle that has no fuel in the central chamber (where the pump is located) immediately aerates the system.

I also noticed in my 500 EXC-F 2025 problems with starting the engine, for example after a long standstill, when the fuel tank is not filled enough.

These are the situations when, far from home, you can be helpless despite the small amount of fuel in the tank. It is there, inaccessible to the pump, there is too little of it to suck it up.
Putting the motorcycle on its side, borrowing fuel from friends, may not be enough either. You should get the fuel into this small central chamber where it will be sucked in by the main pump. But how to do it?

It's not easy. You have to pour in enough fuel so that the bottom of the pump is below the level. The battery is only 2Ah, you don't have much chance of starting it. With each subsequent attempt the starter has less energy.

The KTM fuel pump can only lift fuel from about one inch below its own rim when not "wet" so changing the fuel pickup point with an "additional hose" won't always work, and you need a reliable system.
I was the first to test this idea, with high expectations. Mike from Taco Moto also experimented with this (now I see the Chinese are selling it).
Unfortunately it's a dead end, it doesn't work reliably. Check out this test prototype (pictured below). There's a filter, a valve at the bottom and a magnet to hold it in place. Half a year wasted on thinking and testing.

All I had to do was put the pump in the container and learn the truth about how it works. A dry pump does not suck fuel below a certain level. For this to work for sure, the lower edge must be below the liquid level.

https://www.youtube.com/watch?v=lmgE_41UY8Y

The photo above shows exactly the moment from what height and when the fuel is sucked in by the fuel pump, it is not yet flowing out of the overflow (the pump is "dry").

A moment later, fuel is drawn from the level below the pump (the pump is "flooded"). The entire time the pump is working in this way, there is a very unfavorable phenomenon of air on the rotor, foamed fuel.
This is cavitation, the killer of pumps.
How is the pump supposed to draw fuel from the bottom of the left chamber? How?
But now we have a Booster Pump!

Schematic diagram of the BOOSTER PUMP operation (first stage pump) schematically marked on the tank.

In fuel supply systems, it is normal that an additional first-stage pump is needed, basically as it was in KTM so far, or in "Dakar" vehicles with several tanks, it is nothing new. Why was this proven solution abandoned? Simple, the entire fuel pump assembly with filter and pressure regulator no longer fits in the left chamber, it is too narrow to fit it there. Remember that this extended assembly of the pump, large fuel filter and lines also took up volume, displacing fuel.

BOOSTER PUMP by ET-Racing what is it?

First of all, it is plug & play.

It consists of a metering nozzle attached to the main pump housing just above the fuel filter and an additional pump attached through a single hole drilled in the bottom of the tank, exactly the same way that pumps have been attached to KTM tanks for the past 23 years. Screwed with the same nut and sealed with the same proven O-ring.
The booster pump is plugged into the main pump circuit with connectors on the housing.

How it works

The Booster Pump fills the central chamber where the main pump is located. If you have fuel in the left chamber, it will be delivered to the place where the main pump will draw it from. Simple and reliable, right?

Fuel filter at the bottom of the central chamber.

This is what the central chamber looks like after removing the main pump and fuel filter. This is where the fuel pickup point is.

If you are really low on fuel and want to use up the last bits, you can lay the bike on its left side, wait for everything to drain into the left chamber, lift the bike up and start it.
-The moment you press the starter button, the Booster Pump will immediately fill the central chamber with the last bits of fuel! We mean the last drops!


See how precisely and accurately the Booster pump nozzle delivers fuel to the fuel draw point. It is delivered only to where the main pump will immediately suck it up.

How is the pump controlled?

-Booster Pump does not work continuously, it is pulse-controlled.
-It uses the signal from the fuel sensor thermistor and the motorcycle fuel indicator light.

-The microprocessor system constantly monitors the amount of fuel in the tank, switches on the booster pump power supply before the fuel level reaches the reserve.
-For proper operation, it needs information from the front wheel speed sensor.

Important! In the event of a speed sensor failure, the microprocessor system of the Booster Pump controller will pump fuel regardless of the amount of fuel in the tank.

This is not harmful, but the Booster Pump will draw 1.6A in a pulsating manner, every few dozen seconds. This is not much (the fan draws 4A as soon as it turns on) but it is important that you have this knowledge.
That is why we recommend having a working front wheel speed sensor (a spare is available in our store).


The last photo shows how a special nozzle doses fuel precisely onto the filter so that it is immediately sucked in by the main pump.

You don't have to do a wheelie when the bike starts to stop (but you can still do it) :)

Weight 260g

Also fits larger capacity tanks (ACERBIS).