My Rotax Max is going bad, I’m doing pretty well, then I have to put the choke on a little, remove it and do another end. I play with the screws and even the gas cable, nothing to do. The fuel pump has just been reassembled, new spark plug and the air screw is 1/4 turn, like when I bought it, and even if I play with it, it’s worse. I know it should be between 1.5 to 3 turns based on what I’ve seen. Is it normal that the gasoline does not stay in the pipe between the tank and the fuel filter which is a little lower? Then after the filter, there is full gasoline up to the Carburetor. Sometimes the engine is fine, it pulls at maximum, but it doesn’t last long. Everything checked the carburetor too, everything dismantled, everything looks ok!, very clean, but I don’t know how it’s a needle that’s finished, if that’s it. Need your advice, thank you!
Had someone have a similar issue with the airbox being full of fuel. Floats were getting stuck in the carburetor. Also make sure your gas cap and fuel lines are well sealed. Just last night a buddies Rotax was running terrible like it was running out of fuel. Gas cap was cross threaded so the pump couldn’t pull a proper vacuum and suck fuel into the lines.
OK! THANKS. my floaters are ok! I checked them, but I will check at the fuel tank and cap, if there is no leak.
Try blowing air into the overflow line and see if you can hear any air escaping anywhere. That is how we found the issue last night. You could hear air coming out from under the gas cap.
OK! Thanks, that’s exactly what I wanted to try. Can I air from a compressor at low intensity. I imagine I have to block the outlet that goes to the gas filter, about 10 inches from the tank outlet. Is it normal that there is no gasoline in this section? From outlet to filter.
You can simply blow into the line. No need for air compressor. And yes just sitting there air can be in the line. When running the engine on the stand and applying the brakes to cause a load, you should see more fuel being pulled through the lines with less air. When it is just idling or not running you will see some air in the lines.
Just blow into the line with the small black cap (the one right next to the small red cap) and listen for air.
OK! Perfect, a big thank you! I’m going to try this tomorrow.
And you will tell me if you can, if it is normal that my air screw I believe, red arrow, is only 1/4 turn. I tried to play with it and it doesn’t work, sometimes worse. I read that it should be between 1.5 to 3 turns.
It’s a very small change that I never seem to notice. I have mine at 2 turns and leave it there for all conditions.
Have you checked the filter In the carburator? If its still In there throw it out, its bot unseen for that thing to be all clogged up.
The Airscrew needs to be around two turns out, we normally run 1 3/4 to 2 1/2 turns out.
OK! Thanks Clayton. I will try this
Merci ! Bjørn
Le filtre sur la ligne, près du réservoir, est neuf et oui j’ai enlevé celui dans le carburateur, il était fini et on m’a dis que ce n’étais pas vraiment nécessaire si on as l’autre.
Pour la vis d’air, à quoi elle sert exactement svp, ( air/essence ) je la sert au bout et je la déserre de 1.5 à 2.5 tours, 2 tours pour commencer, comme dis Clayton.
Extérieur: tu veux dire déserrer je crois
And there, nothing works anymore, it almost starts, but no longer wants to start.
My other question would be, because I seriously suspect that the carburetor has a problem, what do I need to change if I reassemble it, after having cleaned it completely with brake cleaner and passing the air through all the small holes. gasket kit, needle, I don’t know. THANKS !
when it doesn’t want to start…is the spark plug wet or dry?
Can you take a quick video? Best way to help.
Battery condition is critical too! Especially with the Rotax being a total loss system (I think).
A poor battery can show a good voltage when not under load, but fail to actually provide enough power when a demand is placed on it.
For sure continue to troubleshoot the carb as well but it’s not unfathomable that weak battery and slow cranking will cause fuel to build up.
This is correct, there is no magneto/generator onboard to keep it charged. His battery could be going bad.
If you can try starting it while the battery is plugged into the charger or swap out to a different battery.
Is your engine sealed? If not, you can pop off the reed cages and look at the front of the piston and make sure nothing bad has happened like a broken ring.
If it is sealed you can look in from the exhaust port for any signs of damage.
THANKS! and to you guys. That’s it I think, the spark plug is no longer good, I checked everything at the same time. Bizzard, because that’s still 2 candles that I burn in no time. A Denso Iw31 and an NGK BR10EG, both new. I have more, I just ordered some, with an official candle tester. So I’m going to be fixed during installation, and I’ll then see why. The air filter, the fuel pump, the carburetor all recleaned and adjusted, the fuel going well to the carburetor, piston check through the reed valve outlet, compression at 150 lbs and ignition coil check with another spark plug. Everything seems ok to me! same #1. Because the engine had just been rebuilt. Battery A1, new, starting at 14 amps. Starter #1 too. I will come back to you with the rest and the result. Another big thank you!
Also included how gasoline works. The line is full from the filter to the carburetor, almost no air, and gasoline rises to the filter from the tank, when the engine is running. We learn, that’s life.
One tip for Rotax gasoline: it has to be fresh. I used to stop at the gas station for fresh premium every day I ran the Rotax.
OK! Perfect, thank you Charles
I take careful note of this.