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Rotax 503 60 sec Idle
Posted: Sun Dec 15, 2019 3:18 pm
by Tango Bravo 1
My 503 in a T-bird 1 starts on choke runs until it loads up, re-start choke off, it runs about 60 seconds then just runs out of gas (apparently) then dies. When I check the fuel bowls they are more than half full. I have checked the carbs 3 or 4 times they look like new. This motor has about 3 hours on it. It is 20 years old though. I've tried to pump the squeeze bulb doesn't help. Really frustrating.
Re: Rotax 503 60 sec Idle
Posted: Tue Dec 17, 2019 4:58 pm
by Tango Bravo 1
What! No help? Surely I am not the only one to have this problem.
Re: Rotax 503 60 sec Idle
Posted: Tue Dec 17, 2019 5:19 pm
by drseti
Have you weighed the floats in your carb float bowl lately? They are a known Rotax problem area. Not sure what the floats should weigh for a 501 - in a 912, they should be 3.5 grams max per float (7 g per pair), with typical running 2.8 g ea.
Re: Rotax 503 60 sec Idle
Posted: Thu Dec 19, 2019 10:22 am
by Tango Bravo 1
I have not weighed them but they float high in the gas, and the bowl has fuel in it almost full when I take them off. Thanks for your response. I am trying everything I can.
Re: Rotax 503 60 sec Idle
Posted: Thu Dec 19, 2019 10:33 am
by drseti
When you remove the float bowls, the horizontal pin on the floats should be even with the surface of the fuel. If that's what you're seeing, then you can rule out the floats (and it's back to the drawing board).
The nearest Rotax 2-stroke experts to me are Bob and Lori Keech at Cloud 9 Aerosport, St Mary's PA. You might look them up and give them a call.