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air bubbles in fuel line

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Old 03-13-2010, 02:22 PM
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sdnitro
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Default air bubbles in fuel line

I just purchased a redcat racing earthquake 3.5. I am having trouble with air bubbles entering the carb. When a bubble enters the nitro engine will quit at idle or bog when trying to accelerate. I usually have to prime the engine when I restart it. I used plastic wire ties to try to seal up the rubber fuel lines on their fittings. I used teflon tape on the fitting on the fuel tank to seal the threads. The engine is broke in. I am sure there should be no air in the fuel line from the tank to the carb. Any suggestions would sure help THANKS
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Old 03-13-2010, 02:49 PM
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Default RE: air bubbles in fuel line

Take the zip ties off the ends of the fuel line. Get the teflon tape off the nipple threads. Then Check your fuel lines for pin holes by taking each one off and submerging it in water, plug one end and blow in the other end and look for bubbles, flip it around and do the other end. Do that with both lines. If no bubbles, connect the lines back to the fuel tank, plug the end of the fuel line going to the carb and blow gently into the line that goes to the exhaust. If the fuel tank cap is good it should hold some pressure. If it leaks or the top pops up too easily, then the fuel tank is bad. If the tank is good, then put some fuel in the tank and (with the carb end disconnected) gently blow into the end that goes to the exhaust and fuel should come out of the carb end easily, if it's hard to get fuel to come out, then you have a piece of plastic stuck in the pick up line INSIDE the tank, means the tank is bad. The plastic sometimes gets pushed to the back corner when they thread the fuel line nipple into the tank. If all that worked out, then check your exhaust gasket isn't blown out or that the manifold screws are not loose. If that,s ok, then check the exhaust coupler to make sure it's not leaking, replace the factory Zip ties with the 1/8 or 1/16th wide black zip ties and pull them as tight as you can, if you haven't already done that. Check to make sure there's no tears in the exhaust coupler. More than likely one of those mentioned above is the problem.
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Old 03-13-2010, 06:30 PM
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Default RE: air bubbles in fuel line

Excellent post
More then anything else these have been the problems with my RC's
DOUG
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ORIGINAL: AllAboutFunHobbies

If all that worked out, then check your exhaust gasket isn't blown out or that the manifold screws are not loose. If that,s ok, then check the exhaust coupler to make sure it's not leaking, replace the factory Zip ties with the 1/8 or 1/16th wide black zip ties and pull them as tight as you can, if you haven't already done that. Check to make sure there's no tears in the exhaust coupler. More than likely one of those mentioned above is the problem.
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Old 03-13-2010, 06:57 PM
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Default RE: air bubbles in fuel line

Thanks Doug, Long time, no see. How's it going?
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Old 03-13-2010, 08:49 PM
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Default RE: air bubbles in fuel line

Not much RCing,the winter up here in NYS has been horrible
DOUG

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Thanks Doug, Long time, no see. How's it going?
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Old 03-14-2010, 11:46 AM
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Default RE: air bubbles in fuel line


Quote:
ORIGINAL: codokas

Not much RCing,the winter up here in NYS has been horrible
DOUG

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ORIGINAL: AllAboutFunHobbies

Thanks Doug, Long time, no see. How's it going?
Ya it's been a harsh winter here in Texas, believe it or not. It's almost time for Rcing weather up there.
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Old 03-14-2010, 01:18 PM
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sdnitro
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Default RE: air bubbles in fuel line

Thanks for the advice.  After a short inspection I discovered that my fuel line from the tank to the carb had a hole rubbed in it from the drive sprocket.  I did not have another fuel line but i did have a plastic splice that was used in a air bubbler from an aquarium.  I was not sure if the air line from the aquarium would work with fuel but im sure the splice will hold up until i can replace the fuel line.  When you live along ways from anything its nice to improvise if you can get away with it.  Well anyway the truck runs just great and im glad it was an easy fix
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Old 03-14-2010, 02:56 PM
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Default RE: air bubbles in fuel line

Buy bulk fuel line. It's usually pretty affordable, and sure beats buying it at inches to 3 feet at a time.
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Old 04-06-2011, 05:29 PM
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