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back flush carburator

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Old 06-03-2014, 11:31 AM
  #1  
fredsedno
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Default back flush carburator

Gentlemen,
I'm certain this question has been asked before: how do I back flush the carburator
on a OS 46 AX engine? I pressure tested the fuel lines [2 line setup] they show no
obstructions or splits. The tank itself doesn't have any issues. The engine will not start.
Can't get any fuel to the carb. Glow plug is new and does glow orange/red.

Thanks in advance, fredsedno
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Old 06-03-2014, 02:52 PM
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R8893
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Disassemble and clean individual parts.
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Old 06-03-2014, 07:33 PM
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Gray Beard
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Agreed, I have one of those ear flush bulbs I use quite a lot though. It has come in handy very often, more so with gas carbs but I have also discovered leaks in the case by attaching it to the carb and sticking a thumb over the carb and giving it a squeeze. Some engines have a steel insert press fit into the case and I have discovered a leak around the insert. I have also pulled trhe needle valve completely out then hooked the bulb to the main nipple and cleaned crap out of the spray bar.
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Old 06-03-2014, 07:55 PM
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1. Take off the carb
2. Attach fuel pump to carb inlet
3. Put carb in a water glass.
4. Crank like you've never cranked before. Try to stop before the glass overflows.
5. Crank the other way like you've only cranked once before just recently.
6: Repeat as needed.
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Old 06-04-2014, 05:39 AM
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Will it suck fuel while you prime it?
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Old 06-05-2014, 12:03 PM
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fredsedno
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jetmech05

No, it doesn't suck fuel after priming.Engine sometimes burns up prime then quits. This leads me to
suspect a problem with the hs jet.
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Old 06-06-2014, 06:29 AM
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jester_s1
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Technically speaking, there are no jets on RC carburetors. There's just a little hole in the spraybar that the fuel comes out of. But you may still be on the right track with suspecting a blockage. More often than not though, an engine that won't pull fuel when being primed has an air leak somewhere.
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Old 06-09-2014, 05:18 PM
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tacx
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You say you pressure tested the fuel lines. How exactly did you do the test?

Did you take the lines out of the tank?

If you did not and you just pinched off one line and blew air into the other line to pressurize it, while both lines were still in the tank, you have accomplished nothing except check the tank itself for a leak. If this what you did then you may very well still have a split in the pickup line and are sucking air from inside the tank. Take the lines out of the tank to check them.
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Old 06-12-2014, 11:00 AM
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perdo
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Open the needle valve more and see, if it will draw fuel. And also check the pressure vent on the muffler it might be stopped up, I had that happen on a new engine and like to have never figured it out.
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Old 06-18-2014, 05:23 PM
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Edwin
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On a suspected carb blockage, I first spray wd-40 into the carb fuel nipple. If it doesn't flood out, the carb comes off, pull the barrel out, then wd-40 again. It should blow anything out the opposite end. Check the spray bar opening for any blockage. Spray into the barrel low speed plug to clean out any scum. Reassemble and test with wd-40 again, it should flood through easily. Works for me.
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