small engine fuel issuse

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matman55

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Hey, i have a little 80cc 4stroke yamaha engine, and i cant get it to run. It will start on starting fluid and run for a few seconds depending on how much i spray. It will not run on its own will out the fluid. so that tells me its a fuel not geting through the carb issue. ive replace the intake seals and got a new sparkplug. so what should i do next? ive never delt with something like this before and i dont know what to do next. please help!
 

Doc Sprocket

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Follow the fuel. Pull the fuel line off the carb, point it into a suitable container, turn the fuel tap on. If it runs fairly freely, then there's no problem there. Connect it to the carb again. Put a catch pan under the carb, and remove the drain bolt (if equipped) bowl bolt, or remove the whole bowl. If fuel runs freely, then it's good. Now put that back together. Clean and dry the spark plug, and reinstall. Roll the engine over several times with pull starter, kick starter, or electric starter, whatever you've got. Pull out the spark plug. If it's damp, and there's a good fuel odor from the cylinder, then you're good there. If it's dry, clean your carb.
 
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matman55

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:roflol:everythings good, im on a short break again.

so,the two jets are clean, so is the rest of the carb. fuel is not flowing but driping from the fuel line at afast rate,ill blast out the peatcock and see if the does it. ill go out later and try the method described by toystory,thanks!
 

matman55

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ok, so i tried toystorys method and the spark plug is dry as a bone. "ok,so no fuel is getting past the carb" i said. next i went on inspecting the petcock,long story short it turned out i didnt have enough fuel in it for a constant flow. so the tank,petcock,fuel line is all free flowing. would that mean that something is up with the carb? the carb is compleatly clean and the float is working correctly. i know the carb works because it can run off of starting fluid. im stuck and frustrated! help!


edit: and yes, im using clean fuel!
 

SpeedBoy

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have the gas off or tilt the thing so no gas is getting to the carb and take the bowl off. Next hold the float up and turn gas on or tip back so gas can get to the carb. Then let the float down a bit and if gas comes out like it should that would mean there is a issue with the jet in some way.
 

Kaptain Krunch

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You dont know the carb works because it starts on starting fluid. spraying starting fluid in the intake will make an engine run even if the carb is completely clogged. Clean the carb make sure everything is clear and moving as it should (mainly float, but check the slide too).
 

Doc Sprocket

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You dont know the carb works because it starts on starting fluid. spraying starting fluid in the intake will make an engine run even if the carb is completely clogged. Clean the carb make sure everything is clear and moving as it should (mainly float, but check the slide too).

Precisely. Frankly, you don't even NEED a carb on the engine to run on ether (starting fluid). You can test an engine with no carb at all by spraying the stuff into the intake.
 

matman55

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There is some pitting on the inside of the bowl and i still cant get it to work. Given that the carb is from 1986 i think its fair to say i need to buy a new one. To bad a new carb costs 400$.
 

SpeedBoy

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Only other thing i can think of is leaving the carb soak in WD40 in a cup for a couple of days and see if it cleans something out on it that may be causing trouble.
 

matman55

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ill try that. if that dosnt work ill put a lawn mower carb onto it and ride it till it brakes again. its old and not really woth the time or money. aslong as it runs for a little bit and i can get some enjoyment out of it im happy. after that i could part it out or get a new motor for it and make it go redneck fast!yeeeeeeeeeeeeeeeeeeeeeeeeehaaaaaaaaaaaaaw!!!!!
 

devino246

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It's very rare that you actually have to replace an entire carb. Usually only if part of the carb body is broken or worn. Have you taken it apart and let it soak over night in carb cleaner? Blown out all the passages? Removed the bowl with the fuel line attached to see if you're getting gas into the bowl? Checked the float height? Purchased a carb kit and rebuilt the carb?
 

matman55

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Ive blown out all of the little holes, jets, and cleaned it. Ive yet to soak it. And if that dosnt do the trick ice decided to use a old dune buggy carb. Rather that the one from the lawnmower.
 

devino246

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Ive blown out all of the little holes, jets, and cleaned it. Ive yet to soak it. And if that dosnt do the trick ice decided to use a old dune buggy carb. Rather that the one from the lawnmower.

You didn't answer any of my other questions, but you know that you're going to have to rejet a new carburetor, right?
 

matman55

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whoops,nevermind. my friend came over today. took of the fuel petcock. and wolla!the fuel filter was cloged and barley let enough fuel through. so i orderd a new one along with some seals. ill letcha guys no how it turns out! later.:oops:
 
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