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28cc Gas engine not getting fuel? Help please? i have not clue

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28cc Gas engine not getting fuel? Help please? i have not clue

Old 03-22-2010, 02:44 PM
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Neb_16
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Default 28cc Gas engine not getting fuel? Help please? i have not clue

I have converted a 28cc Ryobi chainsaw engine for use in my Giant Big Stik. The engine only had a couple of hours on it and has excellent compression, bright spark, etc. It sat for a few years before I tried to run it and sure enough, it wouldn't start because it wasn't getting fuel. So I did the normal carb cleaning and what not and still, no fuel. I also tried replacing the fuel lines with no luck. Eventually, I borrowed an identical walbro carb (which I knew to be working) off my chainsaw. I put it on the rc conversion engine and still, no fuel! The funny thing is I immediately put the carb back on the chainsaw and it fired right up! So to make a long story short, the engine is not getting fuel despite a working carb and clean fuel lines... What else is there? It does fire right up when I spray starter fluid in the carb but then dies soon after due to burning off all the fluid. This just has me baffled. Could it be bad reeds or something?

P.S. Having come off a chainsaw, there is no pressure line... Just one fuel line running from the fuel tank to the carb. Thats is.. Any advice?
Old 03-22-2010, 03:00 PM
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Lnewqban
 
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Default RE: 28cc Gas engine not getting fuel? Help please? i have not clue

Is the hole (that can be seen on the carb flange) taking pressure from the crankshaft open?
Old 03-22-2010, 03:06 PM
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Steve Percifield
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Default RE: 28cc Gas engine not getting fuel? Help please? i have not clue

Can you post a picture so I can see if it's side intake or rear intake. If it's side intake, I believe you have not aligned the carb mounting block correctly. The carb must sense the pulsing of the engine crankcase pressure to activate the pump. There is a small openning in the carb, that must line up with the openning in the mounting block for this to happen. Zenoah offers a carb rotation kit and I have seen many guys install it incorrectly with the openning blocked and their engines do the same thing until the opennings are aligned. The carb simply doesn;t pump fuel.
Old 03-22-2010, 03:07 PM
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ChuckW
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Default RE: 28cc Gas engine not getting fuel? Help please? i have not clue

Are you sure the clunk and line in the tank are good? This stuff gad go bad over time and develop holes or collapse, etc.
Old 03-22-2010, 05:36 PM
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Gray Beard
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Default RE: 28cc Gas engine not getting fuel? Help please? i have not clue


ORIGINAL: Steve Percifield

Can you post a picture so I can see if it's side intake or rear intake. If it's side intake, I believe you have not aligned the carb mounting block correctly. The carb must sense the pulsing of the engine crankcase pressure to activate the pump. There is a small openning in the carb, that must line up with the openning in the mounting block for this to happen. Zenoah offers a carb rotation kit and I have seen many guys install it incorrectly with the openning blocked and their engines do the same thing until the opennings are aligned. The carb simply doesn;t pump fuel.
Yep, not only have I seen it I have done it a number of times. If the gasket is installed so that the pulse hole is blocked it won't draw gas. Been there too!!! Make sure your gas tank is vented. The chain saw used a vented cap!! That's just an FYI, not your draw problem at the moment but if you don't vent the tank it will be a problem!! Yes, I have forgot to unplug my vent line too!!! So, double check the carb block and gasket!!! I'm betting the pulse hole is plugged.
Old 03-22-2010, 05:43 PM
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Neb_16
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Default RE: 28cc Gas engine not getting fuel? Help please? i have not clue

I tried your suggestions and found that the reed valves weren't seating correctly... I guess that caused the crankcase pressure to leak and not pump the fuel through the little hole. I swapped out the reed valve and she fired right up. Thanks for the help guys!!!

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