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Need Some Carb Help...i Think


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#1 fedora OFFLINE  

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Posted September 11, 2013 - 04:45 PM

Hello all,

 

I have an 91' B&S 18 hp twin cylinder engine(model 422707). Since I've had it, I've had to run it at half choke. The coil went out, so while I had all the tin off replacing it, I found 2 bolts on the right head backed out against the cover, so I also replaced both head gaskets and de-carbed the piston tops and heads.

 

I pulled the plug off the carb bowl and pulled the low speed jet, and sprayed carb cleaner in everything, now I need to run it at almost full choke, and I have almost no torque. I'm guessing I moved some dirt around inside, but I could be wrong. While I wait for a response, I'll take the carb off and give it a proper cleaning to see if that clears it up. 

 

Any thoughts?

 

 


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#2 MH81 ONLINE  

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Posted September 11, 2013 - 04:46 PM

Sounds like you are either not getting fuel thru the carb or have a substantial air leak.  I would check for an air leak before removing the carb.



#3 chris m OFFLINE  

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Posted September 11, 2013 - 04:58 PM

I just went through this on an Onan twin. I took the carb off, and dismantled it. It looked fairly clean so I opted to just spray all the ports out. I put it back on and it was worse than when I took it off lol.

 

I went against my own carb cleaning principals( because I was rushing) and It came back to bite me. So... I took the carb off (again), took it all apart and then soaked it overnight in my can of carb cleaner. The next day I took it out of the soak, then sprayed everything again with cleaner. Reassembled it and installed, She started right up and runs great now.

 

Moral of the story, Do it right the first time. :wallbanging:

 

Also like Alan said, check for an air leak first, possibly the mounting flange on the carb is warped or the gasket needs replacing? Or maybe the throttle or choke shaft is worn out?

Also make sure you don't have a blockage in the gas tank.

 

Good luck :thumbs:


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#4 HDWildBill ONLINE  

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Posted September 11, 2013 - 05:16 PM

I think Alan and Chris pretty much covered it.  One other thing is check to see what kind of out put the fuel pump is putting out.


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#5 fedora OFFLINE  

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Posted September 11, 2013 - 08:00 PM

Thank you all,

 

I checked everything out as far as fuel lines, air intake, ect. I ended up doing a partial rebuild on the carb, I've never rebuilt one of those square units before. I pulled the low/high speed jets, the top/float, and the front fuel diaphragm. I can honestly say I've seen cleaner coal mines, lol. After going through every nook, cranny, and passage, it runs like a champ.

 

I haven't had the hood off before to see the front of the engine, I'm surprised any of the linkages worked with all of the crud built up on it. After three afternoons of putting around on it, it has a new coil, head gaskets, spark plugs, fuel filter, air filter, belts, sharpened blades, and the brakes now work. This site is a huge help, and a great group of people.


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#6 HDWildBill ONLINE  

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Posted September 11, 2013 - 08:10 PM

Thanks for the feed back.  Glad you got it up and running.  






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