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I have a nitro 340 rupp that wont keep running unless i spray gas into the carb. I have cleaned the carb. plenty of gas but wont stay running already checked the gas lines and check valve.
 

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I have a nitro 340 rupp that wont keep running unless i spray gas into the carb. I have cleaned the carb. plenty of gas but wont stay running already checked the gas lines and check valve.[/b]

What kind of fuel pump do you have on it? And, what brand carb? I'm not familiar with Rupp in general, but it sounds like your fuel delivery is lacking.
 

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What kind of fuel pump do you have on it? And, what brand carb? I'm not familiar with Rupp in general, but it sounds like your fuel delivery is lacking.[/b]
It has a tillotson hr carb with the fuel pump in the carb, when i try to start it there is always gas going back through the return line lots of gas coming into the carb, cleaned out the gas tank and put in fresh, took off the carb soaked it and blew it out, about a week ago and sprayed gas in it and it ran i put on like 20 miles and shut it off whent out the next day and it woulnt start.
 

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It has a tillotson hr carb with the fuel pump in the carb, when i try to start it there is always gas going back through the return line lots of gas coming into the carb, cleaned out the gas tank and put in fresh, took off the carb soaked it and blew it out, about a week ago and sprayed gas in it and it ran i put on like 20 miles and shut it off whent out the next day and it woulnt start.[/b]

water in the fuel maybe froze up in your carb.
 

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Pardon me if this is a dumb question, but you took the carb apart to soak it, right? Soaking it while assembled won't clean anything but the outside.

If there is fuel in the return line the pump must be working. Have you checked that the inlet needle is not stuck shut, and that the inlet needle lever is set at the correct level?

Here is a link to a page on my web site where I have carburetor manuals available for download.
http://bayshorecad.com/Sleds/CarbManuals.html
 

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Pardon me if this is a dumb question, but you took the carb apart to soak it, right? Soaking it while assembled won't clean anything but the outside.

If there is fuel in the return line the pump must be working. Have you checked that the inlet needle is not stuck shut, and that the inlet needle lever is set at the correct level?

Here is a link to a page on my web site where I have carburetor manuals available for download.
http://bayshorecad.com/Sleds/CarbManuals.html[/b]
yes i did take the carb apart to clean it the only thing that i didnt take apart was the welch plugs because i thought that i had to replace them if you took them out. The inlet needle was freely moving and i adjusted the lever o that it was flush i didnt soak the diaphram because i read that you wernt sopose to i dont know if this is wrong And how does the inlet needel work how does it pump the diaphram
 

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The space on the "wet" side of the diaphragm is the "float bowl"..As the fuel is drawn out of this area, the diaphragm moves up opening the needle and allowing more fuel in..These carbs are VERY temperamental. The final solution is a Mikuni with an external pump feeding it..
 

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Mikuni is the way to go.You should be able to find a used one for a song.If you plan on keeping the tilly get a rebuild kit and start there.I had several Rupps with daiphram carbs and it seemed like i was cleening and rebuilding the carbs more than riding. Check the daiphrams for the smallest imperfection, pin holes and other damage. Also even with a good fuel filter it seems the smallest of gunk can mess those Tillys up. Good luck.
 

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Mikuni is the way to go.You should be able to find a used one for a song.If you plan on keeping the tilly get a rebuild kit and start there.I had several Rupps with daiphram carbs and it seemed like i was cleening and rebuilding the carbs more than riding. Check the daiphrams for the smallest imperfection, pin holes and other damage. Also even with a good fuel filter it seems the smallest of gunk can mess those Tillys up. Good luck.[/b]
will the mikuni fit right on to my rupp or do you have to get something to make it fit
 

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will the mikuni fit right on to my rupp or do you have to get something to make it fit[/b]
You'll need a fuel pump and a place to mount it. You'll need new throttle and choke cables with ends that will fit the Mikuni and your current levers. You'll need an adapter to fit the spigot-mount Mikuni to the bolt-on intake manifold. If the engine sits at an angle, you'll need an adapter so that the Mikuni sits relatively level so the float bowl works properly.
 

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will the mikuni fit right on to my rupp or do you have to get something to make it fit
[/quote
You need everything joslberg said. The parts should be easy enough to find. I think I have a mik34
laying around if your interested. If I remember correctly it was off a 78 pantera 500cc. Maybe more carb than you need but should work fine.
 
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