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Craftsman 18hp RLM (carb problems)


GW1's Avatar
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09-23-03, 05:23 PM   #1  
GW1
Craftsman 18hp RLM (carb problems)

Resurecting an 18hp Craftsman RLM with a B/S model#422707 type# 1511. It's been sitting up a couple of years outside at a friends house. Originally cranked up off of a temporary fuel tank (a little rough but decent) pulled carb and the bowl was full of corrossion and water, thoroughly cleaned with carb cleaner, blew out with compressed air, and replaced the bowl gasket. noticed the mixture jet was screwed in all the way. Fuel pump appeared OK. Runs worse now, really rich. Will only run with the choke almost closed. Plugs are black and wet. B/S website list the mixture jet as non adjustable?? Also the throttle shaft has no slop in it. Can,t find it sucking air anywhere. What else could it be? I would appreciate any comments of help. Thanks

 
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09-24-03, 12:43 AM   #2  
Hello GW1!

If it only runs with the choke closed, it is running lean. A common problem on these carbs is main jet blockage. The main jet is at the lowest point in the bowl, and is prone to collect trash. Remove the 5/8" drain plug on the side of the carb to gain access to the main jet. Look into the hole and you will see the jet. It comes out with an allen wrench (forget what size) 1/4" I think, maybe 3/16". Remove the jet and clean it out, and then use a pick or piece of wire to clean out the area behind the jet, in the hole it came out of. This should help your problem. Let us know!


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09-24-03, 10:43 AM   #3  
GW1
Still won't run

I already cleaned the main jet but just to be sure I bought a complete kit and checked everything again. All passages are clear along with a new fuel pump/ needle/ gaskets/ and springs. Still won't run without the choke closed at an idle but at high RPM's the choke can be opened almost half way. Do I have tunnel vision on this one?? Could it be ignition?? Both plugs are firing, although I haven't changed them. Electronic ignition?? Or just a bad carb?? I'm stumpped!!
Thanks GW1

 
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09-24-03, 11:35 PM   #4  
You still have a carb blockage. Did you pull the main jet OUT and clean behind it?


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09-25-03, 08:31 AM   #5  
GW1
Yes, I pulled the main jet out and cleaned behind it. I have now completely disassembled and soaked in Berryman's Chem dip overnight. Still acting the same. Is this a common problem? A new carb lists for $130. I am considering bitting the bullet and buying a new one, but I'm one of them guys that can fix anything and it just eats me up when I come across something like this that I can't solve. How often do you come across a carb that just won't run right no matter what you do? GW1

 
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09-25-03, 09:36 PM   #6  
Once in a while I do, but the kind you have should not be such a problem....they are not troublesome carbs usually. I wouldn't buy a new one yet. Have you tried backing out the mixture screw a bit? (two full turns out from lightly seated is good). If that doesn't help, check your float level, if you haven't already, and also verify that the fuel pump is pumping plenty of fuel. To see the volume of fuel being pumped by the pump, you have to remove the top of the carb and spin the engine. It will shoot gas out of a passage in the carb upwards, (if working right) so be careful. Have you used compressed air to blow out the carb passages?


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10-03-03, 02:58 PM   #7  
Did you figure this out?

 
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