B&S 28N707 running problem


Old 05-15-05, 09:54 AM
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B&S 28N707 running problem

Hi everyone! Glad I found this forum; looks like this just might be the most useful one on the internet! Have already learned a lot just by searching and reading.
Except for this particular problem!
I recently bought a used Craftsman LT4000 917.252510 mower, with the B&S 28N707 15hp engine. This is my first riding mower, so I'm trying to learn all I can about it, have ordered an owner's manual to assist me with some of my questions.
However, I don't think it'll cover this one! When I first start it, it seems to take a really long time to warm up and run in the normal speed range, such as moving the throttle to the position marked for mowing. The engine will rapidly slow down and speed up again, with a pop at the slow end of the cycle. After 4 to 5 minutes, it will smooth out and run fine, till then I have to keep it running at the fastest throttle setting.
Have replaced the air filter,spark plug, fuel filter, and changed the oil, as well as a general cleaning. The issue with the running is the same after the new parts as before.
Also, noticed that when the engine is running in that mode of fast to slow and back, there is a lever/spring assembly connected to the carb that is moving back and forth with the engine speed changes. Don't know enough yet to tell if that is a clue to what is going on.
Thanks in advance for any ideas/suggestions as to what to do about the engine.
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Old 05-15-05, 10:20 AM
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Removed The Nut To The Carb Bowl... Clean This Out With Some 2+2 And Also Spray Some Up Into The Middle Of Carb Where That Nut Came Out Using The Hose That Coms With The Spray And Put Back Together And Try....
Old 05-15-05, 01:42 PM
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No nut

I just looked, there isn't a nut at the bottom of the carb bowl, there is an electrical device of some sort there. Does this thing have an electric fuel cutoff or choke in addition to the manual choke? Maybe this device may have some bearing on the problem I'm having?
Thanks bambiblaster, I was wondering if maybe the carb needs cleaning any way, that might well be the fix.
Old 05-15-05, 11:07 PM
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That is the anti-backfire solenoid. It also funtions as the bolt that holds the carb bowl on. You'll need to remove the bowl and clean it out as suggested.
Old 05-16-05, 09:33 AM
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I'll remove and clean that bowl this evening,in all likelihood, it probably does have a little trash in it.
Anti-backfire solenoid-- I would have never figured that out! I'm liking this forum more and more; thanks guys, I'll let ya' know how it runs after the cleaning!

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