Engine Surging

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  #1  
Old 03-14-03, 11:23 AM
J A Boggan
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Question Briggs hunting and surging

I have a Briggs...model # - 42A707, type # - 1653-01, code # - 9506285A. It hunts and surges at idle and wot, however it will smooth out if I put about 3/4 choke on it. I have checked the static governor adjustment also the compression on both cylinders is identical (120 psi). It has the older "three bolt" fuel pump cover with a single idle mixture adjustment. I have ordered a carburetor / fuel pump kit, just thought someone might have another idea. Thanks in advance.
 
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Old 03-14-03, 03:43 PM
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You have the right idea...Pull the top off of the carb, remove the 5/8" plug on the left hand side of the carb at the bottom, use an allen wrench inserted through the drain hole to get the jet out. Clean out the jet and the area behind it where it is screwed in, clean out the bowl, and you should be good to go.
 
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Old 03-14-03, 05:26 PM
J A Boggan
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I appreciate the information Cheese.
 
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Old 03-17-03, 06:08 PM
J A Boggan
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Thumbs up

That corrected the problem.
 
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Old 03-17-03, 06:43 PM
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Good job! Glad to help!
 
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Old 03-20-03, 07:10 AM
J A Boggan
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Question

Cheese,
Could a faulty fuel pump cause a hunting and surgeing problem? Also, could valves being out of adjustment, sticking or ect. cause this problem? Just trying to determine all causes.
Thanks in advance.
 
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Old 03-20-03, 10:20 PM
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Engines do funny things sometimes, so I suppose it is possible that any of these things to cause this problem. 90% of the time, surging is caused by a lean air-fuel mixture. The other 10% is probably too rich of a mixture, usually due to a clogged air filter. A bad fuel pump can cause surging if it happens to be supplying the carb with just enough fuel to keep it running, but not quite enough to keep the bowl completely full. I have never run into that scenario, but it is possible.

Generally, valves out of adjustment will not cause surging. Usually the engine will be hard to turn, having trouble getting past the compression stroke, if the valves are too loose. If they are too tight, you may get some popping, fuel blowing out carb, loud exhaust, low power, fast cranking speed, long cranking time. Then when the engine finally cranks up, it gradually builds up to speed much slower than normal.

Sticking valves cause backfiring, skips, fuel blowing out the carb, or no start at all if the valve is completely stuck.
 
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Old 03-21-03, 04:59 AM
J A Boggan
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Thanks for your reply Cheese.
 
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Old 03-22-03, 01:11 AM
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Anytime!
 
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