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Briggs 286H77 Type 0165 will only idle!!


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10-08-08, 09:13 AM   #1  
Briggs 286H77 Type 0165 will only idle!!

I've been working on Briggs engines for over 30 years. NEVER had I had one that has stumped me like this one!! Customer brought this in with a complaint of the unit will idle only--will NOT accelerate. Said it all started one morning without any warnings.

Rebuilt the carb, linkages and throttle cable all fine. Simply will not accelerate from idle! This is on a Toro zero turn.

Any suggestions warmly welcomed!!!






GI2

 
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30yearTech's Avatar
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10-08-08, 10:35 AM   #2  
What happens when you try to accelerate the engine?

 
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10-08-08, 11:22 AM   #3  
Briggs 286H77

Hi there...

It starts right up and idles...moving the throttle cable to FAST does nothing. Governor links, springs, and butterfly open but it will not increase speed. Idles beautifully!


If it was a 2 cycle, I'd swear it acts as if the exhaust was restricted. Had that in an Echo power blower once...GI2

 
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10-08-08, 03:19 PM   #4  
Posted By: briggsowner Hi there...

It starts right up and idles...moving the throttle cable to FAST does nothing. Governor links, springs, and butterfly open but it will not increase speed. Idles beautifully!
Are you saying that the throttle plate in the carburetor opens, but the engine just continues to idle???

I just want to be clear and understand what you are describing.

Could you possibly post a picture of this carburetor installed on the engine?

 
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10-08-08, 03:40 PM   #5  
Briggs 286H77

The throttle opens just fine. It's the Nikki float type carb.

I've looked at this from multiple angles---next step is to pull the muffler and see if it's restricted. Had this on an Echo blower once and that prevented it from accelerating. Of couse, that's a two cycle. Starts right up and will chug all day at an idle.

 
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10-08-08, 03:59 PM   #6  
If the carburetor throttle plate is opening and the engine continues to idle ( it should die if the problem is in the carburetor not feeding enough fuel), then I would pull the valve cover and take a look at the valves. Check the lash and make sure both valves are operating and opening fully. I have had a similar issue with an engine that had a worn down lobe on the cam shaft and the exhaust valve was barely opening, the engine would not build any rpm's, although it did not idle very well.

 
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10-09-08, 12:14 AM   #7  
I agree on the camshaft lobe suggestion. I've had the same problem.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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10-09-08, 06:28 PM   #8  
Briggs 286H77

Folks:

Thanks so much for the suggestions! I pulled the valve cover and lo and behold, the intake valve barely actuates. Pulled the head; valves and seat function normally. I placed the push rod against the intake lifter and compared the movement to the exhaust side. Intake barely moves; exhaust functions fine.

Suspect that the infamous plastic cam gave way. Will order a new cam and gasket set tomorrow.

Thanks again, gang!


Tom

 
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