B&S 8hp Wood Chipper

ga_newbie

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I have an old Bolens wood chipper with an 8hp Briggs & Stratton engine (model 190412). It runs well for a few minutes then the engine starts to struggle. It seems like the RPMs drop. Once they drop so low it sounds as if the engine is going to stop, the engine picks back up and runs at normal speed for a minute or less. This usually continues for 5 - 10 cycles, up and down, then the engine finally does shut off.
Six months or so past, I pulled it out from our shelter after several years in storage and installed a basic tune-up kit, changed the oil. It ran, but with this RPM issue occasionally, which seems to be getting worse.
I took apart the carburetor and did not see any obvious problems. The components looked clean and unobstructed. The only defect I noticed was a corroded outer rubber casing of the fuel line to the carburetor.
When the engine is running, I notice the idle speed adjustment turns freely. I don't know if that's normal. This is my first adventure into small engine repair, so I don't know what to look for let alone what to adjust or replace. Any guidance would be most appreciated.
 

Scrubcadet10

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most likely an issue in the fuel system, be sure you have good fuel flowing from the tank with no obstructions in the gas line.
wouldn't hurt to clean out the carburetor too with parts cleaner,
this video should help you, i believe it is the correct set up,
 

bertsmobile1

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If the fuel line is old replace it.
Old fuel line was compounded for petrol. a liquid that has not existed for decades.
Modern fuels which are basically light fuel oil dilluted with scrap organic solvents will attack the fuel line .
While you ae there, remove the fuel tap and tank .
Clean out both of them.
A lot of fuel tanks have the tap sitting in a dished section and this can fill with dirt, rust & other debris blocking off the fuel outlet.

If the fuel line is good, when you remove the fuel cap and pull the fuel line off the cvarb you should get a strong continious flow of fuel the full size of the hose.
 

ga_newbie

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Thanks for the advice. The good news is that I didn't make the problem worse... bad news is the problem is still there.
I replaced the fuel line, cleaned the gas tank and replaced the fuel filter. I cleaned the carb with carb cleaner.
Problem is exactly the same as before. It ran well for about 2 minutes, then started dying and resuscitating until it finally quit.
Suggestions for what I might try next?
 

Scrubcadet10

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I would buy an inline spark tester, fit it and see if the spark is cutting out when it sputters.
 
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