O/T: Small Engine tech help needed

I have a Briggs & Stratton Quantum 5.5 that won't run. I can prime it and it will burn the gas in the carb at low RPM but won't continue to run after that. I replaced the plug and so forth already, the usual tune up stuff, no change. Sound familiar to any of you?

 

Sounds all too familar!! I think you have to clean and rebuild the carb. water in the gas is the cause of many problems,and the quality of the camel-piss gas isn't getting any better. It cruds up the system. Try using some racing gas,just for kicks,the real leaded type!!! Smells great!, tastes awlful!! good luck, Glenn

 

did you clean the area on the inside of the flywheel ,sometimes it gets surface rust and the magneto won't fire worth beans...

 

1. Check the gas in the tank...old gas ain't good, and LOW OCTANE fuel is actually BETTER...it burns faster and the compression ratio in those engines is way low...cheap no-lead always worked best for me!

2. Spark plug condition and gap. A fouled plug or too big a gap won't run worth squat. (You gotta keep your **** in perfect tune when ya only got ONE cylinder...no others to pick up the slack!!).

3. Points. I replace 'em every year. New engines use an electronic module that will directly replace the points and condensor in older models in most cases if you wanna upgrade it. The points gotta be in pristine shape and gapped correctly to run right. The thickness of an average business card will get your point gap in the ball park if you're a low tech dude!

4. Flywheel key. If your flywheel key is sheared or even damaged enough to move a bit, you won't be goin' anywhere! They are cheap and DESIGNED to give if the engine stops suddenly...just make sure you torque your flywheel back down BEFORE you turn the engine over...the key will shear if the flywheel ain't tight!

5. What kinda carb ya got? If it's a suction feed (mounted directly on top of the tank), those are pretty simple. Make sure the pickup tube that goes into the tank fits snuggly into the carb and is not obstructed with varnish, debris, or dead bugs.

Take apart the carb and clean it thoroughly...these engines often get stored for long periods and old gasoline deposits inside the carbs can gum 'em up and plug p***ages. Remove your adjustment needle screws and blow the p***ages out with carb cleaner and air. Re***emble your carb and give it a try.

If you have the "diaphram type" of carb, mounted away from the tank...the diaphram often splits or leaks on these. Pulses from the intake cycle on the engine operate the diaphram which pushes fuel through the carb. Bad diaphram means engine won't run!

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Just a few quick tips starting with the easiest first to help ya out...give a yell if ya need more specific help or need to go further into the engine.

 

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If you have the "diaphram type" of carb, mounted away from the tank...the diaphram often splits or leaks on these. Pulses from the intake cycle on the engine operate the diaphram which pushes fuel through the carb. Bad diaphram means engine won't run!

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This would be my guess since it will run when you squirt gas into it. If the diapghram gets a hole it won't pull the gas.

 

Thanks Hack, I'll be tearing into that one tomorrow.

 

i was guessing the diaphram, but hack already covered that.

 

If the last batch of fuel left in it over a season or so was the reformulated ****, it will deteriorate into little grtty things in the bowl as opposed to varnish. The stuff does not sisolve quickly in carb cleaner or at all in gasoline! The little ******s will plug orfices and crud up everything. the stuff also seems to attract water pretty well. Of course that makes for more **** in the carb and the tank! Due to this swill no small engine on the mighty Cornfield Estate is without an in line fuel filter.
Sooooo.... Clean the carb, removing all corrosion from the bowl. Put a coupe ounces of iso-propyl alcahol in your fuel supply to help the potential water problem. If the tank is at or above carb level, you probably have a shut off valve. Use it when the engine is not in use to prevent the bowl from filling with water right after you start 'er up.( You will forget the alcahol most of the time!)