Export thread

Bought a Murray with a 4.5Q Briggs and Stratton motor on it. Non propelled. I am at work at the moment and can supply all model / SN when I get home.

The Problem:
Previous owner mentioned the lawn mower had been turned over, upside-down. Mower will start, however bogs down, chugs, rough idle, smokes little to none... occasionally shutting off completely. Spark plug quickly becomes dry fouled with good bit of dark black carbon build up.

What I've Done:
Drained oil
Drained gas
Cleaned air filter
Carb cleaner on carb, gas tank, spark plug port
New oil
New gas
New spark plug

Unfortunately for me at about midnight last night.. cranked it up and got very similar results. At first the primer didn't even want to prime, then it started eventually. Spark plug quickly got the dark black build up... and mower just still idled very rough. I have pictures, and video and like I said will have SN's when I get home. Next I was thinking of replacing diaphragm... but after that it is kind of beyond my scope of what's next. Hoping to learn some new tricks here. Thanks in advance for anyone who takes the time to help me..... I am sure I am breaking some rules, and especially by not having the exact numbers, but hoping to have something to do tonight to get it running maybe, and if I need to buy some parts.... before it gets too late.

I would bet that the diaphragm is the main culprit. Under where the intake pipe connect the carb will warp, and the diaphragm will get sucked in, and then suck fuel around the diaphragm, and run rich. I didn't look at the list of already down very well, so I will add make sure the air filter isn't clogged with oil.

ILENGINE said:

I would bet that the diaphragm is the main culprit. Under where the intake pipe connect the carb will warp, and the diaphragm will get sucked in, and then suck fuel around the diaphragm, and run rich. I didn't look at the list of already down very well, so I will add make sure the air filter isn't clogged with oil.

Click to expand...

Thank you very much... I am hoping that will be it, I will locate a new one and replace it. Thanks again for chiming in.... any other ideas are greatly appreciated.

ILENGINE said:

I would bet that the diaphragm is the main culprit. Under where the intake pipe connect the carb will warp, and the diaphragm will get sucked in, and then suck fuel around the diaphragm, and run rich. I didn't look at the list of already down very well, so I will add make sure the air filter isn't clogged with oil.

Click to expand...

Hey, just an update. I stopped and picked up a new diaphragm and gasket. Put everything back together and it started on 2nd pull. Ran like brand new for 30-40minutes while I cut the whole front yard. I shut it off, came back about ten minutes later... won't start at all... not even a sputter. Confirmed it had spark, checked oil, added fuel. Not even a bump.
Pulled carb again, everything looked normal.. let it sit for awhile. Nothing. So I am at a loss now... I guess only other step is pull carb apart further? But it didn't miss a beat when it was running.
Any advice greatly appreciated... My next step is craigslist this one as repair needed and cut my losses.

Turbodr said:

Hey, just an update. I stopped and picked up a new diaphragm and gasket. Put everything back together and it started on 2nd pull. Ran like brand new for 30-40minutes while I cut the whole front yard. I shut it off, came back about ten minutes later... won't start at all... not even a sputter. Confirmed it had spark, checked oil, added fuel. Not even a bump.
Pulled carb again, everything looked normal.. let it sit for awhile. Nothing. So I am at a loss now... I guess only other step is pull carb apart further? But it didn't miss a beat when it was running.
Any advice greatly appreciated... My next step is craigslist this one as repair needed and cut my losses.

Click to expand...

Also it is worth mentioning, while it was running... zero smoke or sputter.. and then spark plug stayed mint, no build up. Oil level remained constant and clean.