Small Engines (Lawn Mowers, etc.): 5 hp B&S wont start, briggs and stratton, nosed pliers

Question
Greetings Sir,

I have a problem that hopefully you might be able to help me with.  My father has a Murray push lawn mower with a Briggs and Stratton 5 hp model 12f702 code 0714 that will not start.  It was working fine one or two years ago when the pull cord broke.  He has three mowers, so he just set it aside, used the others, and forgot about it.  I installed a new pull cord and gas line and then added some gas.  I pressed the primer bulb three times and pulled the cord.  The mower sputtered to life and ran for about two seconds before it died.  I pulled the cord again and it ran for about a second.  I looked at the front of the mower and a small stream of gas was coming out from around the primer bulb.  I figured it needed a new primer bulb.

I went online to see about ordering one when I stumbled across this website and where someone asked about a leaking primer bulb and they were told to check the needle and float first.  I pulled off the carb and with some difficulty opened it.  The bolt and bowel acted like they were rusted in place.  Inside I found a thick white deposit coating the entire insides.  The float/needle would not budge.  I used a punch to knock out the pin partly and wiggled/pulled it out with needle nosed pliers.  I then used the pliers to pull out the needle.  Carb cleaner did nothing.

Since it looked like a lime deposit to me, I used phosphoric acid (The Works bath room cleaner---a knock-off of CLR) to clean it.  Squit in, wait 30 seconds, rise.  After about 5 times it came out nice and clean.  I used a paper clip to probe all holes.  I sprayed it with carb cleaner to displace any water, reassembled, and everything seemed to work fine.

I put the carb back on, but the mower will not start now.  The spark plug is sparking.  When taking the carb off, a small peice of the seal that goes between the carb and the primer bulb peice broke off around the outer edge.  Any suggestions you might have would be greatly appreciated.

Thank you for your time,
Johnathon

Answer
Hi Johnathon,

You have put in a great effort and done the right things so far.  The carb is probably in bad shape and may need replacement at this point.  If the mower can be started and kept running by adding fuel or starting fluid to the carb's intake, then a lack of fuel to the engine is certainly the problem.   You could try cleaning it again making sure that all the openings are clean.  A finer wire may be needed for probing.  Check the primer bulb for any tears or cracks but a clogged opening may be causing back pressure and leaking when priming.  Also check for a good fuel flow from the fuel line at the carb's inlet fitting.

Let me know how you make out.
Michael