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Mower not starting - carb trouble?

16 years ago

I have a Poulan Pro W4QN20RC mower with a 4 HP Quattro, Briggs & Stratton engine (model 10A902, type 2139). I am not sure of its age but it has run very well for the past 2 years.

A month ago, it refused to start and I decided to changed the oil, the spark plug and the air filter. I also installed a new primer, a diaphragm for the carb and cleaned out the carb using B&S carb/choke cleaner. I also made sure that I was seeing a good spark.

It worked fine after that but last week it would not start until it was primed at least 15 times. I have never had to prime it more than 5 times before! This weekend it would not start at all. I poured some starter fluid into the throat of the carb and the mower starts immediately but then dies after a few seconds. I have made sure that this season, I use fresh gas every time I mow.

Could there be any other problems with the carb? I have heard that there could be problems with air gaps or some such thing but I don't know how to get rid of it.

Has anyone faced such an issue? Can someone please help out?

Thanks,

Andy

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Comments (2)

bill_kapaun
16 years ago
Just follow the thread on B&S 4.5 won't start. Same engine, same problem.
Probably the same solution?
bill_kapaun
16 years ago
Hookem- I moved my answer back here so ridger dodger won't keep receiving emails.
Look inside that "boss" for a hole. I think the "jet" is cast in to the cover?

Now I don't have one of those carbs, so I AM going on hearsay, although I consider the source to be quite reliable.

Also recheck the screw tension that holds the carb to the tank.
The fact you had to prime it 15 times makes me wonder if there might be "crud" in the tank that got lodged (again?) in the little "U" shaped flapper on the diaphragm. That little flapper IS your fuel pump.
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per deeredoctor, I will be changing to a brass needle in the float valve. However I have never seen any resistance with the factory plastic valve or seating issues,I will however try the tap on the bowl while engine is cranking when this troublesome issue rears its ugly head again. Also, I have completely checked the fuel line from tank to fuel pump and pump to carb. There is plenty of vacuum at the pump and when the engine fails to fire, plenty of gas is pumping through the fuel pump. As a side note, I have also completely drained the fuel tank at beginning of season to rule out any foreign matter in gas, i.e. water. Will keep you posted.
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