Wessex Flail Mower cutting out

[roys]

Has it got a fuel stop solenoid on the bottom of the carb ?

 

No nothing fancy like that on it.

[roys]

Dam you Briggs and Stratton, wasted so many hours on the engine this weekend,no stripped down the carb again, cleaned all the jets, changed fuel filter, cleaned out tank, still same fault.

So cleaned carb again, did away with pump, filter, tank, by rigging up a temporary tank gravity feeding into carb, same fault.

Next step, change the two spark plugs. It just sounds like fuel related but surely I have eliminated that now. So plug change it is.

Dam dam dam

 

So another day on the dam Briggs and Stratton, B&S won again, new plugs in it same again cut out after 25 minutes or so, quickly took of the top of the carb to check float chamber, it was full.

Tried to start it would only go if I tickled the choke would not rev up, checked jets all ok. This time when assembled I blasted easy start into it and it revved up, so it must be petrol, mustn't it? Can't be spark!!

Tomorrow I will take carb fully off engine to see if there is a sneaky filter internal or something else I am missing.

The saga continues.

[njm]

So another day on the dam Briggs and Stratton, B&S won again, new plugs in it same again cut out after 25 minutes or so, quickly took of the top of the carb to check float chamber, it was full.

Tried to start it would only go if I tickled the choke would not rev up, checked jets all ok. This time when assembled I blasted easy start into it and it revved up, so it must be petrol, mustn't it? Can't be spark!!

Tomorrow I will take carb fully off engine to see if there is a sneaky filter internal or something else I am missing.

The saga continues.

 

Sticking float or leaking needle valve would be a best guess without seeing the machine , had a couple of brass floats with pin holes in them before , only other odd fault like this i have had before was an exhaust valve jamming open a few tho when machine was hot . Tank spotless ect ?

[roys]

Sticking float or leaking needle valve would be a best guess without seeing the machine , had a couple of brass floats with pin holes in them before , only other odd fault like this i have had before was an exhaust valve jamming open a few tho when machine was hot . Tank spotless ect ?

 

Tell me more about sticking float or leaking needle valve please, I thought by quickly taking the top of the carb and seeing the float chamber full would prove the needle valve, also there is nowt coming out the wee overflow pipe. What else should I check there please?

[geoff]

I don't know what spark setup it has, but I still think something electrical is breaking down.

[roys]

Hi Geoff, I could be wrong, but I kind of ruled that out because it roared away at full revs with easy start getting sprayed into carb, more than willing to be proved wrong though.

[njm]

Tell me more about sticking float or leaking needle valve please, I thought by quickly taking the top of the carb and seeing the float chamber full would prove the needle valve, also there is nowt coming out the wee overflow pipe. What else should I check there please?

 

Yes full of fuel but at the correct level ??

Check the float is not full of fuel or fouling the float chamber and sticking , also check the float height is correct ! needle valves can leak ie not seal correctly flooding the chamber , couple of mm extra fuel in the chamber can cause the engine to flood when at working rpm due to the raised level of fuel in the emulsion tube , Brass or plastic float ? ethanol can destroy both types .

Spark breaking down ? a flooding engine will short out the ht system , a hot engine will also cause a weak ht system to fail but you say it fires on easy start

Picture of the carb ? Debris floating around the fuel system ? how clean is the carb , my idea of clean is a full strip down and ultrasonic bath

Edited July 8, 2016 by njm
info

[miker]

Take fuel pipe off at carb and blow back into tank with cap off, also check that fuel line isnt getting hot and evaporating fuel before it gets to carb

[roys]

Plastic floats, will get a couple of pics tomorrow, not going to workshop now got a couple of drams in me now

[roys]

Hi miker, vapour lock was actually the first thing I thought about that as the fuel lines are right over the top of the hot valve covers, but I ruled it out after I replaced the fuel filter for a clear one and could see the fuel getting to the carb, also as stated the float chamber was full. I have also replaced all the fuel lines as they were a bit cracked due to the heat. Think from a time gone by British Leyland had that problem on some cars.

 

Interesting about the float chamber being too full njm, will need to look into that a bit more.