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a little help needed if you can some pics and vid it might help



a little back ground i rescued this from the tip some one was going to chuck it said its been left out side for a year
after a quick look the cable to the spark plug had been cut i had a spare so put it on and did a spark test and that was fine
then went to the carb and fuel tank took them apart cleaned the fuel tank and used carb cleaner on the carb and all holes
filled with new fuel and primed and started first pull

sorry forgot to add that i drained the oil and filled with new

now to the problem it runs fine for 10 to 15 seconded untill the prime fuel i think runs out and then starts searching revs up and down and does not stop

any ideas

thanks for any help

i have tryed to add a vid hope this helps a lot to explain what the problem is

You need to replace the diaphragm and gasket between the carb and tank.

Rivets said:

You need to replace the diaphragm and gasket between the carb and tank.

Click to expand...

how definate are you the new gadget and diaphragm will fix it

THANKS FOR THE HELP

any idea of the part number ?

from a quick look P/N 795083 thanks angel

From your description very confident. 795083 is correct. Make sure you install them properly, diaphragm agaianst the tank, gasket against the carb.

Thanks for the help rivets

That was going to be my next question

In my rush I bought a 3rd party copy part instead of a Briggs part
What do you think on copy parts I assume there ok but generaly don't last as long

Thanks again for the help

The bits of rubber of the diaphragm did seam to be a bit hard and not flexible

I always try to use OEM parts. I know what I am getting and if I get a bad part I can return it, even if it is used. You must remember that I am a certified technician for many engine manufacturers and it is in my best interest to use their parts. Plus, my reputation is toast if I use non-OEM parts and the unit comes back.

my fault should have read the description better but hayho they have been posted so will just have to try them
the cost was about half the price of a oem set so will have to hope they do the job looking at the comments they do ok

again thanks for the input will post on the fourms i hope in a day or so depending on time scale of the postal service

sorry no such luck with the card diaphragm and gasket but once it was installed i sprayed carb cleaner around the oring seal on the back of the carb that connects to the engine and the reving stoped and run fine for a few secs any idea on the oring part number ?

thanks angel

The low speed circuit in the carburetor is plugged. Give that carburetor a real good cleaning. Maybe if you know a someone with repair shop they will let you use their carburetor cleaner.

just to report back the diaphragm and gasget did no good and still runs as well as before after runing for a while it did seam to get a little better




reynoldston can you expand on what you have said i have tryed new bits and the rubber that attaches to the carb to the cylinder i have ptfe taped to see it there was a leak there but that's not the problem as well

can i clean the holes with wire ? or can i not clean the low speed circuit in the carburetor with out a tank and such ?

thanks for all the input

I can tell you the way I do it. I disassemble the carburetor and soak it over night in strong carburetor cleaner which comes in a gallon can . Then I take a aerosol can of carburetor cleaner and try to clean out all the ports and small holes. Then I take some small tag wire and do some more cleaning. Then some compressed air and give every thing a good blowing. Any welch, soft plugs or needle valves I remove them and clean under them. Also then I take a carburetor apart or put it back together I do it over a large rag so if any small parts fall out I can find them easy. Just the way I do it, if right or wrong it works for me. 100% hell no, I some times have to do it over several times to get them right or end up replacing the carb.

You really cant go wrong with this engine.
Usually its the diaphragm and good clean.
If that does not fix it then it could be the o-ring or a crack in the manifold that opens up due to heat when engine running which is sucking air instead of fuel.

You seem to have diagnosed it with spraying carb cleaner at manifold.

Also the 2 gov springs can also cause the problem.
The long spring of the 2 requires you to set the RPM to 2900 and the small spring then sets the last 100RPM to 3000RPM but you need a tachometer for that.

Yep as above.
not much can go wrong with these carbs.
It is not a good idea to spary around the manifold of a runing engine with carb cleaner.
A stray spark and you will be looking for a hose, pronto.
Get a fine mist spray bottle and when the engine is running you spray around the manifold.
If the engine starts to die you have an air leak.
the manifold is plastic & cracks and there is an O ring that goes hard & flattens over time.

Also have a look at the control lever on the throttle butterfly.
They are boomerang shaped and one arm of the boomerang hits a stop in the manifold.
They oft get pushed over the stop & end up on the wrong side so the butterfly can not close & the governor ends up working backwards.

i assume by the manifold you mean the plastic pipe that goes from the carb to the piston ?

the oring has been changed and taped so no problem there i think i need to do deep clean
will have to dig out air compressor and carb clean again just in case

i am losing interest in having a go at it played with it 5 times now and not got a lot farther than i was when i started infuriating realy

i normaly work on scrapers most of the time and as such they dont sell for much last one was my own qualcast a very good mower oil changed regular new spark plug,air filter sharpned blade in middle of summer sold for ｣45 and did not have much interest it must be the uk most use electric

Have you checked to make sure the fuel tank is not warped where the carb mounts?

now an update now had another go carb clean for an hour got out my big air compressor and blow through fully for 5 mins more carb and left and another go at the air cheaked the diaphragm and gadget round the right way and put back together

and still the same it does run better but still has the coughing a lot like it needs an ajustment on some screws (if it had any)

after the putting back together i got a water spray bottle and soaked all round the carb and tank with water and it not make any differance so i think i can take from that there is now no air leakes any more

i took the exhaust off and removed the cover so i can see the ? springs and i assume are there any ajustments that i can cheak here ?

and is there any way of playing with the springs on the carb to set it up with out a techometer ?

thanks for the input all of you

and am i right on the manafold being the plastic piece ?

Only if you can recognise 2000 rpm & 3000 prm +/- 5% by ear.
I know I can't.
I can recognise too fst or too slow but every now & then I do one by ear and then pop the tacho on it, rarely any where closer than 10% and that just is not good enough.
Mower tachos are a stuid pric but you can get a timing light with inbuilt digital tacho for less than a mower one just remember you have may have to devide the readout to compensate for the lack of extra cylinders.

angellonewolf said:

... is there any way of playing with the springs on the carb to set it up with out a techometer ?

Click to expand...

If you have a smartphone, you can get one of these free APPs that can measure engine RPM from the sound around the exhaust. The one I use is "Acoustic Tachometer" (Android). You have to experiment it to know when the measurement is reliable. It takes engine strokes and number of cylinder into account so you don't have to convert the numbers.