Briggs & Stratton 725E series wont prime

[wolf8963]

Hi, Im a novice in working on small engines.

I will give some background information - I dont think most of it is pertinent but just in case...
Im dealing with the engine above on a Murray push mower.
The mower was my brothers - it stopped working from one week to the next a year or two back, and then sat. I am trying to get it running so we can use it to mow my mothers lawn without having to drag a mower back and forth.

It had no spark - I think this was probably the original problem. I replaced the magneto and it now has spark, but still couldnt get it started.

Injecting a little gas into the carb would allow it to run a few seconds but even doing it repeatedly wouldnt allow it to run.

At that point I pulled the carb and cleaned it and discovered the holes in the screw holding the float bowl were completely plugged. Cleaned all orifices thoroughly following a video from our friend youtube, Verified the gas line was clear, etc.

At this point I was able to get the mower running by injecting some gas in the carb. And I could shut it off and restart it within a couple minutes with no problem. However if it sat very long, it was back to not starting without injecting gas. Clearly it was not priming - I looked in the carburetor while I pumped the bulb and no soap.

At that point, again following youtube guidance (sorta), I pulled the airfilter housing, pulled the bulb, and cleaned everything very well. The bulb looked fine. This is the type of primer assembly where the bulb is built into the filter housing with the tube part of the housing molding. It has a 'J' shaped channel on the area under where the filter sits. I verified that channel is clear and I could spray brake cleaner from the bulb side (with the bulb removed), and it came out the channel.

Once everything was reassembled I replaced the original gasket between the air filter housing and the carb with one I cut thick, high temp, gasket material sheet - with the idea that the extra thickness would be like putting on a double gasket. Then re-assembled everything and tried it.

No soap. Tho I pumped the bulb 200 times at one point, I never saw any gas shooting into the carb, and I couldnt start it without injecting gas into the carb.

Does anyone have any ideas? Ive tried all the tricks Ive been able to find but havent been able to fix the primer problem.

Thanks for any help you can offer!

 

[bertsmobile1]

Starting from the top.
Some primers squirt fuel directly into the carb
Other depress the float to raise the fuel level
So we need to know the full engine number which will be on the rocker cover or the heat shield above the muffler.
Next if it is an OHV model, check the valve lash.
If it starts easily with fuel dumped into the spark plug hole & does not start easily with fuel dumped into the carb then check the long manifold that the carb sits on.
IT goes all the way across the engine and is prone to cracking

 

[wolf8963]

Starting from the top.
Some primers squirt fuel directly into the carb
Other depress the float to raise the fuel level
So we need to know the full engine number which will be on the rocker cover or the heat shield above the muffler.
Next if it is an OHV model, check the valve lash.
If it starts easily with fuel dumped into the spark plug hole & does not start easily with fuel dumped into the carb then check the long manifold that the carb sits on.
IT goes all the way across the engine and is prone to cracking

Thanks for the fast response.

The number I think it is is:22M02-6377-F4 - does that sound about right? There are 3 Chars under that number as well that are very hard to make out - It might be DOT or DOF or DO1 (or something else) but it does not look like OHV.

In regard to the starting, it starts very easily with gas dumped in the carb tho you might have to do it twice to have it keep running.
thanks

 

[wolf8963]

Thanks for the fast response.

The number I think it is is:22M02-6377-F4 - does that sound about right? There are 3 Chars under that number as well that are very hard to make out - It might be DOT or DOF or DO1 (or something else) but it does not look like OHV.

In regard to the starting, it starts very easily with gas dumped in the carb tho you might have to do it twice to have it keep running.
thanks

looks like I missed part of the number. After the F4 and a space, there is 13041956.

 

[bertsmobile1]

number Looks wrong
a 22 is 22 Cu inch which would be around 10 Hp.
11 or 12 would be about right for a push mower 6 Hp
Looks like you missed the 1 as 122m02-6377-F4 is a good number
FWIW the serial number 13041956 is the date of manufacture 2013 -04-19
And yes it is a side valve engine.

According to the parts book you have the early primer which pumps fuel.
However these backing plates are notorious for warping .
Some times double gaskets will do the trick, some times they won't

 

[wolf8963]

hmm what do you think about a little gasket compound all around the outer edge to seal?

 

[gainestruk]

If the primer bulb will come out I would replace it with a new one, I had fits with an old feather light weed eater, I finally changed bulb and it ran fine, I never could find where it was leaking on old one.