Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer

Toddo77

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Walmart HyperTough Brand - Briggs & Stratton Engine 300E Series - Date Of Manufacture 6/2018

Model No. 08P502-0111-F1

This lawnmower was only running right for 1 season. The engine only had like a max of 5 hours on it total. Symptoms started up going into the second season/year.

Symptom 1 - Sputtering at first

Checked Air filter. Air filter OK. Check spark plug. Looked OK. Went ahead and hit the spark plug electrodes with emery cloth. Seemed to run a little better.

Symptom 2 - Two weeks later. Started OK and ran OK for half an acre then started sputtering then died completely. Sounded just like it ran out of gas. After this the mower would only start then die. I had to push the primer bulb 3 or 4 times each time to get it to start, but would die right after starting. The engine would run on primer gas only.

Checked air filter. Check spark plug and spark plug gap. Pulled off float bowl and emptied it in case there was water in there. No joy. Check valve gap and valve gap was .008. I left that alone. Seemed like something was preventing it from getting gas. So I then pulled the carburetor and just looked around to see what I could see. I pulled what's called the "main Jet" and got my magnifying glasses on and looked at all the holes in the main jet apparatus. Seemed like I could barely see something in one of the jets. I got a sewing needle cause that's the only thing thin and pointed enough to get into the jet holes and wiped this out of one of the jet holes:

uvSGz28.jpg


It's a very thin sliver of black plastic I think. I'm figuring it some kind of manufacturing debris. Either from the manufacture of the carb itself or the black plastic fuel tank. It was so small I could barely see it.

Here's a pic of the main jet. I think I pulled it out of the one circled in red:

If60sAG.jpg


Tip for anyone with this engine and these symptoms. When you pull your carb apart and examine the main jet, if you can't see daylight at the bottom of any jet hole, it's got debris in there blocking it. When you hold the jet up to light and look down through the hole you should see daylight.

Lawn mower now runs fine. That teeny tiny sliver of plastic in a jet hole caused the problem. This carb is still better than the one my old lawn mower had. My old mower had a Briggs & Stratton where the carb was bolted to the fuel tank and it had that diaphragm between the tank and the carb. That diaphragm thing had to be replaced every 5 years or so. The carb in this engine basically has nothing to replace. Just need to check and clean the jets holes when it starts acting up.

Here's an exploded view on the carburetor. I got it off Jacks Small Engines

wIntgww.gif
 

dougand3

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Re: Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer

Good write up.
 

Toddo77

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Re: Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer

Good write up.

Thanks. My aim is to help other poor hapless peeple looking for answers....
 

JKQ

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Briggs&Stratton 300E seriesE,Model#08P502-0111-F1 Engine
What is the white port on the Carberator upper side facing engine for? It has a barb like possibly a hose connected to it if so where does it go?
 

JKQ

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Where can I find a service manual for a Briggs&Stratton 300 seriesE 125cc Model#08P502-0111-F1 ?
 

Rivets

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
To my knowledge Briggs does not publish a manual for the E series engine.
 

JKQ

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Mr Rivets,Thanks for your time,Im trying to find valve settings and armature gap.I know this motor appears to be the throwaway type but Im trying to fix for an neighbor and direction to where I can find info on this engine would be greatly appreciated
Also your username reminds me of the old steamship days which I had the privilege to take a T2 tanker to India,All rivet hull
 

slomo

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Mr Rivets,Thanks for your time,Im trying to find valve settings and armature gap.I know this motor appears to be the throwaway type but Im trying to fix for an neighbor and direction to where I can find info on this engine would be greatly appreciated
Also your username reminds me of the old steamship days which I had the privilege to take a T2 tanker to India,All rivet hull
Your manual is below. Click on the Briggs Europe link.



22.PNG
 

JKQ

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  • / Briggs & Stratton 300E Series Engine Starts Then Dies - Will Only Run On Primer
Thank you sir! for the help.
 
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