Export thread

I prime this engine and pull starter and it will run for a second and then quit. As long as I keep pushing primer button it will run.

Likely to be dirt in carb or diaphragm.
Give the carb a clean and replace diaphragm briggs 795083.

pugaltitude said:

Likely to be dirt in carb or diaphragm.
Give the carb a clean and replace diaphragm briggs 795083.

Click to expand...

Thank you for the info. I have gave the carb a through cleaning and now will look for a new diaphragm. Again thank you.

FredMacaw said:

Thank you for the info. I have gave the carb a through cleaning and now will look for a new diaphragm. Again thank you.

Click to expand...

I installed new diaphragm, cleaned carb again and flushed out tank. Still same problem. Thank you.

Re: Briggs & Stratton; 550 series; 158cc

FredMacaw said:

I installed new diaphragm, cleaned carb again and flushed out tank. Still same problem. Thank you.

Click to expand...

My Yard-Man has a 158cc Series 550 Briggs

I was plagued by this problem for about a month and after taking off the carb more than once and cleaning and blowing out all the ports and passages without good results I concluded that this carb was defective and bought an new OEM carb. SAME PROBLEM! I needed to determine if it were a lean or rich problem as I was certain of having spark and compression. Started it and waited until it started to stumble, just before it stalled I gave the little priming bulb a squirt. It immediately caught again but only for a second and then started its stumblingly way back toward a stall which I could catch again with another squirt. OK, BRAND NEW CARB AND IT RUNS LEAN! WTF! In frustration I gave it a really hard squirt that depressed the bulb all the way in. It came back, but now was sounding that rich, farty, rough running way, like when you choke a motor too much. But it almost immediately came back to normal run. AND it kept running! So now instead of the 3X pushes they say to give it, I push the priming bulb until I actually feel a resistance and the sound of pumping/squirting fuel and THEN I give it three solid, long, hard pushes. It may not start on the first pull as it is now a bit flooded but once it starts, it keeps going. My theory is that fuel drains out of someplace within the carb body and never gets completely re-primed unless you really pump that bulb. Hope this helps.

Cracked inlet manifold? Leaking carb o-ring?

LawnmowerJustin said:

Cracked inlet manifold? Leaking carb o-ring?

Click to expand...

O-ring does tend to hang on the intake when you remove the carb. Be sure to remove it and seat it inside of carb bore engine side. Don't know how you could crack the intake but that would lean it out.

Forceful priming, as mentioned earlier, doesn't require any dis-assembly and should be the very first thing you try.

Re: Briggs & Stratton; 550 series; 158cc

jgreathead said:

My Yard-Man has a 158cc Series 550 Briggs

I was plagued by this problem for about a month and after taking off the carb more than once and cleaning and blowing out all the ports and passages without good results I concluded that this carb was defective and bought an new OEM carb. SAME PROBLEM! I needed to determine if it were a lean or rich problem as I was certain of having spark and compression. Started it and waited until it started to stumble, just before it stalled I gave the little priming bulb a squirt. It immediately caught again but only for a second and then started its stumblingly way back toward a stall which I could catch again with another squirt. OK, BRAND NEW CARB AND IT RUNS LEAN! WTF! In frustration I gave it a really hard squirt that depressed the bulb all the way in. It came back, but now was sounding that rich, farty, rough running way, like when you choke a motor too much. But it almost immediately came back to normal run. AND it kept running! So now instead of the 3X pushes they say to give it, I push the priming bulb until I actually feel a resistance and the sound of pumping/squirting fuel and THEN I give it three solid, long, hard pushes. It may not start on the first pull as it is now a bit flooded but once it starts, it keeps going. My theory is that fuel drains out of someplace within the carb body and never gets completely re-primed unless you really pump that bulb. Hope this helps.

Click to expand...

Depending on year Briggs had a problem with the nickel jet dislodging and falling out of bottom of carb.

That could be the problem.

jgreathead said:

O-ring does tend to hang on the intake when you remove the carb. Be sure to remove it and seat it inside of carb bore engine side. Don't know how you could crack the intake but that would lean it out.

Forceful priming, as mentioned earlier, doesn't require any dis-assembly and should be the very first thing you try.

Click to expand...

The intake manifold is made of 'plastic' so a decent knock on the air filter assembly will do it. And for the average home owner the air filter cover also makes for a great hand hold when picking up the mower and often results in a cracked inlet manifold.

I find that most manufacturers are overly optimistic on the "3x" priming for cold starts. I often go 4-5 to ensure that the mower will start on 1st or 2nd pull. I've serviced and sold several of these B&S 500 series engines and always use the aformentioned priming method.