Briggs and Stratton 500 series lawn mower throttle or other problem?

My B@S mower kept getting harder to start last year but we dealt with it. Last week I couldn't even get it started but 3 times only for 5 to 10 seconds each time. Well after watching some very detailed YouTube videos I changed the oil, spark plug, and cleaned the carburator-the diaphragm seems still good with tabs intact. Now it starts every time but runs very rough after the first few seconds and dies after a couple of minutes. Any leads? Thanks in advance

 

The diaphragm should be replaced, especially if you already had it out. The "tabs" aren't the problem area. It's the thin spot under the intake tube that pulls out and wrinkles a little that causes problems.

 

It does have a loosened bubble type thing going on. lol. Thanks!

It also seems like the throttle does nothing. Ive watched several videos looking at the spring placemenet, which I didnt disturb, and my set up looks identical but the bigger spring is a bit loose. Thanks again for helping a rookie out

 

Do the diaphragm first and see where you are after that. The spring only affects engine rpm, so it will either run fast, slow, or just right. It should be loose right now, only having much tension on it when it is running.

 

fixed the diaphragm and it ran like a dream, better than ever!

Mowed over half my back yard and then it started sputtering and died. I took it to my porch to see if I could figure out what had suddenly happened. As it was barely running a couple of starts in a piece of metal falls out. It was the metal post where the fan baffle? closes under load. It sheered right off.

So I guess now I get someone to either weld this obviously older than I thought used lawn mower back together or I give up and buy a new one that wont keep falling apart. LOL! Thanks for your help though, at least I got the satisfaction of fixing it myself. Its like rebuilding a car motor and driving it around perfectly until the axl breaks. lol

 

The throttle on top of the carburetor? If so, you can take it out and replace it with another. Most small engine shops will have some junk carbs to remove the part from, or a new one is only a few bucks. It's about as easy to replace as the diaphragm.

 

Thanks Cheese but no, this was the actual piece of metal that the fan(where the pull string is) arm/baffle/thing that adjusts under load uses to keep load pressure. Now that this piece of metal has sheered off at the base the baffle/arm has no way to harness the load pressure output by the engine and thus dies after a few seconds of running like crap. When properly still intact on the engine its the vertical 3"ish piece of metal that the baffle/arm closes on under load next to the fan/flywheel spindle.

Again, rookie here so idk the proper names

 

Okay, the bolt that holds one side of the coil/armature and goes through the hole in the governor vane? If it broke off, take the coil off and the rest of that piece will probably be sticking up where the coil legs was covering it and you can unscrew it and replace it. Unless the aluminum part under the coil is what broke.