I have a Toro GTS5 Super Recycler mower model #20487. I recently changed the oil, plug, gasoline, air filter, primer bulb, and cleaned the jet in the carb. When starting the mower it starts and then shuts down after about 3 seconds. It will stay running if I continue to prime the mower. Everything I have read references cleaning the jets, but mine is free of any blockage. Any thoughts for me? Thank you.

Hi ricks7...
I also believe that it is a problem with the jets.
Try some of these solutions
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Check/Clean/Replace your fuel filter if you have one, normally they are located in the fuel tank of weedeaters.
Also make sure you are using fresh fuel...and oil mix if your using a two cycle mower or weedeater with the oil to the right mixture and not too much oil as it can cause hard starting.
If the mower/weedeater is over a year old, then I recommend that you buy and install a new carburetor repair kit,because the diaphragm will get hard and that will cause it to be hard to crank.
Sounds like you will need to clean the carburetor or replace your carburetor internal rubber parts like the diaphgram and O rings.
I recommend that you use a laquer thinner type cleaner to clean and dissolve the laquer build-up in the float and needle jet passages.
Be sure to remove all plastic and rubber parts before using the laquer thinner because it can dissolve the plastic parts and render them unuseable.
Be sure to use compressed air to blow out all the fuel and air passages.
Be careful when blowing out the passages, because there are sometimes small rubber type seats in the bottom of some of the passages.
Sometimes you can get by with priming the carburetor or using starting fluid and letting it run a few times like that and it will flush the gunk out of the jets,but most of the time you will need to rebuild the carburetor.
Keep in mind that the float for the carburetor must be level when you go to reassemble the carburetor or follow the instructions you get with the carburetor kit.
When you clean your carburetor and remove the jet screws, you will first need to lightly seat the jet screws.
But before you lightly seat the jet screws count the number of turns it takes to seat the jet screws from their original position.
Be sure to mark the turns down on a piece of paper.
That way when you put the jets back in, you know to lightly seat them first and then turn them back out to their orginal position before you started.
Once you have your carburetor rebuilt that should solve your problem.
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