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Priming issue with a Toro 20043

jeff67's Avatar

Join Date: Dec 2001
Posts: 616

08-13-10, 02:06 PM   #1  
Priming issue with a Toro 20043

When i push the primer button, there is no gas squirting out of the venturi but instead, I believe the air from the primer button is all coming out of a passage just inside the throat of the carb near the primer air passage. I'm not sure but maybe this passage is called the main air jet? It looks like it has a brass insert in it. If I block this passage with a thick wire and push the primer button, fuel will squirt from the venturi. Also the engine seems to run the same whether or not I block this passage, although I probably didn't create an air tight seal around it.
Does anyone know why I have to block this passage to get the carb to send gas up the venturi or how I can fix this? Would it hurt anything to permanently block the passage with something like a piece of a gasket glued around it or would that make the engine run poorly?

The carb is a briggs and stratton 498170 as pictured below. (not an actual pic of my carb)

Other than this issue, the engine runs fine. I have replaced the primer bulb, the air cleaner housing and bowl gaskets, and cleaned the carb with aerosol carb cleaner.

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aj-allen's Avatar

Join Date: Nov 2005
Posts: 467

08-13-10, 07:27 PM   #2  
If the seal between the carb and air cleaner body leaks the carb won't prime. I always use two gaskets to get a complete seal and don't over tighten the bolts it will warp the air cleaner body no seal no prime.


31YTech's Avatar

Join Date: Feb 2008
Posts: 1,263

08-13-10, 07:35 PM   #3  
Hello jeff67,

AJ is right on with the filter base gaskets, If that doesn't solve the issue see below;

You don't want to block any passage, It sounds like your problem may be a non sealing float bowl seal. If the primer bulb can't pressurize the float bowl area the fuel won't be pushed up the venturi into the throat of the carb.

I've seen float bowls installed crooked and when tightened the bottom of the bowl bent inward by the bowl nut, Then when re-installed properly the bottom of the bowl hits the carb before the top rim of the bowl seals thus causing a air leak.

Check/replace the bowl seal and hold the bowl on the carb, Look at the bowl nut hole and see if you have a small gap between it and the carb. If you have no gap the bowl won't tighten on the seal, You can lay the bowl on a flat surface and set a screwdriver handle on the inside over the hole. Give it a couple light taps to bend the bowl back down then check for a small gap again.

Good Luck

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