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I have a lawnmower with a 3.5 HP engine. The area of the carburetor around the primer bulb broke so I got a new carburetor. Cleaned out the fuel tank and added fresh gasoline. The mower primed, started and ran a few times. After that I had to put gas into the carb to get it to prime. That worked a few times. After that it would not prime at all. Gave up and got another carb. Installed it and it would not prime out of the box. Both were made in China carburetors. Carburetor number is 795477. Could I be installing it wrong?

Check your seals and make sure you have the gaskets the right way round.

Thanks for your ideas.

Each time I changed the carburetor I used new gaskets. I put the floppy rubber like one on top of the tank and then put the fiber one on top it. That is correct isn't it? Was careful to make sure the holes line up for the screws so as not to damage the gaskets.

I believe you have installed the diaphragm (floppy rubber) and gasket wrong. The diaphragm should be against the carb and gasket against the tank. Post all engine number so I can double check my instructions.

Rivets said:

I believe you have installed the diaphragm (floppy rubber) and gasket wrong. The diaphragm should be against the carb and gasket against the tank. Post all engine number so I can double check my instructions.

Click to expand...

Rubber (diaphragm) goes on the tank side.

MomsMustang said:

Thanks for your ideas.

Each time I changed the carburetor I used new gaskets. I put the floppy rubber like one on top of the tank and then put the fiber one on top it. That is correct isn't it? Was careful to make sure the holes line up for the screws so as not to damage the gaskets.

Click to expand...

Did you clean out the carb....holes, jets, filters etc....

EngineMan you are correct for most carbs, but if he has some Pulsa-Jet or the Choke-A-Matic carbs the diaphragm goes to the carb. That is why I requested the engine numbers.

Briggs and Stratton Genuine 795477 Carburetor

Is this not the carb he is talking about...!

EngineMan said:

Briggs and Stratton Genuine 795477 Carburetor

Is this not the carb he is talking about...!

Click to expand...

Engine number is 9l602-0927-F1

Carburetor is new and tank was cleaned and new gasoline was used.

So is the final decision the rubber diaphragm goes on the tank side?

Take a look at the two videos to see if it is the same carb, my book and info tells me, and the fact that I have always fit them that way, it should fit on the tank side. you can if you wish try both sides and see...!

https://www.youtube.com/watch?v=PMx0ky8A-Fw&html5=1

https://www.youtube.com/watch?v=_pzWNmFoba0&html5=1

I assumed he had a carb like the ones in Sec 3 Page 20 of this manual. My assumption is then wrong and the diaphragm should then go against the tank. Sorry.

https://drive.google.com/file/d/0B6NaqjIxWV1ycG8wd0s3Z2Q2X00/view

That's alright Rivets, for a moment there I was beginning to believe that I was wrong...!:biggrin:

Thanks to everyone for there ideas. The mower started and is running. The problem was not what I expected. The Chinese carburetor came with new screws so I tossed the originals and used the new ones. Turns out the Chinese ones were not machined correctly and tightened up before tightening the carburetor down on the fuel tank. I fixed the threads on the screws with my tap and die set and then they screwed in completely. I guess the Chinese are not real good and machining SAE threads.

The stuff that fails quality control in Chinese factories gets sold off at auction to surplus merchants who on sell it to wholesalers who sell it to online retailers who sell it to you via evil pay or Amazon.
By using these outlets the sellers can hide from you so you don't kick their but black & blue for selling defective parts which you can not do on craigs list.

Rule of thumb.
If the "store" does not have a real presence where you can walk in and buy stuff over the counter and the product you are buying does not come labeled in a labled package then there is a 99.9% chance you are buying defective parts that should have gone into the scrap metal bin.