This one has me stumped

[Tinkerer200]

Try your old diaphragm or rob another one out of one of your kits.

The type tank/carb you describe generally has an open topped bowl just below the top of the tank. Your diaphragm fuel pumps gas up into this bowl which overflows back into the tank. The bowl stays at a constant level and the carb draws gas from this bowl so no float. When the tank is full, it fills this bowl without diaphragm fuel pump. When you tilt mower back or push back and forth with tank nearly full it will slosh gas into this open bowel or cup. Sounds like this bowl, cup is not being kept full. Hole in pickup tube as said, hole in open top bowl (not likely) problem with diaphragm fuel pump, likely.
Walt Conner

 

[Scrubcadet10]

Diaphragm and gasket in correct order?

 

[Fish]

Sounds like a little bit of water in your carb.
Post your engine's model numbers so we know what you have.

 

[bbest]

Sounds like a little bit of water in your carb.
Post your engine's model numbers so we know what you have.

No water.

 

[bbest]

It appears I have found the problem. It was not the carb. This particular Briggs has the long governor rod. The cover was slightly bent.causing it to bind slightly. I did as I said, recleaned everything, reassembled, and now it is running as it should. I did install another new diaphragm. As to whether that had anything to do with it...I do not know. It was perfectly clean when I took it apart, and perfect when I put it together. All is well in the universe now...Thanks guys! Maybe there was a piece of something somewhere that I knocked loose, unsure, but the governor rod getting stuck was the only thing I saw that needed correction...

 

[seattlepioneer]

<<It appears I have found the problem. It was not the carb. >>

I think there is a tendency to have a theory on a problem, and pursue that repair repeatedly even when it doesn't fix the problem. Part of that is lack of confidence that you have fixed the problem correctly.

But you can fix the carb as many times as you like, and it's not going to help if something else is the actual problem.

I've replaced a part on a furnace I was repairing with a new part, but had exactly the same problem upon replacing the part. I sweated bullets trying to identify the actual cause of the problem.

Ultimately I found that the NEW part had the exact same problem! I had accurately diagnosed the original problem being no good, but I lacked the moral courage to repeat the same diagnosis for the brand new, right out of the box part!

 

[slomo]

Sometimes, new parts, are not, new parts. Like this, I dropped the spark plug getting it off the counter. Installed it in the engine and it still doesn't run. Then people come here and say they put a new plug in. Just typing out loud here. Glad it is working for you. Replacing carb parts like that builds character.

slomo

 

[seattlepioneer]

<<
Replacing carb parts like that builds character.
>>



Good or bad?

 

[Rivets]

How about posting the engine numbers and the part number for diaphragm and gasket. I’ve got an idea for a solution, but until I know your engine I’m not going to muddy the waters.

 

[greynold99]

Just a quick tip - I'm running a similar post on this forum for a Weedeater 500 push mower that runs only on gas poured through the carb... Not sure it applies to your situation but two things I was given to check...
1. Roughen up the mounting-metal on the front surface area on the top of gas tank where carb mounts and seals the diaphram - apparently there was an air-leakage issue with the design;
2. Check the intake-gas cylinder tube for cracks - where the rubber boot from the carb connects to the engine; if plastic, it may be cracked.

Looks like any place air can enter the the gas supply flow would need to be checked.
greynold99