145 Automatic surging

[02chuck1]

I bought a 145 ( it has the v-twin Briggs motor) and after using for a short while it started to surge, pulling the choke back would keep it running, then it just died.
I researched older posts and went stepped through the trouble shooting steps recommended.
Rebuilt the carb (sprayed carb cleaner through all the jets and passages till they sprayed well), bought and replaced the orings on the jets in the fuel pick up, replaced fuel pump, air and fuel filters. Had to buy that little hose for the vacuum pressure to the fuel pump. Took it out for a test mow, after about ten minutes of running I felt it start to surge again and it repeated what started me on the journey.
What am I missing?
Thanks

 

[weathda]

Could be a vacuum on your fuel tank? Make sure you fuel cap is venting. The caps have a small hole that's easily plugged. You'll pull a vacuum on your fuel tank and it will result in the exact symptoms you describe.

Easy enough to check, when it starts surging, loosen the fuel cap.

 

[02chuck1]

I'll give it a check. That would be way to easy.
thx

 

[02chuck1]

Finally got back to trouble shooting the beast. Went through the carb again to see if I had screwed up. Nothing. Did notice that there wasn't any gas in the float bowl when pulling it apart.
Put the carb back together and back on the mower. Made sure I had gas in the tank. Had my wife come out and crank the mower while I had the gas line off the carb, even hit the intake with carb cleaner to
get it to run a bit. no fuel out and no fuel pulled into the filter. Pulled the new pump and reinstalled the old one. Repeated the process of cranking the engine and running it with the carb cleaner.
Surprise!!! Gas coming out the line and a full filter. Put the fuel in on the carb, had wife crank the engine and got it running on the carb cleaner till the float bowl was full and it runs!!!
Finished putting the shroud on and took it out and it ran like a champ!!!!
Now the electric clutch for the blade is not engaging after mowing for a while, on to the next challenge.
C