Looking for some inspiration instead of exasperation:
Have a Tecumseh Lawnmower (35) with a 3.5 hip engine and Tecumseh carb, problem , stops running after 30 seconds. Now like me , thinking usual, fuel problem, electrical problem, compression problem....so carb stripped cleaned, new needle valve and seat and for good measure a new float, still same problem.
Thought maybe air lock , so tried running without petrol cap on, no joy still stops after 30 seconds, next changed spark plug still stops, checked coil volts okay. Tested compression fine no problem with compression. So drained petrol tank cleaned and petrol pipe, cleaned carb again still no joy. It primes and fires on second pull but just dies after 30 seconds.I have an identical mower so transposed fuel tank, carb, coil onto the mower and same thing happens just dies after 30 secs interestingly my other mower works fine with all the items taken from the non runner. Thought maybe one of the valves may sticking, so checked them there fine. It gives you the impression it is running out of fuel, checked the float bowl when it has stopped and has fuel. Once it stops you can usually start it again but again dies after 30 secs. I'm thinking maybe air leak somewhere , but where I don't know because my other mower runs with the carb, coil, fuel tank and air filter housing from the non runner.
so anyone any words of wisdom