18.5 HP B&S riding mower starts fine, dies suddenly

[Walt 2002]

" why would it prevent the engine from turning over when he tries to start it?"

"For the same reason why it stopped in the first place. Vacuum pressure in the fuel tank (caused by a clogged vent hole in the cap or a broken vent/cap) preventing the flow of gas to the fuel pump. After the machine sits awhile, the vacuum pressure dissipates and fuel flows again. This is a very common problem, and the symptoms are almost identical every time."

In over 60 years of working with small engines, I have never heard of this preventing the engine from turning over, cranking as the OP said.

Walt Conner

[Harryc]

Well Walt, I misread the OPS first post, so your 60 year experience is intact .

[Bruce]

I'll take an off the wall guess at this and I think it could be narrowed down somewhat with some multimeter testing. I am going to say that one of the safety switches, connections or wiring is the culprit. The safety circuits can control both the engine ignition (grounding it out) and 12 volts to the starter - Bruce

[sherlineB]

I think, you better check the engine.