There it was. A dark flake of gasket material sat near the float arm, hardly larger than a grain of rice. At rest, the arm seemed free; as it moved through one particular section of its travel, the debris trapped it and prevented the needle from seating. Fuel had continued to enter when it should have stopped, leaving the cylinders too wet to fire cleanly. Nolan's cleaning had missed the intermittent obstruction because he had not tested the movement through the full angle.
Owen eased the fragment out and held it between his fingertips. "Float arm was catching," he said, not to the crowd but to himself. "It wasn't controlling the fuel."
Nolan made an involuntary sound. "I checked that. I checked that float twice."
"I believe you," Owen answered without looking up. "It moves when the bowl's held flat. It catches when the angle changes. That's how the flake stayed hidden."
The reply contained no triumph, and that made it more difficult for Nolan to bear. He had expected the boy to mock him and was prepared to defend himself against a mockery. Instead he was being offered a precise explanation of what his check had failed to reveal. His face reddened beneath the garage lights.
Owen remembered a late-seventies field advisory he had found in a library binder of old service information. It described a similar clearance issue on replacement carburetors used by owners of older motorcycles. Thomas had penciled a note beside the photocopy years before: DON'T TRUST ONE POSITION. The words flashed through Owen's mind as he checked the float again and confirmed it returned smoothly each time.
He wiped the edge of the bowl, reseated it, and secured the fasteners. The float moved freely now. The fuel system would no longer keep drowning the engine. Owen set down his screwdriver and glanced at the watch held high near the folding table.
Two minutes and ten seconds remained. Garrett had been expecting the boy to waste the clock with nervous fumbling. Instead he had watched two diagnoses turn into two completed repairs, and the knowledge pressed against something inside him that had gone unchallenged for years. He told himself the boy had guessed. He told himself the mechanics had been careless. He told himself the remaining fault would stop the machine anyway.
"Two down," Owen said.
Garrett stepped between him and the table. "Don't you get smug with me. You think that because you memorized some old manual you're special?" He pressed a finger hard against Owen's chest. "A book doesn't make you better than the people who've spent their lives doing this."