What cause a mercury 7.5HP to backfire?

A Mercury 7.5HP outboard motor may backfire due to several reasons, including improper fuel mixture, a clogged fuel filter, or ignition timing issues. A rich fuel mixture or stale fuel can lead to incomplete combustion, while a malfunctioning spark plug can cause misfiring. Additionally, air leaks in the intake or exhaust system can disrupt the engine's air-fuel balance, contributing to backfiring. Regular maintenance and ensuring proper fuel quality can help prevent these issues.