7MGE No-Start After Top-End Rebuild - Distributor Rotor Misalignment

Electricalintermediate✓ OP Confirmed

Problem

7MGE engine would not start after a top-end rebuild (valves, seals, gaskets replaced, valves lapped, clearances adjusted). Engine had spark and fuel but would not fire. An explosion/backfire occurred during spark testing at plugs 1 and 2.

Engine cranks but will not startBackfire/explosion during spark plug testingStrong smell of petrol on spark plugs after crankingSlight misting of oil on plugs initially (cleared after cleaning)No diagnostic trouble codes present

Root Cause

The distributor rotor was not properly aligned with the #1 cylinder lead. When the distributor was installed, the distributor gear caught the camshaft gear and rotated slightly, causing the rotor position to be offset. This meant spark was being delivered at the wrong time relative to the piston position, preventing combustion and causing backfires.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted October 2019 on SupraForums.com