Why does my Mercury Engine fluctuate rapidly at idle and then steadies as rpm is increased?
If your Mercury Engine reading fluctuates rapidly at idle but steadies as the rpm increases, the valve guides may be worn.
What causes the Mercury MerCruiser MCM 454 Mag MPI to fluctuate between high and low at idle rpm?
If your Mercury Engine fluctuates between high and low at idle rpm, it could be caused by a blown head gasket between two adjacent cylinders.
What to do if Mercury MerCruiser MCM 454 Mag MPI fluctuates 4 or 5 inches very slowly at idle rpm?
If the reading on your Mercury Engine fluctuates 4 or 5 inches very slowly at idle rpm, check if the spark plug gap is too narrow or if the valves are sticking.
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