Engine Cranks Over But Will Not Start Or Starts Hard; Important Information; Fuel System Rich; Fuel System Lean - Mercury MerCruiser MCM 454 Mag MPI Service Manual

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TROUBLESHOOTING

Engine Cranks Over But Will Not Start Or Starts Hard

1. First, determine which engine system is causing the problem. To make an engine run,

basic components - fuel, spark (ignition), and compression - are required. If all three

components are present, the engine should run. If any one of the three are missing,

weak, or arriving at the wrong time the engine will not run.

2. Check ignition system operation. Remove coil wire from tower on distributor cap. Hold

coil wire near ground and check for spark while cranking engine over. Repeat procedure

with spark plug wires. If there is spark at the spark plug wires, remove the spark plugs

and make sure they are correct type and heat range, and not fouled or burned.

3. Run a compression check on engine to make sure the engine is mechanically OK.

Clogged flame arrestor

Excessive fuel pump pressure

Fuel pressure regulator defective

Empty fuel tank

Fuel shut-off valve closed (if equipped)

Low grade or stale fuel

Water in fuel

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SERVICE MANUAL NUMBER 23

Special Information

Engine will not start after warm engine

Special Information

90-861326--1 MARCH 1999

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