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Old 04-02-2012, 11:32 AM
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Default mercruiser 454 loss of fuel pressure

having same problem as before. Engine starts fine when cold. After 15 min engine quits. Connected fuel pressure gauge and presure reads 32psi. after a short time drops to zero,engine dies. Scan tool shows no codes.Turn key 3-4 times and peressure comes back up engine starts runs for a min or so same thing. Replaced high pressure pump last year and install eletric fuel boost pump. found mechanical lever worn thin and salt water pump that drives the mechanical pump had the lob that drives the pump spinning free when engine is stopped. Is that normal? How does the mechanical pump spring lever get lubricated? Does the high pressure pump run all the time when the engine is running?How much pressure does the mechanical put out? Have checked the vents as well. Also checked spark as well Good spark. Just no fuel.
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Old 04-02-2012, 05:34 PM
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Not sure about your wiring BUT, there should be an oil pressure switch that turns on the pump with oil pressure. Engine stalls, pump shuts off. It's a safety feature. The switch does fail on Mercruisers.
If you find the switch you can put a jumper on the switch to TEMPORARILY check it.
Turning on the key runs the pump with a relay for a few seconds to prime the system.
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