225 Yamaha Four Stroke - Dies at idle

[mezemeze]

My 2004 port engines starts fine after priming the bulb, run at idle for 20 minutes, run engines for 20 to 50 min at 2000 to 5000 rpms, idle for 3 minutes or so to anchor. Anchore for an hour. Restart successfully, idle for 3-5 minutes, increase throttle to around 1500 rpms, engine dies. Engine also died recently after running at 4000 rpms for 60 minutes, then throttled back to 1500 rpms or so for about 5 minutes, engine died. Prime the bulb after each failure, and I am on my way again until the next failure.

Mechanic performed pressure test (42 psi), at start up and with engines running, pressure test did not identify any issues. Mechanic replaced Main Relay because of heavy corrosion on pins. This did not solve the problem.

I purchased the boat in November of 2014, at which time I had the tank drained and vacumed, sending units were replaced with perfect seal, changed inline fuel filters, changed element filters, changed fuel water separator filter, changed oil and spark plugs - in December of 2014.

Any help would be most appreciated.

[TownsendsFJR1300]

The rail pressure should be checked when its acting up..

[Nautical]

Fuel related would be my guess. Sticking fuel float /needle valve is another .

[mezemeze]

Problem Fixed

The mechanic replaced the Low Pressure fuel pump and relief valve. Which was most likely the causing the engine to die at 1200 RPMs, or below. Before replacing these components we took the boat for a test run, with the computer attached to the engine, and a pressure gage attached just before the rail. We ran the boat at 4000 RPMs for about 15 minutes, then idled for 10 minutes, shut the engine down for 5 minutes, started it back up, and idled for 10 minutes at 1200 RPMs before the engine died.

Having the engine open, he also removed the High Pressure Pump, and cleaned the VST Cup and Pump Screen, and he replaced the gasket.

I idled the boat for over 2 hours, it is running great.

Thanks again to those that responded.
This forum has helped a novice like me, speak a little more intelligently when interfacing with the mechanics.