After much frustration, my '03 115 hp Yam inline 4, 4-stroke is diagnosed with a bad ECU. This little computer/solid state wizard is around $1000-1200. The tech talked to Yamaha and was told that some of the ecu's "delaminated??" internally due to heat or vibration. MY BURNING QUESTION IS...
What would cause the fuel rail pressure to behave as follows: ENGINE RUNNING: pressure per shop manual, around 32-35 psi). ENGINE NOT RUNNING, KEY ON: very low pressure, 5-10. We can hear the pump run when the key is turned on and when we took out the high-press fuel pump and tested it in a...
Our o3 Yam 115 inline 4, 4-stroke seems to run fine in the boatyard, revs up, no problems. In the water, under load, won't go beyond 3500-4000.
Increasing throttle at those speeds even seems to slow the engine a bit. Can get occassional bursts of speed above 5000 but does not stay there. Yam...
