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Bought a used 2013 Xpress X19 with a VZ150 on it in December, Took the boat out a couple half days, then had all the filters changed/serviced along with water pump and lower unit in Feb. Ran fine, idled fine before and after all of this. Was trying to beat a storm back in a few weeks ago with one of my sons after a short trip and the kill switch accidentally got pulled while running about 4500rpms. Got it started back and to the ramp and home we went though it wasn't idling great at the ramp. The next trip out and the motor won't idle without feathering throttle, in or out of gear, but once up on pad she runs great till you come off and try to idle again then kaput. When it will idle for a few seconds it sounds terrible and is at 3-400rpms then dies. Unplugged battery overnight to clear the computer, then tested it on the hose at home - idled and ran fine in perfect rpm range. Problem solved - back to the lake! Nope, once in the water at the ramp the exact same problem. Took it to my mechanic and after a week he can't find anything consistent. He's not a yamaha tech and doesn't have the yamaha software but has a different one, but has worked on these motors before. Says that it will idle on the hose but not in the lake - same problem I had. Problem is there are no faults in the computer and everything he can read is within spec both on and off the lake. Changed plugs, low pressure fuel pumps (failed vac test), tested O2 sensor and TPS, changed battery, cleaned all grounds and contacts. Individually checked injectors and coils both manually and on the software and all are fine, unplugging each one gives a noticeable change so they are all working fine per the computer and actuality. Boat still runs fine when up and running at higher rpms and idles fine only on the hose and our of the water.
TL;DR This tells me that there is something going wrong when there is exhaust backpressure, but once the boat movement through water or prop wash clears that then the problem goes away and the motor is happy. What on this engine can be causing this? I really need a direction to look in. I'm probably about to take it to a Master Yamaha Tech but the closest one is 2 hours from me. Thanks for any ideas from your experience!
TL;DR This tells me that there is something going wrong when there is exhaust backpressure, but once the boat movement through water or prop wash clears that then the problem goes away and the motor is happy. What on this engine can be causing this? I really need a direction to look in. I'm probably about to take it to a Master Yamaha Tech but the closest one is 2 hours from me. Thanks for any ideas from your experience!
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