300 HPDI Wont Idle

[perryk123]

Runs kinda rough on the garden hose in gear at idle. Will accelerate and act ok, but when you bring it back to idle, it just dies. In the water it wont idle at all, you have to rev it up to get it in gear and it will run wide open, but as you slow down close to and idle, she dies and will not restart for a few hrs.

opened and cleaned vst (was very clean inside), replaced filter, fuel lines, and diaphragm pumps, check psi on vst all good. ran on test tank same problem

cleaned air intake found some dirt and gunk stuck in there

replaced battery just to be sure it was not a voltage issue

compression is 120 psi on all cyl

checked spark with an in line spark tester, and all cyl are firing

vz300 tlrc 2004 model on a Skeeter bass boat.

any help would be greatly appreciated.

We dont have a Yamaha dealer that really knows them around here, just part changers.

[Inducted]

You can try syncronizing the throttle valves. Also adjust your TPS. If your yamaha dealer has YDIS they can check your high pressure fuel pressure, very simple diagnostic test if the technician has any training. It might be an injector issue?

Do the tv syncro and tps first.