2005 250 HPDI losing RPMs at WOT

[TonyC444]

Hello to all,

Boat was at repair shop for problem of losing RPMs at WOT. Changed all filters(3 of them), did water pump while it was there and also checked diaphrams. Ran boat yesterday still drops at 5000 RPMs to around 3500-4000. Stop and wait to turn off and then can get back up to around 5500-5600 RPMs. Mech is trying but really not a Yamaha master tech and there is really no one around here that works on HPDI's. Any thoughts? Would Yamaha talk with me about what I could check myself. Maybe a coil braking down or some other electrical problem?

Thanks,

TC

[99yam40]

I am sure if you do some forum searching and reading you will find out what all needs to be tested and how and with what.
Maybe Rodbolt will see your question and type them over again

[rodbolt17]

since the Z motors were introduced about 1999, I have NEVER seen an ign coil failure.
simply fix the fuel system'
monitor BOTH medium pressure and high pressure fuel systems at the problem RPM and load and like magic the solution will appear.

[TonyC444]

It was my primer ball, I replaced it and motor runs great now.