Had the boat out over the weekend. Ran fine in the morning and as I was running to a new location I noticed the RPMs dropping from 5500 to 3500. After stopping the boat I tried again and it did the same thing. Any suggestions?
The engine is a 2005 Yamaha 250 HPDI.
Possible fuel restriction. Injectors ever been serviced? Vst filter? I would start with the easy stuff first, replace filters.
Ranger Z21/Yamaha HPDI 250
Looking like it's the mystery filter. Thanks for the reply.
so, was it actually the HP (mystery) filters? Prob solved?
Finally had the problem resolved. We originally replaced the mystery filters but after taking for a test run we determined the problem did not go away. After additional test, the med lift pump was failing causing the engine to lose 20 psi. By running the engine with the fuel issue, it caused an additional problem. Because the engine was running lean and therefore hot the exhaust manifold had deteriorated, about 10 inches of it. Mechanic said the exhaust issue is rare but happens. Anyway, I hope this helps others who might be experiencing the similar issues.
Thanks for the follow up post sir... good info. Good thing you did not pop a cylinder running lean... that's what happened to me... Best of luck going forward...
Actually the tuner issue is more common than you would think. Cj
2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.
Can you explain what the med lift pump is and where it is located? Thanks!
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