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Yamaha HPDI 250 top end ISSUE
I have a Yamaha HPDI 250 280 hours total with 20 ish on a new power head rebuild. I have been through several fuel problems since I first bought it. Recently I changed the mystery filters in the HP pump and a coil due to a plug fouling and losing power on the top end. That fixed my problem, two months later I’m having somewhat the same problem again. After it Sat for a month due to have the steering rebuilt, first trip out it was like it hit a wall and cut out and then it ran WOT, but every trip after that it’s been this problem. It takes off great and runs great all the way to the top end (5000-6150) then it slowly starts losing rpm (power) and then sometimes it won’t go past 5000 rpms. I’ve cleaned the vst filter, high pressure filter was replaced the first time it messed up. Low pressure pumps were replaced last spring. And mystery filters were replaced A month and a half ago. Injectors flow tested when rebuilt. Compression is good, new plugs, fuel line Replaced 2 years ago, had a computer hooked up to it and it showed 0 codes. I have pulled the plugs every time since it first started and the same cylinder that had a bad coil (#3) the plug is constantly wet with gas every time I pull it. I’ve swapped injector drivers around, coil packs, had injector flow tested and showed good. Haven’t been able to get anyone that has the yds to hook it up while it’s running and watch the fuel pressures. I’ve been chasing my tail all year on this thing any help would be greatly appreciated
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Sounds like fuel, start with lift pumps. Replace with Electric pump. Replace fuel lines and add water separator / in line filter.
I feel your pain, those are good Hours though.
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Change the strainer filter. You fixed it yet?
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