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HELP! Yammy 300 hpdi maxing out at 4800 rpms and dropping....
UGh! I can't tell you how frustrated I've become, and unfortunately i already took up drinking so that can't be my solution so here it goes: I have a 2005 contender 21 with a 300 hpdi with 500 hours.. I've had the usual issues over the years with filters, screens, vst tank etc, but this one has been plaguing me for a while now and has everyone stumped..
my boat maxes out at about 4800 rpm and maybe 40mph. recently, like today it is down to 4500. it burns fuel and oil however like it is at 5800 rpm and doing 50-55mph..... so heres my run down:
there is not water in the hull.
changed plugs and ALL filters. hooked it up to a computer and no codes. found a bad fuel pump relay but replacing it made no improvement....fuel pressure says its good but bulb is slack and requires a lot of pumping to get it hard. bulb is soft at WOT but not sucked in.
it is not the prop. had a 21 pitch prop originally and the boat was too scary to go full throttle. i took it to the yamaha dealer here to figure out my missing rpms and they attempted to solve the problem with new injectors. Hmmmm- what a surprise it didn't change a damn thing! you would think a couple thousand $ later i might be running better. nope. My dealers solution? put a 17 pitch aluminum
prop on there. WTF? sure it gave me rpms but the boat didn't go any faster in fact the prop would cavitate regularly. Have a 19pitch on now but really want to put my 21 back on but then i will be down to 4000-4200 rpm if I'm lucky.
...related to all this or not- I have a 110gal fuel tank and could only get 60 in last time i filled. gauge said i was full. after leaving the dock fuel level eventually dropped back to half where it should have read. bottomline, could all of my performance problems be related to a venting issue? we ve looked at everything- or at least it feels like it....
The big issue: the boat runs fine. not rough, just won't max out. missing all that high end power. burning lots of fuel and oil like it is maxed out. Suggestions?. I am losing my mind and am on the brink of re powering my boat because i cannot take the frustration any more......
my boat maxes out at about 4800 rpm and maybe 40mph. recently, like today it is down to 4500. it burns fuel and oil however like it is at 5800 rpm and doing 50-55mph..... so heres my run down:
there is not water in the hull.
changed plugs and ALL filters. hooked it up to a computer and no codes. found a bad fuel pump relay but replacing it made no improvement....fuel pressure says its good but bulb is slack and requires a lot of pumping to get it hard. bulb is soft at WOT but not sucked in.
it is not the prop. had a 21 pitch prop originally and the boat was too scary to go full throttle. i took it to the yamaha dealer here to figure out my missing rpms and they attempted to solve the problem with new injectors. Hmmmm- what a surprise it didn't change a damn thing! you would think a couple thousand $ later i might be running better. nope. My dealers solution? put a 17 pitch aluminum
prop on there. WTF? sure it gave me rpms but the boat didn't go any faster in fact the prop would cavitate regularly. Have a 19pitch on now but really want to put my 21 back on but then i will be down to 4000-4200 rpm if I'm lucky.
...related to all this or not- I have a 110gal fuel tank and could only get 60 in last time i filled. gauge said i was full. after leaving the dock fuel level eventually dropped back to half where it should have read. bottomline, could all of my performance problems be related to a venting issue? we ve looked at everything- or at least it feels like it....
The big issue: the boat runs fine. not rough, just won't max out. missing all that high end power. burning lots of fuel and oil like it is maxed out. Suggestions?. I am losing my mind and am on the brink of re powering my boat because i cannot take the frustration any more......
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