pulling my hair out over a 300

J

john hart

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Joined
Aug 27, 2009
Messages
8
looking for any help i can get im working on a 2005 300 yamaha the problem that im having is that the motor will go to about 3000 rpms then shut down it will restart and at sometimes will go as high has 4000 rpms it will only stay there for a while all filters and strainers have been replaced pull pumps rebuilt medium pump shows 50 lbs motor not running plugs or new any help you can give me thanks
 
R

rodbolt

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Sep 1, 2003
Messages
20,066
Re: pulling my hair out over a 300

check BOTH fuel system pressure AT the problem RPM.
medium MUST maintain 50 PSI at any RPM and the high pressure should stay around 1125 PSI at ALL rpm ranges.
bad lift pumps or a fuel restriction between the lift pump intake and the liquid level in the tank can lead to a loss of the 50 PSI which will lead to a loss of the 1125 PSI side.
if yours still has the check valve between the lower lift pump intake and the engine filter cup,remove it,unscrew it and dump the guts and reinstall the body.
look at the oil pump arm and post the numbers you see on it.
also post the engine seriel number.
 
J

john hart

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Joined
Aug 27, 2009
Messages
8
Re: pulling my hair out over a 300

rodbolt thanks for your response im sorry it took so long getting back to you but i had a doctors appointment out of town you asked what the number was on the oil pump arm it is 6d002 the ser # and model#is z300txrd 1002003 i did put a fuel pressure gauge on the med pump put it in the water and at high rpm we had a pressure loss down as low as 20 lbs the two pull pumps have been rebuilt the check valve between the bulb and the filter has no guts in it do you think i should replace the pull pumps or the med pump or all of the above again thanks
 
R

rodbolt

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Joined
Sep 1, 2003
Messages
20,066
Re: pulling my hair out over a 300

typically if the medium pressure pump runs its ok.
I would suspect the lift pumps or a fuel restriction or an air leak in a fuel line or fitting.
if the VST gets low on fuel pressure falls rapidly on the medium side which causes a drop on the high pressure side.
 
R

rodbolt

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Sep 1, 2003
Messages
20,066
Re: pulling my hair out over a 300

on your oil pump, run by your local Yamaha dealer with the arm numbers and the engine seriel number. have them look for bulliten number 2007-011.
may also take a call to yamaha tech RTA.
your pump arm number is wrong but your PID is just out of the recall range.
pump number should be 6D04.
pump is also back ordered and has been since march.
 
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