2003 yamaha 250 fuel injected bogging down.

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
I took the boat out to the ocean today for a little fishing trip.i noticed that when its wide open the rpms go to 5200 max.after it runs there for about 20-30 seconds the tach starts dropping down to 4400 and seems to stay.if i pull back on throttle for a minute or 2 it will pull back up to 5100 and start the same process over again.sounds like it needs more fuel on the upper rpm range.i replaced the filter on the motor before leaving and it looked fairly clean inside the jar.i am goint to check the fitting on the tank and hoses leading to the water separator.supposedlt the injectors were cleaned and high pressure pump replaced last year. But i have no proof.just a say so.starts and runs excellant other than that.any help appreciated.
 
Joined
Jul 14, 2018
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Xltier, I have the same problem on my 2003 115 four stroke. Took it out and it will only run 3400 rpm. I can quickly throttle back and forward again and it will climb up to about 4400 and then settle back down to 3400. My primary fuel filter is new. Acts like it is starving for fuel on top end.
 

99yam40

Fleet Admiral
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Sep 7, 2008
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9,102
both of you need to monitor fuel pressur while the problem happens to make sure it stays in spec
 

xltier

Chief Petty Officer
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May 20, 2004
Messages
636
I would love to no how to do that.,i have a complete auto repair shop.is there a test port.i also noticed on the high pressure pump parts breakdown that there is a filter at the bottom of the reservoir.
 

99yam40

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Sep 7, 2008
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9,102
yes there is a filter in the VST and usually other places also.
if the fuel pressure is not the problem then no need to change the filters unless you just want to.
I am sure there is a test port on the rail somewhere.
service manual should have that type of info for testing
I do not have a motor like that so I do not have a manual
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
I took the vst apart today and going to replace the filter anyway.i have ordered a factory manual to find pressure specs.(I hope it says).also wondering about any other filters in line or in fuel injectors.maybe should also check the pickup tube fitting.water separator is new.there was no crap in the vst tank either.how about the feeder pumps not keeping up with high pressure pump requirements?? hard to imagine that thou.
 
Joined
Jul 14, 2018
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I took off my VST, the filter was only about 20% clogged, not too bad. I checked the high pressure pump in the VST also. Didn't do a pressure check just a check to make sure it was pumping. I also removed the injectors and sent them off to the Fuel Injector Man to get rebuilt. It was 85.00 plus shipping for the four injectors. He turned them around in one day. Put it all back together today and took it and ran it Problem solved. All four injectors had poor feed with two very poor according to the report he sent back with the injectors.
 

99yam40

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Sep 7, 2008
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9,102
thanks for coming back on line to let us know what fixed it.
lots of people do not do that

but it is good to know if the pressure is in spec before sending injectors off to be serviced
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
I took off my VST, the filter was only about 20% clogged, not too bad. I checked the high pressure pump in the VST also. Didn't do a pressure check just a check to make sure it was pumping. I also removed the injectors and sent them off to the Fuel Injector Man to get rebuilt. It was 85.00 plus shipping for the four injectors. He turned them around in one day. Put it all back together today and took it and ran it Problem solved. All four injectors had poor feed with two very poor according to the report he sent back with the injectors.

where did u send your injectors to be cleaned?
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
heavy dose of seafoam and a gallon of gas on a portable gas tank and run it thru.after it sat for 30 minutes or so I started it up and once all the smoke cleared it ran fine. so I guess it was dirty injectors`.this weekend will tell for sure.
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
LEFT ME STRANDED.Got towed this time.was going 5200 rpm ,stopped to look at a area and when I went to go again,it would not rev up past 1800.rpm.3 hours later it was back home and reving just fine.
 
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