2001 225 ox66

[kspringer]

I am about to pull what little hair i have left out. I have put a new O2 sensor in, cleaned and changed VST filter, regular fuel filter in bowel and put in new plugs. The motor runs great until it gets warm and then starts losing rpms at wot. After replacing all that stuff I have been fishing and running around lake, but for short runs and it did fine. I had a tournament this weekend and had to make at 24 mile run to my first spot and after running about 12 miles it started doing it again. I live around Ky lake and none of the mechanics seem to be able to diagnose the problem or even seem to care. I need some help. I did notice while running I was only getting about 14 psi of water pressure but no warning buzzers saying it was overheating. Could that have anything to do with it? Thanks for your help, I just dont know what to do. If I cant get this figured out Im just going to put on a new engine, but I was hoping to trade boats next spring and really dont want to do that right now

 

[yamamarinetech40]

Re: 2001 225 ox66

I don't think the water pressure has anything to do with your problem....nor do i think it's happening because engines are 'warm'.....I have to assume(and hate to do that) that your fuel system is clean, from the tank,thru filters....if the fuel system is indeed clean(you can take fuel sample from tank yourself in glass container)...then what you are describing is classic symptom of vacuum developing(above 5 inches of vacuum will starve engine)....would carefully check fuel tank vent, also check the safety check ball on fitting your fuel line attaches to on fuel tank...I have little use for these(just me personally) just due to fact that if my boat is upside down, I have other problems to worry about than leaking fuel...my boats seemed to lose this item somehow...it takes a while for the vacuum to develope as engine sucks fuel out of tank...you can purchase cheap(but works) vac gauge at any parts place...hook it into fuel system at engine with cowling off and have someone get a reading while running when problem starts happening(be careful)...also use some clear hose to connect and you'll need a barbed 'T' fitting and nipple fitting...clear hose will allow you to see if bubbles are present....good luck...

 

[rodbolt]

Re: 2001 225 ox66

the 3.1L motors are also hard on lift pumps. need to change them about every 3 years.
did they remove and clean/replace the injector filters as well?
do check lift pump intake vacum. 6" Hg is the maximum.
while your checking lift pump vacum also test fuel rail pressure.
must maintain 35 PSI at all times.

 

[kspringer]

Re: 2001 225 ox66

I just pulled 02 sensor cover off again and it had quite a bit of black oil inside black plastic cover. There was no oil inside barbell tube, 02 sensor or inside where 02 sensor screws in, but everything on outside looks like it has burnt oil on it. I still think this is where my problem is, what are your thoughts on this oil being present?

 

[rodbolt]

Re: 2001 225 ox66

either the gasket is leaking or the sensor threads are leaking.
can you get a clean shot of the block where the draw tube goes and the part number of the gasket kit you used.
do you know if the block ssy was EVER changed since about 2003?

 

[kspringer]

Re: 2001 225 ox66

I will try and get some shots today. If its leaking will that cause the loss of RPM's on top end?

 

[kspringer]

Re: 2001 225 ox66

how do I post pics? Would this cause rpm drops at wot?

 

[trailertrash20010]

Re: 2001 225 ox66

I have a 200 ox66 with the same problem,I just posted it on this site maybe to get some answers,if u find the cure please let me know,Thanks..

 

[99yam40]

Re: 2001 225 ox66

to post a picture hit reply and then go down to the
Additional Options page and then hit manage attachments
Locate the pic and upload
You may have to adjust the pic to get it the right size to send