OX66 Sudden increase in oil and fuel consumption

"I am running twin OX66 250HP

"I am running twin OX66 250HP (1999) motors. I've only had this boat for a few weeks. On the first trip, it appeared that the starboard engine used more oil than the port. I wasn't positive, thought maybe tank wasn't full to start. Second trip, oil consumption was even. Last trip, starboard engine used about 60% more than port. Overall fuel consumption also appeared very high, but probably matches the total oil consumption. Starboard engine seemed to be loosing top-end rpms at times.

I seem to remember having this problem on my old 2001 OX66 once. I think replacing the three low pressure fuel pumps is what fixed it. Maintenence records for new motors show starboard had fuel pumps replaced in 2007, so it seems weird that the starboard engine should be acting-up.

I did not notice any excessive smoke, odor, or idle problems. Compression is 105-110 on all cylinders. Any thoughts? Fuel pumps, or something else. I have already ordered three new pumps,and will take apart old ones to look for problems.

Might it be something else?"

vst

vst

"JUST-IN-TIME:

From reading

"JUST-IN-TIME:

From reading some of your other posts, I assume you mean to clean the tank and the filter therein. I do have the manual, but it is unclear as to the best procedure. It says I should choose whether to remove the tank as an assembly (with the throttle body), or take it apart while still on the motor (depending on what service is needed). For cleaning and filter, what is the easiest method? Just drop the bowl? What parts do I need to order - I'd like to have them before starting. I am a pretty good mechanic, once I know what to do. Thanks."

"what i do on the vst tank is

"what i do on the vst tank is ez

use phillps screw driver to loosen up the 10 screws
then take it off the motor
i un plug the sensor on it then unbolt the sensor
this way you can pull the vst tank out more
looses all the screws
remove the tank
if it is dirty clean it
replace filter
put all back together
before starting, you must prime the engine with the fuel bulbs"

"VST was CLEAN!!! I mean real

"VST was CLEAN!!! I mean really CLEAN! I tested LP pumps by loosening 2 mounting bolts and pumping bulb. No leaks out back hole. O2 sensor looked very clean, and tested OK (per manual).

Then, I checked the plugs and found severe fouling on lower starboard cylinder. Looked like salt deposits, and I assumed it was water intrusion. I pulled the head.The cylinder & piston top look great. Some evidence of superficial surface rust in places, but no actual water. I could not find any clear signs that the head gasket was leaking. There is NO water anywhere in the fuel system. All three filters are clean & dry. Compression is good, and was good right before this happened. Oil pump linkage was slightly rich.

Loosing a cylinder due to fouling explains low rpms. I assume high oil (& fuel) consumption is high due to higher throttle position used to compensate, combined with oil linkage adjustment.

I'm going to put it back together, but I'm still not sure what caused this. I have seen plugs fouled by salt water before (on other motors), and I am 99% sure this is what I'm lookng at.

On the bright side, all head bolts came out clean & easy (not like my old Johnsons!).

Any thoughts on other things to check?"

"u could have water in the oil

"u could have water in the oil also
look for that

trust me going through all of this, next year vst clean again

what oil r u running?"

"Water in the oil - that's

"Water in the oil - that's a good idea, I will check; however, that should also show-up in the vst, and not be limited to one cylinder.

I'll see if the new head gasket works. It would have been reassuring to see obvious signs of leakage.

New boat to me. Previous owner used Yamaha oil. I've been using oil from WalMart (Super Tech, I think). I've heard all the oil arguments before, but I've run it in quite a few different motors for many years with zero problems (Yamaha & Evinrude outboards, Jet Skis, and high-performance dirt bikes)."