OX66 250 fuel consumption issue

[mand1204]

Running twin OX66 250's on my contender and I've notice the last several trips one is consuming more fuel than the other,8-9 gals. Motor has been running great when throttled up but at idle is rough. Any thoughts/ideas where to start?

[Sequoiha]

fouled plugs, o2 sensor, fuel filters, injectors, to name a few.

[boats.net]

Check diaphrams in LP fuel pumps to see if ruptured.

[mand1204]

Second trip on plugs but worth checking....filters are 6-7 months old they're cheap so I'll change out.....after that I'll work towards the other suggestion. Thanks for the help. Any others out there?

[99yam40]

you can easily monitor fuel pressures/vacuum to see if you have restrictions instead of just replacing filters.
Fuel LP pumps can be unbolted from motor and pump primer to see if it is leaking fuel out pulse port

O2 sensors maybe a little harder to check out along with the injectors

[jb123]

see any unspent fuel out of prop/sheen on water ??

[mand1204]

Went home yesterday and started by pulling plugs.....last to come out was fouled with 'blue emulsion'.....pulled the head and found the head gasket has been leaking into the cylinder.....checked the cylinder walls and everything looks good...new gasket and plugs today.....we'll see what happens....thanks to all for the insight and suggestions will update after test run
MA

[99yam40]

Check to make sure all of the surfaces are flat and in spec before putting back together