Yamaha ox66 issues

[striper56]

Changed the LP fuel pumps and took it for a hide. Same issue except it is now cutting out SOME of the time when pulling back the throttle from WOT down to 2400. I run it up to say 4000 + RPMS then pull the throttle back 10 times and it will only cut out once or twice. Injectors next?
Thanks

[fredbrad]

check your gas tank for a anti-siphon devices,sometimes are inside of the pickup tube similar to a little wire mesh (like on my case) or little steel ball inside the elbow fuel pickup

[Capt Terry]

I just replaced a Sierra filter with a Racor filter and vacuum gage on my '76 Seafari with an ETEC 150. On the first run I was at the BRP recommended limit of 4 in Hg. Bushwacker advised to look for an anti-siphon valve and remove it per ETEC ownersgroup recommendations to avoid running too lean & hot. Removed it and partially blocked screen on fuel tank vent. Have not rerun it yet, but fuel bulb is harder.

[afterhours]

Hey Striper56,

Just in case you don't have this link:

http://www.boatinfo.no/lib/yamaha/ma...003yamaha.html

Section 3 deals with fuel and there are some good write-ups on OX66 EFI engines. On 3-58 and 3-59 there is a discussion on CCS also. The engine only fires on 4 cylinders between 850 RPM and 2000 RPM and 5 cylinders below 850 RPM. There is also a shift cut switch that if actuated (for example by moving the throttle into neutral from WOT) causes the engine to drop two cylinders, no matter what the RPM's are. This is to avoid shock to the drive train.