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I have twin 2001 150 HPDI. My starboard engine last year made a funny noise when slowing down and started a ticking noise at idle. I did not see anything unusal and it continued to run great thru March 06. Preparing it for the next season, I did the normal things, change plugs, change lower unit oil, check fuel pump belt etc.
Well a couple weekends ago, I fished in a tournament and idled the engine about most of the day. When we went to head home for the day, the starboard engine would not come up to full RPM, like the port engine. It acted like a plug or two was fouled, which I experienced last year and got resolve by you fine gentlemen. It eventualy cleared out and came up to normal RPM.
Someone suggested to me to check the compression on the engine. I followed Yamaha's procedure and for 5 out of the 6 cylinders was at 115 to 125 psi and 1-cylinder was at 90 to 92 psi. I also found the spark plug on the low pressure cylinder to be half fouled on one side of the plug. I am gathering that this is the one that fouled on the previous weekend.
The low pressure cylinder was at the bottom left when looking at the backside of the engine.
I do run Seafoam religiously and I use Amzoil. One thing, the port engine burns 2 to almost 3-times as much oil as the starboard. I have hooked up both engines to the computer and the starboard O2 sensor is stable, however the Port Engine O2 sensor drops down (in the parameters allowed) at extended idle, but picks up when the rpm is raised.
Any thoughts of what the problem is and how to best address it. It runs great at all rpms except for the low rpm knocking.
Thanks in advance for your help.
Scott
Well a couple weekends ago, I fished in a tournament and idled the engine about most of the day. When we went to head home for the day, the starboard engine would not come up to full RPM, like the port engine. It acted like a plug or two was fouled, which I experienced last year and got resolve by you fine gentlemen. It eventualy cleared out and came up to normal RPM.
Someone suggested to me to check the compression on the engine. I followed Yamaha's procedure and for 5 out of the 6 cylinders was at 115 to 125 psi and 1-cylinder was at 90 to 92 psi. I also found the spark plug on the low pressure cylinder to be half fouled on one side of the plug. I am gathering that this is the one that fouled on the previous weekend.
The low pressure cylinder was at the bottom left when looking at the backside of the engine.
I do run Seafoam religiously and I use Amzoil. One thing, the port engine burns 2 to almost 3-times as much oil as the starboard. I have hooked up both engines to the computer and the starboard O2 sensor is stable, however the Port Engine O2 sensor drops down (in the parameters allowed) at extended idle, but picks up when the rpm is raised.
Any thoughts of what the problem is and how to best address it. It runs great at all rpms except for the low rpm knocking.
Thanks in advance for your help.
Scott
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