Hi Bruce, I have a Yanmar 2GMF (~14HP) and have been perplexed by the same symptoms and perhaps the same issue (no load RPM is 3600, load caps around 2500-2800 forward, 3000 in reverse). It did not do this a prior to August or in years past I could get up to 3600 in forward gear with no issue. I am able to get up to about 3000 in reverse I would guess this is due to the physics of the prop. I noticed a small amount of variability on the high end when I was motoring for several hours. I've been trying to figure this out for about a month now.
I have got through a series of steps including advice given on the list here: 1. Replaced secondary fuel filter 2. Added a primary fuel filter (boat didn't have one originally). 3. Replace the entire exhaust elbow (the old one was a little rusty, but 99% clear of carbon (just finished this--what a pain the you know what). I had already replaced the air filter this summer so I know that was good, but checked that too. I also did my annual oil and coolant change. I'm left to believe it is an injector problem (note Don Casey says in his diesel repair guide this is the first thing to check). Hindsight being 20/20 I wish I had done this before the exhaust elbow as I believe it's easier to access on my 29-2, although I haven't taken them out yet. Everytime I think the next job will be easier Murphy comes out and laughs at me. Advice from one of the marinas was to add pure SeaFoam directly to the primary and secondary fuel filter and run the engine off of that, and also add a cetane booster. Yanmar recommends FPPF, but I couldn't find that so put in a 16 oz of Power Service Diesel Kleen + Cetane Boost. Now when I run the engine at the dock on full open throttle in forward gear I am getting a lot of black crude coming out of the exhaust. I believe this is coming from the injectors due to the Sea Foam and Power Service additive given the exhaust elbow is brand spanking new. Next week-end I will try running it for an extended period at FT and see what happens. My engine is also likely due to have the valves checked, but from what I've read this is likely not the issue based on the symptoms. Hopefully some of my experience helps you. Eugene Fodor "Hawk" 29-2
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
