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Low RPM under load at full throttle

patrscoe

Member III
Update
Short haul this past week.
Had the boat yard mechanic check the following:
-Straight shaft - good
FOF prop installed proper - Good
Motor mounts while under load - they were in good shape, no wobbling and moving no matter what load or rpm
Also note that the bottom had very little growth from the summer and the prop only had a few very tiny barnacles so overall it was a lot better than I thought I was going to see. I dive and clean my prop every 5 weeks.

So I removed the FOF prop and installed my 20 yr 2 blade fixed.
Vibration is gone and although my rpms were not where I would want them to be, they were around 2450 rpm and had about close to 6 kts.
I am optomistic that when I rebuild the fuel injection pump and new injectors, new lift pump and relocate my secondary filter to allow for a little better hose run, and go through my entire exhaust system this winter and clean / replace as needed, I will hopefully get another few hundred rpms.

Eventually Flexofold did respond to my concerns and said it should have worked... but I is clearly the FOF prop. They indicated they will take it back but needs to be in great condition... It's been on my sailboat?... I'll clean it up and send it back to them. See what happens.
 

patrscoe

Member III
Finished replacing my fuel injectors with new injectors and also replaced all the returned injector hoses and clamps.
Not a major difference but there is some. Smoother at idle. One I started to have RPM issues, my idle rpms dropped and I adjusted the set screw to +/-800 RPM and after injector replacement, it is just over 1000 which I also gain another 250 RPMs.

With the prop change back to my old 2 blade fixed and fuel injector replacement, I am up to about 2650 to 2700 rpms full load at cruising speed.
It has been extremely hot in Aug and no wind - which is the time barnacles thrives I believe there are some on my prop.

It ended up being multiple issues causing low rpms. Now I am trying to figure out what prop I should install (it has became a winter purchase and install). I have been in contact with West with a Campbell prop. but would rather find a folding or feathering prop (without the vibration).
 

frick

Member III
I will plan on removing the exhaust elbow and inspect. If that looks clear, I will move to the fuel injectors.

When I purchased the sailboat, late fall 2018 and the engine was surveyed in excellent condition. It ran at the proper RPMs.
Maybe this is a coincidence or not, late 2019 I got caught in a nasty storm for most of the day and it really tossed me around, and within the last 1/2 mile to the marina, my engine died. I knew something was wrong because I was losing RPMs and power; I restarted the engine within 20 minutes, and later in the fall of 2019 and into 2020, I corrected the issue by chasing down air leaks into the fuel system and clogged filters.
I continued to struggle with the issue again 2020 as I found another leak in the older hose (that short hose between the filter to the bleed valve) and it started hard.
So this winter I replaced everything from the tank to the bleed valve, and also cleaned the tank and replace the fuel. During 2020, fighting my air problem, it never got to the proper RPMs. Although I am not getting RPMs at load, the engine does not act like when I had air and clogged filters, as it starts up fine and does not stall.
So I am wondering if my injectors are dirty from the above but I would think that I would notice the engine not running right at lower RPMs and not starting well.
If you secondary paper fuel filter gets wet it can restrict the fuel flow rate. When you mentioned you got bounced around I thought ah, the motion of the ocean stirred up you fuel.
 
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