Loss of RPM

[Noah]

Did you dismiss or explore the injector suggestion?

[Jeff Tancock]

Talked to a local mechanic I know for a bit. He works on these engines quite a bit. He's too busy at this time of year to look at it any time soon.
He felt that the injectors couldn't be so bad that the engine would under perform in neutral. He gave me ideas on several things to check as I mentioned above.
I guess it's still a possibility though.
Thing is that the engine sounds smooth and seems to run well but it just tops out so early.
I'm planning on checking the RPMs too but it is still slow by at least a knot so that doesn't explain it.

[Noah]

Sorry, I am not a mechanic—just trying to learn along with you. Good luck.

[Ron Hill]

Jeff : You might read my Mainsheet Tech note article on rebuilding your injection pump. The rpm was great in neutral, but bled off when in gear!!
After checking all of the many other things (injectors, fuel pump, fuel lines, Racor etc.) I finally removed the injection pump and had it rebuilt.  That was the problem!!

A few thoughts

[Jeff Tancock]

Thanks Ron
I've just ordered the injectors. None in stock.
I'll try to locate your article although unlike you I have lost RPM in neutral as well.
Tomorrow I am going to go over all the fuel lines, vent etc and look for any place for air to get into the system.

[Jeff Tancock]

I'm hoping I ordered the right part nos.

70000-65209 for the injector and 17011-53620 for the gaskets...........

[Ron Hill]

Jeff : It has been written a number of times in the Mainsheet tech notes - take your injectors to a diesel place that services diesel trucks and have them rebuilt.  They will run a spray check and replace the tips etc.  It's half the price of new injectors!!!!!!

Injectors are NOT like sparkplugs and throw the old ones away, you rebuild them and carry them as spares!

A few thoughts

[Jeff Tancock]

Not here
$97 new and $60 to look at them and do what they need to. Also they are so backed up it would take a week to get to them.
I figured I might as well spring for new and keep trying things in the meantime.

[RV61]

Jeff,
I feel your pain and went thru this a few years ago. One old salt said start at the beginning and follow the fuel till the end. So I started with the fuel itself and took  sample off the bottom it was clean. Pulled fuel line pickup tube and found partially gummed up screen on end and tossed it and got very small improvement. Checked fuel vent hose and vent fitting on my stern found spiders partially blocking in the vent fitting as well as the fitting was upside down acting as a water collector thus why the separator kept getting the water out. Still not full RPM but again slight improvement. On to the water separator/ fuel filter changed filter no change on to the facet fuel pump found fuel was not pumping as fast as I thought it should pulled hose and pumped into a can to see this so OK checked lines and they were clear then ah what wrong with the pump and due to this forum found the mystery  filter in the Facet was fouled and cleaned it up a bingo that was the issue. Mine had a real fine mesh and cleaned it until all mesh was shiny silver. While I was at it did discover some not so tight hose clamps and some chafe and took care of those. Boat has run great since. On the hard starting issue mine would usually start but would have to stand on the glow plug button way too long so out came the glow plugs the tested fine by mechanic  cleaned up a little reinstalled and that solved that problem it almost start by looking at the start button after a 15 count on glow plug button. after reading all you have done and 2 symptoms of hard start and low RPMs did these both start to occur at the same time?  If so hope it is just a clogged fuel tank air vent line or fitting  if not I think you are on right path of injectors or injector pump. The best part was I learned the fuel system inside and out. Air flow in right places, no air in others and free flowing good fuel make happy engine. Good luck and let us know the outcome.       

[WTunnessen]

Last summer I replaced the injectors and had the fuel pump re-built by a diesel shop. Afterwards, I found I had more power than before. Prior to that, I had noticed what I thought was a slow loss of power over the prior few months before the engine began to stall out.  Your engine is the era as mine, although your engine hours will differ.  The diesel shop re-built my fuel pump in less than a week for a pretty reasonable cost. To pull the fuel pump, I followed the instructions on the message board and tech notes.

[lazybone]

Does anyone have the Kabota parts numbers for the injectors on a 25xp?

[Ron Hill]

Jeff : As Rick mentioned you need to confirm that you have removed the screen from the fuel pick up tube!!

A thought