After taking the advice of those who answered my original post, Buck Harrison and Pat McCartin I replaced the fuel filters and revved her up again, only to get 2200 rpms. I attached my gps chart plotter and headed out to give her a run, I looked down at the tachometer and it was registering -0- rpms and increased the speed throttle and got zilch, after about 10 minutes of decreasing and increasing the throttle it began to register 1000 rpms as I got speed up to 7.5 mph (according to gps,) I don't have a taffrail or speed indicator on board, it later registered 2200 rpms and I deduced it had to be corrosion on the terminal of the tachometer or a bad sending unit to the tach, any responsed out there? Thanks to everyone. Guy Proctor
Lost RPM's mystery solved today
- Thread starter NagMeKnot
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Sounds like you've got it. Check the sending unit
at the rear of the head. It is mounted so as to receive a signal (Hall effect) from the teeth of the flywheel. Usually it's just a poor connection of the spade connector to the sending unit. Depending on engine access, it is an easy fix. P.S. Guy, this is assuming you have a Yanmar in your 84 H31.
at the rear of the head. It is mounted so as to receive a signal (Hall effect) from the teeth of the flywheel. Usually it's just a poor connection of the spade connector to the sending unit. Depending on engine access, it is an easy fix. P.S. Guy, this is assuming you have a Yanmar in your 84 H31.
Guy,
I agree w/ Fred; you may have a poor connection at the sender unit. I also had (and to some extent still have) that problem on my Yanmar 4JH2. My RPM was erratic and would not go above about 2200. Cleaned connection at sender (after calling Norton Yacht service guys to find out where it is) and have had a marked improvement. I still don't think that its exactly accurate, but I can live w/ it.
I agree w/ Fred; you may have a poor connection at the sender unit. I also had (and to some extent still have) that problem on my Yanmar 4JH2. My RPM was erratic and would not go above about 2200. Cleaned connection at sender (after calling Norton Yacht service guys to find out where it is) and have had a marked improvement. I still don't think that its exactly accurate, but I can live w/ it.
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