p4j

I have a Honda BF50D 4 stroke that when first started on the water the engine will not give more than 4000rpm and boat will not plane. If I then switch off the motor and restart the engine will rev to 5000rpm. what is causing this? Help

Hi p4j,

First off, you might want to change your post header to get more responses. Something like:
"BF50D Doesn't Reach Full RPM"
Because, I almost deleted it without opening it when I saw just your username with emoji. There are always hack attempts and people trying to illegitimately market stuff here so I don't usually open posts that look "funny" to me.

I'm not the resident 50 hp expert but I thought that I would suggest a couple of basic things that might get you started trying to figure this out.

If possible try using a different remote tank with clean, fresh fuel in it to see if things impove.

If that fails...

Try siphoning a pint fuel FROM THE BOTTOM OF THE TANK into a clear container and then let it sit for 30 minutes. See if any separation occurs.

If you have a water separator, you might want to drain/clean/service it and see if anything changes.

If you haven't replaced the fuel filters recently you may consider trying that.

Drain your VST into a clear container and see what comes out. Again, let the contents sit awhile and look for separation and/or debris or "gunk".

I offer these suggestions because these engines want/need clean, fresh fuel. Water in fuel can cause the engine to do unusual things. Water will "settle" out and sit below gasoline. It's bad because fuel is always drawn from the very bottom of the tank.

In this case, what could be happening is that a bit of water is being fed to the engine at startup after the boat sits. But after you run it and get the fuel moving and sloshing around, the water mixes back in and the engine runs better.

Of course, I am guessing about this as the cause but I have seen water in fuel cause wierd symptoms. Also, doing/checking these items is really a part of routine preventative maintenance so it's not a waste of your time to eliminate them as possibilities.

hopefully others here will offer some other things to check.

Good luck.

thanks for the info and shall look at the VST, although I have a feeling that the computer I is limiting the rpm for some reason and that is what I would like to find out.