Replacing impeller. How often? Good Maintenance Manual?

[Dimitri-2000X-Tampa]

I was using the BF to mean Big Foot as mine is a Mercury. I have some shop manual but it has a really poor diagram of the cooling system, kind of generic even, pretty useless.

When I started my motor today, it seemed like it had a fairly decent pee pressure. Between about 1000 and 1500 RPM, the stream gets a little stronger but then doesn't get any stronger in higher RPM's. Once again when I took it out and sent the RPM's over 4000, the overheat sensor went off. Keeping RPM's down low made the overheat go off and it seemed like the flow was more dribbly than when I first started, still a fair amount of water coming out, but just not a high enough pressure for my liking. Hard to tell exactly how much pressure it should have. Definitely not as strong as when I first put the new impellor on and ran it using the rabbit ears.

Questions are why is the stream a bit weaker after the engine has been running for a while, and could salt/corrosion in my water jackets be contributing to this?

I was hoping to make a trip in a couple weeks and this is seriously threatening that. Another bunk (mid bunk this time) came loose on my trailer so I have to fix that before pulling it back out and trying a second rebuild on the pump.

Anybody ever put a good impellor in a worn pump housing and have this happen?

The other possibility I've been considering is maybe some sort of obstruction somewhere...which is hard to figure out without a good diagram. I did take the anodes out and spray salt-away in the holes. I wonder if its possible that a piece of salt broke off somewhere and clogged a passageway in the motor. Or that I picked up some sand. If the pee hole is just an indicator, then even if that is clogged up, there should still be plenty of cooling water and no alarms. The obstruction would have to be elsewhere...unfortunately, it still seems most likely that the water pump is somehow still hosed up.

[rowdy]

I just replaced the impellor after 10 years. The thing must have pumped tons of sand and doesn't look much worse for the wear. Really held-up over the years.

[Boblee]

Pull the hose off the pee hole outlet and check that is not blocked, that is the usual problem (wasps etc) but if it's overheating it sounds like something more.
The thermostat could also be blocked shut.

[marsanden]

the impeller is wery cheap ...the engine risks if it doesnt works perfectly are wery big.
so i change it every 3 years , as mercury recomends.

[argonaut]

Isn't the BF 50 a 50 HP?

No... sorry, not the same thing

Honda named their 5HP motor model BF50... not BF5 as you might have expected.
Thus when the 50HP model came along, the BF50 distinction was already used. So... what to do?
In a fit of marketing genius reminiscent of ¨new" coke, they dubbed the 50HP motor, the BF50A.

I think the A stands for ¨A Lot Bigger Than the 5.¨

The manual you saw is correct, and you have to pay attention in the generic Honda outboard books like Seloc because they sprinkle the 5HP info all over the place, sometimes on the same page as it´s big brother, the BF50A. If you don see an ¨A¨ it´s the little guy.

The factory Honda manuals I bought included all of the updates since they were printed to bring it up to present, I think they were worth the cost, though they are far from perfect.
An annoying nuisance with respect to the manuals is the complete absence of honda part numbers in any of the exploded diagrams, or maybe this is more Honda genius.
Contrast that with Suzuki, where complete service manuals including exploded mech and electrical diagrams and part numbers can be found online.

-argo, aka NHNT (No Honda Next Time)

http://www.honda-marine.com/owners/Owne ... oup=BF50hp