2000 honda 50 water pump impellor help

Nuaticocat

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Sep 1, 2012
Messages
27
I just changed the pump impellor on my 50 Honda again, third time this year. I ran the crap out of it last weekend in the bay. Ran great. Came home and flushed using earmuffs. Took it to the river and it had no water at the tell tale or on the guage. Changed the impellor and ran it in a trash can full of water. Tell tale ran fine for a few minutes then stopped.
I have noticed that the tell tale just dribbles at idle but runs ok at higher rpms. I am getting about 5 to 7 lbs on the guage at 4500 rpm. It seems like the pump impellor frys if I run on earmuffs , although there is a lot of water going to them. They are the rectangular kind with a feed on both sides. They cover the entire intake. This motors telltale seems kind of puny compared to my merc 75 or 25.
Anybody have any advice? Am I doing something wrong installing the impellor? They have all been Honda parts. I think the impellor is turning in the correct direction according to my cheapo manual. The motor never overheats unless the telltale stops, so I assume the block is getting enough water.

thanks
 

millacd

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Jul 8, 2013
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Re: 2000 honda 50 water pump impellor help

what do your impellers look like when you remove them?
 

millacd

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Joined
Jul 8, 2013
Messages
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Re: 2000 honda 50 water pump impellor help

My guess would be you are installing it with the blades in the wrong direction. although you said you checked in the manual... which way to the blades point when looking "up" into the impeller housing?

or maybe its the wrong impeller
 

MattFL

Master Chief Petty Officer
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Oct 20, 2010
Messages
827
Re: 2000 honda 50 water pump impellor help

Are you using an OEM impeller, or an aftermarket brand? Also what does the inside of your pump housing look like, is it smooth? I've got essentially the same motor (1999 50HP Honda), I bought it new in 1999 and have replaced impellers as regular maintenance, but so far never had one come apart, so you've got something not quite right somewhere. I would buy a whole new pump, OEM not aftermarket, and replace it all. If one of those pump parts gets shot up into the block and plugs up the plumbing then you're looking at a potentially much more involved fix. I always flush mine on muffs and it has never been a problem, just make sure you're getting enough water into the lower unit that its flowing back out the water vent that is above the prop, on the underside of the anti-ventilation plate.
 

Nuaticocat

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Sep 1, 2012
Messages
27
Re: 2000 honda 50 water pump impellor help

Thanks for the comments. The parts have all been Honda oem. Impellor is in correctly. I think my problem is my muffs not supplying enough water to cover the pump. Took it apart today. innards all good, all parts new down to the pump base. Cleaned the tube and flushed the block at the telltale nipple by taking it out and adapting a hose fitting down to it. Found my tee fitting going to the guage cracked and all the water going into the cover base. Reassembled with the hose just going to the telltale , motor in an elevated trashcan that covered water up to above the pump housing area. It spewed plenty of water out the telltale. I suspect that every time I fried a pump it was from running it on the muffs. Changed the oil since the dipstick tube was under water, just in case.
My mercs have always had plenty of water from those earmuffs, guess this Honda is a bit different.
 
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