what's the story behind the water pump impellor?

[mercerfisherman]

Hi, I have received a couple of suggestions on how to improve performance on my 84 Merc 50 hp... I have a problem where it seems like it's not getting enough gas when running at slow speed. I keep having to pump the primer bulb to get it fuel. In addition to checking fuel lines, gas tank, connections and primer bulb, people have suggested checking the fuel pump (which sounds logical) and looking at or replacing the waterpump impellor. I thought the impellor just helped keep the engine cool so it doesn't over heat. I get a steady stream of water out of the p-hole, so I can only assume the impellor is working fine. Any comments on how the impellor could possibly affect my "fuel" problem?

 

[gss036]

Re: what's the story behind the water pump impellor?

It doesn't, just cools the engine. I would suggest you rebuild the fuel pump if everything else checked out good. Put a little vaseoline petro jelly on the "O" rings on the fuel connections, that could help if you are sucking a little air. If you think you have a vaccum leak, spray a little bit of foamy shaing cream on the connection, it will get sucked right on in, don't over do it.
If the primer bulb is sucking down, open the vent. Hope this helps a little.

 

[tashasdaddy]

Re: what's the story behind the water pump impellor?

is this motor new to you or do you know or remember the last time it was change. if not change. they go out at the worst moment without warning..example i always start my 71 1350 with muffs just before leaving home. it's only 2 1/2 miles to the ramp everything fine in drive way, launch, 6 people on the dock, fire her up and no pee stream. back on the trailer, it was on the i know i need to do list, now it's on i have to do list. ruined a good day. could have been worse , we could have been out on the river at dusk, and thunder clouds closing in.
or i could have been running wot and not notice the pee stream quit, nothing wrong until it is a mass of metal.

 

[fishingdan]

Re: what's the story behind the water pump impellor?

You are right. The waterpump impeller has nothing to do with your fuel system. If the tell-tale is strong, you are probably fine with this.

You are either loosing prime or the fuel pumps are not working well.

The fuel pumps are located on each carb of your engine. If the carbs have never been serviced, that is probably something worth doing. This is commonly referred to as a carburator rebuild. The parts are cheap and it is easy to do.

Before doing that, I would take another close look at all of your fuel lines and your bulb. This will include from the fuel tank to the engine as well as the smaller fuel lines inside the engine cowling. The checkvalve in the bulbs can fail over time. It too is an easy replacement (<$15).

The classic merc 50 is a great engine. I have had one that I bought new in '85. It still runs great.

Dan