Thread: Water pump issue

With the motor running and in the water (or muffs on) run a piece of weed wacker line up the hose. If you don't do it this way all you will do is push whatever is in there up further.

Sounds to me like the "Inlet strainer to the compressor".
The inlet screen is found on the port side of the power head and needs to be removed and cleaned along with hooking the motor up to the flush port and back flushing the motor to remove all the sediment that is trapped in the lower block.

Unfortunately, most service centers do not know and or understand that this "Should" be part of the maintenance cycle when changing an impeller! They "assume" that a high heat indicator means a faulty or weak impeller, they change it out only to find the same issue. The problem is the inlet water is sucked through a screen prior to entering the compressor. This screen gets clogged and, as a result, you get high heat due to lack of water pressure entering the compressor. A friend of mine learned this the hard way. Changed impeller, boat in water, boat out of water numberous times only to find the fix was less than 5 minutes!

To my knowledge, Mercury is the only one using this inlet strainer or filter and there have been numberous issues as a result. The most common is the high heat indicator alarm sounding at low RPM that sends the motor to limp mode. If, out of the hole, you go max throttle, no alarm because the motor gets enough water when it is up on RPM's.

If it isn't peeing water, there could be a number of things. Are you getting a high heat alarm (or any alarm)? If not, then more than likely you have a blockage. Not peeing could be an indication of a weak impeller, bad compressor, plugged pee hole, plugged inlet screen.

Try finding and cleaning the screen first. The run the flush port on the side of the motor just to flush everything. Hook up the muffs and see if it works. If not, take your water hose and find a screw on small enough to shoot a small stream that will fit in to the pee hole and reverse flush it by shooting water up into it. This has worked for me when everything else has failed.

How long did you let it run, mine must run till it system loads up the it starts to pee. If your is an older one you might want to take in and have a prostrate exam and see if anything else is going on. ��

Thanks for the suggestions. Yes, we let it run. Even got on plane for a short distance.

I had the same problem on a 50 hp Merc. I tried running a wire up the telltale ( Pee hole) and it didn't fix the problem. I then followed the rubber hose from the back of the telltale to where it was connected to the engine block- about a foot or so of hose connects the two. I removed the hose from the telltale and the engine block and laid it in the pavement and whacked it with a hammer up and down its length. I then blew a bunch of debris out of it that had been clogging the hose. Hooked the hose back up and it started peeing like it was supposed to.

Originally Posted by goblerblaster

I had the same problem on a 50 hp Merc. I tried running a wire up the telltale ( Pee hole) and it didn't fix the problem. I then followed the rubber hose from the back of the telltale to where it was connected to the engine block- about a foot or so of hose connects the two. I removed the hose from the telltale and the engine block and laid it in the pavement and whacked it with a hammer up and down its length. I then blew a bunch of debris out of it that had been clogging the hose. Hooked the hose back up and it started peeing like it was supposed to.

Have heard dirtdobbers will plug up a pee line

Originally Posted by NIMROD

Have heard dirtdobbers will plug up a pee line

I've heard that, too, Nimrod .... but, I fail to see how they could get into such a small opening. Besides, they make their nests in overhangs and shady places, and the side of a outboard doesn't really fit the bill. IMHO
Now I have heard of them getting inside the cowl ... but even they'd have to have vent holes big enough for the wasp to get through.

Now, spiders ... that's another possibility !!

Originally Posted by CrappiePappy

I've heard that, too, Nimrod .... but, I fail to see how they could get into such a small opening. Besides, they make their nests in overhangs and shady places, and the side of a outboard doesn't really fit the bill. IMHO
Now I have heard of them getting inside the cowl ... but even they'd have to have vent holes big enough for the wasp to get through.

Now, spiders ... that's another possibility !!

They do when the outlet is raw hose for sure. About 6" up the line.






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