I have a 40hp merc that is not pumping water out when running. The tube that runs out the back is clean. I dropped the lower unit to inspect the impeller and it looked fine. I went ahead and replace it with an impeller kit and kept the old one as a backup. I ran the hose up through the tube that the impeller housing connects to and it flowed out the piss tube fine so I figured that there is nothing clogged. I remounted the lower unit with the new impeller and I have the same problem. I start the engine and no water comes out. I ran it long enough to start getting the solid alarm which I think is for the over temp. Maybe someone can confirm this or correct me on it. What else could cause the water to not flow?
Having a similar issue, I took a drill on my 7.5(on the shaft with the lower unit off, sitting underwater) and spun it to check and make sure my pump was pumping ok ... not sure if that's an option on the 40...but sure did work on the 7.5 hehe made me glad I used a cordless hehe.
maybe try pump water from the bottom of the tube? maybe by putting your hose up in it you went past the problem? Don't know how far you had it up there but it sounds possible?
Everything went fine with the impeller on the lower unit.
At the same time while replacing the diaghram on my fuel pump I noticed that water from the lower unit runs into the engine block, exits on the port side of the block and travels through a flexible tube into the fuel pump which is on the starboard side. Through the fuel pump and exits to the tube that discharges the water on the starboard side.
Since I had the fuel pump out for the diaphram I examined the fuel pump area where the water flows and out to the tube on the starboard side. The fuel pump where the water flows was clogged with dirt. The engine had been sitting and some insects must have brought the dirt up. You couldn't see it, but you couldn't blow air through it.
Fixing it was simple, I used a piece of 12 gauge wire into one end of the fuel pump and out the other, dislodging the dirt. Would have never noticed this until I fired up the engine.
I put the hose right into the end of the tube that sits on the impeller housing. The water went through the engine and out the piss hole. I figured this must eliminate any threat of blockage but who knows. I may be missing something. I then checked the impeller and everything from there on down to the intake holes are clean. I have never seen this on other outboards before.
Is water getting into the pump housing? Something blocking the holes letting the water in.
I would think if water is getting in, then either the impeller is not turning, possibly caused by the key not seating into the impeller, or the metal housing must be spinning with the impeller.
When I replaced the metal cap in the housing there is a small slot that the metal housing sits in, perhaps that little tab is broken which would cause the housing to spin with the impeller.
You might have to go with an new pump housing, not just the impeller kit.
I've taken off the impeller again to inspect it and everything looks fine. It was still on the keyway fine and the housing is not slipping. I put the ear muffs on before removing the impeller and the water seems to come through the impeller pretty good. Not with alot of force by it does seep through. I do notice that alot of water also runs out a hole that is under the trim tab section. Is this hole suppose to be open? It's near the nut that you have to remove when lowering the lower unit. The nut that is located under the tril tab. I will try to get an adapter to mount a socket to my drill and see if I can spin it up with the ear muffs on and see if it pumps ok.
Well, with everything back together it still doesn't pee water. I noticed that when I am cranking the engine the water comes out in small stream as it use to do but when the engine fires up the water stops when it should be coming out even stronger. So it pumps a little when cranking but no running. Any suggestions?
someone mentioned this to me when i had a similar issue, sounds dumb, but is the gasket connecting the exhaust to the lower unit ok? also is the tube from the motor to the pump housing sealing properly?im sure someone on here can send you diagrams for your motor, to make sure you did everything right.
thanks everyone for your help. Finally figured it out. After the six time at checking the impeller I finally decided to look into the performance of the engine. It would run at idle fine but it did have some missing and it was stuborn to start. Found the plug wires reversed. My nephew must have been messing with the engine because he used it for awhile and it never did run good since I got it back.
But atleast it runs now. Hooray!
2001 40 hp mercury outboard cooling
Linear Mode
