Failed impeller change?

[cmichener]

I changed the impeller on my 2000 Johnson outboard. The pee stream wasn't great after completing the job and it gradually got worse. I took the lower unit off to inspect but couldn't find any issues. I took the impeller out. It seemed fine so I put it back into place and made sure the key activated. After reassembling, the outboard had a very strong pee stream. The strong pee stream continued yesterday when I put my boat to use. I had an issue with my motor not wanting to run at low RPM yesterday so I put it on the muffs today. Unbelievably, the pee stream diminished once again. The water pump is definitely not doing what it's supposed to. Any ideas about what could be causing my issue as I mentally prepare to drop the lower unit for the 3rd time? I did notice a bit of pitting on the casing of the lower unit where the gasket that goes below the impeller cup would go.

 

[CarMech1969]

So you bought an impeller only? Or a complete water pump kit??

 

[kbait]

Can’t test pump function with muffs. If it works in water, you’re good.

 

[F_R]

You cannot test a water pump by running on muffs. It is not pumping when you're doing that. Just allowing hose water to pass through

 

[cmichener]

I changed the whole kit. Why the change in pressure while using muffs? Before I had to change the impeller, the stream would put a hole in the ground because of the pressure. It was pushing water out like that after the second change, but now it is barely coming out. It gradually got worse today on the muffs. The water coming out was hot. I could actually see steam as it hit the ground. The overheat warning siren went off after my first attempt at replacing the impeller a couple weeks ago. It did not go off today, but I bet it was close. If it isn't the impeller, what else should I check? Thanks for the help!

 

[iggyw1]

All I can suggest is to be sure that your pick up tube is in the impeller housing correctly. Sometimes that is not placed properly, and it misses the rubber grommet in the impeller housing.

 

[cmichener]

I'll give it a look. I just ran it again to see if it would be any different after cooling down. Now there's no stream whatsoever.

 

[ThomW]

When you run an outboard on muffs there is no back pressure like when it is submerged in a bucket or the lake.

 

[iggyw1]

Might want to remove the thermostat to see if that may be the problem as well. Remove it (leave the cover off) and see if you get water flowing out of the thermostat housing. Cover wiring and the motor below the out flow of water so you do not fry things or short them out. If water does come out of motor, change your stat.

Question. When you changed the impeller, was the old impeller all in one piece or were there some small pieces missing?

 

[racerone]

What motor ?---Model # ???-----On many motors the tell tale water does NOT go through the block.----So if the tell tale stream is hot it may indicate a blockage.

 

[cmichener]

Thanks everyone. Iggy got it. Grommet issue (it wasn't in there). Feeling pretty smart right about now. I'd say all is well, but still have a couple of things to deal with. The motor chokes itself out after 10 minutes of running when using the fuel system in the boat. It runs fine on a separate tank. The guy at the shop told me the primer bulb was bad. I'm having a hard time believing that because it's my 3rd bulb this year. Finally went to the OEM on the 3rd try. Sometimes I'm able to prime the system with no problem. Other times I'm pumping for quite awhile before it takes. It pumped up firm right away today but still died after 10 minutes. There's a noticeable audible change in the way the motor runs when I trim it up and then back down. I'm wondering if the issue is more likely to be in the gas line and/or fuel pickup in the tank than the primer bulb. Thoughts?

 

[iggyw1]

First of all, the rubber ball on the fuel line is suppose to get firm while pumping it prior to starting your motor. Once the motor starts, the fuel pump is suppose to take over, and if the ball gets soft, there should be no problem with that. If you are having a problem at times pumping the ball firm, you have a plugged line, filter OR air vent on that tank in the boat.

When you use the portable gas tank, I am assuming that you are using a different fuel line on that tank of gas. When running your motor on the inboard fuel tank, just as it starts to die on you, pump the primer ball until it gets firm before the motor dies. That will allow the ball to put gas into the carb bowl. If the motor keeps running instead of dying out on you when you do this, you have a fuel pump problem. If the ball will not get firm, check the fuel line, the tank end filter and the air vent on the gas tank. This has no cost to trouble shoot these things.

NOTE: * If your motor runs fine on a portable tank with a different fuel line than your inboard tank, it is not the fuel pump but the fuel line or the filter at the tank end of that fuel line that is plugged up, or the air vent on the tank could be plugged.

Clean or change that filter if you can get to it. If you cannot, you can "back wash" the fuel line with an air compressor to clean that filter and fuel line, however, be aware, this could ruin the filter completely and/or put gunk back into your fuel tank, in which event, you could add an extra in-line filter before the fuel gets into your motor. (If it were my motor, I would use the compressor suggestion as a last resort). You can "backwash" the fuel tank air vent with the compressor too.