Problems with waterpump Vmax 150 TRP

Changed my impeller, cup, gaskets the other day. No problems with old stuff, just performing some preventative maint. Now I can't get water out, unless I gun the motor a couple of times. Talked to mechanic and he said to leave the spacers and wave washer out to keep the impeller a little higher in the cup. Bought a new kit and housing ( because I melted the other housing a tad) Changed everything again, and still cannot get water out until I gun it. Any tips?
2003 Yamaha VMAX TRP 150

[boats.net]

If housing is melted then it's not getting enough water to pump. Run in water and not on water hose, if you are running in water make sure lower unit is far enough below water line for pump to prime.

Should've mentioned all my attempts were tried in the water.
Not doing anything different than I have done in the past. Had it apart three times now and can't see anything wrong. I melted the housing( a small section under the cup) decided to change anyway since it was apart. Trying to keep from doing it again. Thanks

[boats.net]

I have never tried leaving washers out of water pump, but i would put them back in. Check the rubber water tube grommet in housing.

[Dennisg]

Hi, have you checked for a blockage of some kind in the water tube from the pump to the motor? I totally agree with Boats .Net, Put all the washers and what ever else Yamaha says to use. Your local mechinic is not a engineer. I doubt that he knows how better to put a water pump together than the people who designed it.
Dennis

Did you check to make sure that you put the impeller in correctly? I know it sounds like a stupid question but I have seen people bend the blades the wrong direction before.

[Operaman]

I have an 89 Excell (225). I also did a water pump complete housing kit change out. After running at idle for a while, it stops pumping enough pressure to cool. I have to put in nuetral, rev to 1400-1500 and then it starts pumping better again. You can hear the pitch of the exhaust change, then the water starts spitting out of the exhaust holes under the power head. It does come out of the water indicator tube at all times. Thermostats were also changed out.
A mechanic across the canal asked how it was going, I explained my symptoms and he stated he has had 6 do the same thing. We have come to the conclusion that the mold for the impeller must be off just a bit. The pumps were all purchased on Long Island, different vendors.

Anybody else experiencing this?

I checked the impeller and it is in correctly, I am replacing the water seal on the water pump housing and the one inside upper unit around water pipe.
When I get it to pickup it is a very hard stream out the telltale hole.
I have a low water pickup, so I should'nt have to submerge the whole lower unit.
Do I need to use any kind of sealant on the water pump housing or just trust the o-ring?
I also re-installed the washers on top of the impeller.
I'll get back when I try it on the water again, should be within a day or two.
Don't like having to look back everytime I start to make sure it's pissin', I do like to fish in the dark.
Thanks for the replies.

[boats.net]

Even with low water pickup you do have to submerge lower unit, the water pump is not self priming and has to be under water to prime on start up. You can use sealant to hold water pump o ring in place.

Allright guys, figured it out.
Put the cup inside the housing and the impeller inside the cup, noticed about an 1/8" gap from the bottom of the cup to impeller. Also noticed when I set the housing on a flat surface it had a gap in the center of about .020". I spread JB weld around the sides of the cup and installed in housing. After that cured I put the housing on a table top belt sander and sanded til the impeller had about only a 1/16" clearance inside the cup. No problems with the o-ring. Put a little silcone on it to hold in place. I think the o-ring is now where it should be. About half way in the groove.
Put just the low water pickup in the water and after starting it is pumping within 3-5 seconds with alot better pressure.

you need to change the housing any time a housing shows signs that it got hot (plastic melted) it needs to be changed to a new one I would put a new wp kit and housing in put some grease in housing to hold oring put cup in then put oring around cup add grease put on, also put washers and collar back on impellar and make sure gear case is submerged and water is above cavitation plate

Thanks but you might want to go back and reread a little slower.
I installed a whole new kit, housing and all. It is with the new kit that I had the problems. Housing out of the box had over a .020" gap in the center, doesn't matter how tight you get the bolts on the four corners, if the center isn't touching. Factory flaw that needs to be fixed.
Ive' been to three different mechanics who said "deal with it". I am not satisfied with that. I could be in 6" of water, start, and not have to worry about it pissin'. As long as I had the low water pickup was in the water it worked.
Put all new stuff on and mechanics say its just something you have to live with. "Jack the motor all the way down, tuck it up under the boat and gun it a few times in reverse," what a joke.
Most of the time where I fish you can't get the cavitation plate under water.
Not rippin' on you, just makes me mad when a certified Yamaha mechanic who supposedly does 10 a week says "deal with it, that's how them Yamahas are".
I handled it, and I hope it helps some other DIY's out.

Well not rippin on you,but if the impellar isnt below water line it will cavitate and over heat warping the housing most of the flats boats guys come in all the time like that all it takes is aboust 15 sec. of cavitating ,warped housing,when muffs are put on most of the time they are old and dont seal very well not letting enough water to the pump the best way to start it is put it in a 55 gal drum or a garbage can cut in half ,most good mechanic wont tell you to live with it,they will find the answer to fix it