99 Yamaha 150 hp will not pump water

[ermess]

99 yamaha 150 will not pump | Author: Ed Messbarger | Date: 6/30/2005 8:54:01 PM <br />Customer has replaced two water pumps in last 2 months and now has called me. Did diagnostics engine is still in good shape (120 psi on all cylinders) Thermostats have been removed. Boat is in water but will not pump. put hose on flush port with lower unit in water, engine temp. 115 degrees. remove hose and run engine and temp climbs 140 degrees and nothing out of tell tale. removed hose from water pressure valve, hooked up hose to flush port, started engine, no water pumped up to water pressure valve hose.<br />Could it be a third pump? or something else.

 

[rodbolt]

Re: 99 Yamaha 150 hp will not pump water

remove the geaar case<br /> attache the hose to the water tube. turn water on full . you should now have a tell tale. if not you most likly haave aa restriction in the power heaad aadapter. the pressure valve and t-stats must be in place for proper system operation. the water enters the exhaust cover chamber first. from there as the block fills the excess water pressure is bled off Via the relief valve and dumped into the exhaust housing. the tell tale water is taken from the same chamber. neither have anything to do with circulation through the block. if you have water flow when connected directly to the inlet tube then double check the pump. make sure the parts were assembled correctly and the rubber dam and holding bracket have been removed and cleaned. occasionally in the salt pond the corrosion will lift the dam and it will suck air on reassembly of the pump if not cleaned. also check the pump housing for any signs of melting.<br /> replace it if any signs of melt are presant.

 

[ermess]

Re: 99 Yamaha 150 hp will not pump water

After inspecting pump parts. I have noticed the metal insert tabs traveled past the plastic housing grooves. Would this be caused by running pump with out water, bent drive shaft, ??<br />The drive shaft does not look bent. If drive shaft was bent wouldn't oil seal below pump be affected?<br />Also There was a great deal of corrosion underneath the rubber dam, which had raised the rubber considerably.

 

[rodbolt]

Re: 99 Yamaha 150 hp will not pump water

moist likly an assembly error or it was run dry and melted the housing. the raised rubber dam will create all kinds of problems.<br /> if the drive shaft was bent that bad it would most likly have broken, or at least the insert cup would have worn some serious grooves in the shaft just below the top of the nylon housing. without seeing it I would assume the housing is trash if the insert cup lugs have rotaed from the sockets in the housing

 

[ermess]

Re: 99 Yamaha 150 hp will not pump water

No groove on driveshaft. Is the Dam directinal? I assume the rounded edge is closest to the pump housing but on the straight edge does it tuck into the dam holder edge or does that straight edge lay on top of dam holder edge. I only ask because this pump has been apart so many times. And you just don,t know if the other tech got it right.<br />Thanks <br />Ed

 

[rodbolt]

Re: 99 Yamaha 150 hp will not pump water

I dont think it makes much difference. if you buy it new its symetrical. if I was looking at it I could tell. just make sure all the corrosion is gone.

 

[bigbrownbuku]

Re: 99 Yamaha 150 hp will not pump water

the parts fiche picture will make it clearer.<br />so will the yamaha service manual.

 

[ermess]

Re: 99 Yamaha 150 hp will not pump water

Water pump works great. This engine has some serious maintenance issues, - cables, fuel system, jackplate, and good sync & link<br />Thanks<br />Ed