Hollywood1053
Cadet
- Joined
- Jun 15, 2009
- Messages
- 13
It seems that Yamaha VMax's don't have good water pressure, especially at idle.
Mine registers 0 at idle and maybe 15 at 4000RPM.
I've seen the following recommended 'fix' on at least 2 occasions on other forums.
Does anyone have any first hand experience with this modification?
Seems too simple to be true...8-10lbs at idle??
"The fact that you are not getting any kind of water pressure (0) at idle tells me that the water pump is probably not priming and you are sucking air past the impeller housing. The 150 Yamaha VMAX in notorious for this problem. If you take your lower unit off, you will probably find that the plastic housing that contains the rubber impeller is warped which allows air to enter between the housing and the metal plate that it seats against. The result is no vacuum and no water pressure. Even a brand new plastic housing can be warped which is a manufacture defect(we found this to be true on a new one that I bought). To make this seat better against the metal plate and avoid sucking air, you have to take the housing and belt sand the top part of the housing to make it completely flat. Once this is done the housing will fit perfectly to the plate and now you will have good water pressure even at idle around 8 to 10 and at 4400 rpm it should be 20 or above."
Mine registers 0 at idle and maybe 15 at 4000RPM.
I've seen the following recommended 'fix' on at least 2 occasions on other forums.
Does anyone have any first hand experience with this modification?
Seems too simple to be true...8-10lbs at idle??
"The fact that you are not getting any kind of water pressure (0) at idle tells me that the water pump is probably not priming and you are sucking air past the impeller housing. The 150 Yamaha VMAX in notorious for this problem. If you take your lower unit off, you will probably find that the plastic housing that contains the rubber impeller is warped which allows air to enter between the housing and the metal plate that it seats against. The result is no vacuum and no water pressure. Even a brand new plastic housing can be warped which is a manufacture defect(we found this to be true on a new one that I bought). To make this seat better against the metal plate and avoid sucking air, you have to take the housing and belt sand the top part of the housing to make it completely flat. Once this is done the housing will fit perfectly to the plate and now you will have good water pressure even at idle around 8 to 10 and at 4400 rpm it should be 20 or above."