# Yamaha Water Pump Modification



## texedd (Mar 25, 2008)

Does anyone know the exact procedures for the "shallow water modification" that certain dealers do for the crummy yammy WP (specifically Ronnies and Gulf Coast). I do all my own maintenance except for this...I tried once to true it up and did not enough or too little...I do know they mil down the housing, cup and have heard conflicting reports on either plugging or enlarging relief holes on the housing....I do my own filters, gear oil, thermostats, cooling flush, anything else, etc...tired of taking in for a watrer pump, which is easy to do...jsut dont know the mod procedure. Motor is a 2008 VMAX 200 HPDI SEries 2 on a Majek Illusion


----------



## ReefRaft (Feb 15, 2012)

I'm not sure of the specific problem your having, but on my SHO I could not build H2O at idle or run jacked up without getting hot. After talking to a marine mechanic I pulled the pump out. I removed .014" off the volute and put it back together. Now it pumps like crazy.


----------



## texedd (Mar 25, 2008)

what are you calling the volute? the housing? Problem is that you have to submerge the gear case to the pump and it is still slow to prime unless you do the mod...with the mod it works fine and pumps good pressure, without it, low pressure and have to jack all the way down on start up, which i told Yamaha kind of defeats the purpose of having low water pick ups on a high transomed, tunnel hulled boat.


----------



## bryanevans (Jun 24, 2011)

You need to install the older Johnson pump with key slot. I'm not at the shop, but will post the part number Monday. I have about 20 in stock.


----------



## FishAfrica (Jan 23, 2010)

Hey Bryan, can u install the Johnson pump on a late model 200 hpdi vmax?


----------



## bryanevans (Jun 24, 2011)

Yes, we do it all the time. You will have the best pressures you ever seen.


----------



## JDT4430 (Aug 8, 2010)

I might have to look into this also for my 225 Vmax. Aslways have to let the motor down as low as possiable to get it to prime.


----------



## InfamousJ (May 21, 2004)

ReefRaft said:


> I'm not sure of the specific problem your having, but on my SHO I could not build H2O at idle or run jacked up without getting hot. After talking to a marine mechanic I pulled the pump out. I removed .014" off the volute and put it back together. Now it pumps like crazy.


interesting.. have done no mods nor have any issues on my 225 sho... did your water pressure problems happen from the start of owning your sho or gradually came on as you used it? what model boat do you have it on?


----------



## texedd (Mar 25, 2008)

SHO and the motor I have VMAX series 2, have the same exact pump....any Yamaha with pick ups on the nose cone that are on a tunnel hulled boat have issues...mine didnt pump the first day i ran it...jacked all the way down, trimmed under....had problems until the pump was modified by service shops in my area (south texas). Bought the boat in Houston area and i kept tellign them about the mod, and they had no idea...its a south texas problem and a shallow water problem....there pump sucks compared to others


----------



## InfamousJ (May 21, 2004)

I've ran my 225 sho jacked up max 6" trimmed out running in 6"+ of water and had 15-20 psi. If it is all sho's, then I must have got lucky or my dealer knew how to correct the issue from the start of rigging my boat. My tunnel provides alot of water, cat hull.


----------



## Jetpadge (Mar 17, 2011)

InfamousJ said:


> I've ran my 225 sho jacked up max 6" trimmed out running in 6"+ of water and had 15-20 psi. If it is all sho's, then I must have got lucky or my dealer knew how to correct the issue from the start of rigging my boat. My tunnel provides alot of water, cat hull.


InfamousJ, what boat hull are you running your SHO on? I am having the same motor put on my new Ibis. I haven't heard of anyone having these issues.


----------



## theyallbreak (Jan 29, 2012)

bryanevans said:


> Yes, we do it all the time. You will have the best pressures you ever seen.


I guess I should have said something 10 years ago when my dad and I figured it out on the TRP it seems a lot of people have the problem. Hey do I get a cut on all the yamaha pump mods you do now. Lol


----------



## ShawnQ (May 21, 2004)

What is acceptable pressure at idle and at speed on these yamahas?


----------



## texedd (Mar 25, 2008)

theyallbreak.....i will give you a cut as long as it is less than labor at the shop! lol


----------



## FishAfrica (Jan 23, 2010)

bryanevans said:


> Yes, we do it all the time. You will have the best pressures you ever seen.


Great I will give you a call, thanks


----------



## ReefRaft (Feb 15, 2012)

Bernies boats does not do first crank on there SHO's until the mod to the H2O pump is done. This came from the mechanic that works there so there is an issue with the LWPU on th SHO. I also talk to Chris Mapp in POC and he is aware of the problems some of us our having. He told me he hasn't had enough time to figure it out. I mentioned the mod to the H2O pump and he agreed. After trimming the volute ( impeller housing) I can pump water at idle jacked all the way up and run the lenght of Shoalwater jacked up to 6 hauln *** and no temp alarm. So I think I got mine fixed with about 1.5 hrs of time invested.


----------



## finaddiction (Aug 8, 2005)

ReefRaft, how did you perform this water pump modification? Explanation of the procedure may help many of us. Thanks!

fin


----------



## bryanevans (Jun 24, 2011)

The OMC Impeller that replaces the Yamaha impeller is OMC # 389642, and Sierra # 18-3043. You have to use a dremel and saning stone to enlarge the diameter slightly, and a small file to enlarge the key slot. Pretty Easy, just takes a little patience.
This will work for 2 stroke 115,130,150,200,225,250, HPDI's 150,200,225,250,300's


----------



## InfamousJ (May 21, 2004)

Jetpadge said:


> InfamousJ, what boat hull are you running your SHO on? I am having the same motor put on my new Ibis. I haven't heard of anyone having these issues.





ReefRaft said:


> Bernies boats does not do first crank on there SHO's until the mod to the H2O pump is done. This came from the mechanic that works there so there is an issue with the LWPU on th SHO. I also talk to Chris Mapp in POC and he is aware of the problems some of us our having. He told me he hasn't had enough time to figure it out. I mentioned the mod to the H2O pump and he agreed. After trimming the volute ( impeller housing) I can pump water at idle jacked all the way up and run the lenght of Shoalwater jacked up to 6 hauln *** and no temp alarm. So I think I got mine fixed with about 1.5 hrs of time invested.


Jetpadge, I run a 22' Desperado Outlaw and ReefRaft answered my question. Bernie's Boats and Motors is who built my boat and rigged it as Dennis created the Desperado from scratch. I figured he'd be the one to make sure things are correct from the start and it sounds like he is on top of that issue from the start. I have had 0 issues so far on my rig. Great dealership and very knowledgable team there. Highly recommend them.


----------



## 2400tman (Jul 31, 2011)

Hey bryanevans , is this being covered under warranty?


----------



## bryanevans (Jun 24, 2011)

2400tman said:


> Hey bryanevans , is this being covered under warranty?


No, sorry Yamaha won't cover it.


----------



## ShawnQ (May 21, 2004)

bryanevans said:


> No, sorry Yamaha won't cover it.


Bryan, whats your cost to modify it?


----------



## bboswell (Aug 14, 2006)

I have not tried the OMC pump but I have done the following to my 150 V-Max

Sanded down the housing until the O-ring groove was nearly gone. This fixed having lower motor to prime and helped pressure a little

I then put some stretch in the pressure regulator spring which brought the pressure up even more. 

Even when hot I now hold nearly 5psi at idle and 15-20 when running jacked up to the top.


----------



## fito1411 (Jul 8, 2004)

Will the OMC impeller work on an SHO?


----------



## bryanevans (Jun 24, 2011)

Yes it will, same part numbers for the SHO


----------



## bryanevans (Jun 24, 2011)

I forgot we did one on a 250 SHO about 2 months ago.


----------



## fito1411 (Jul 8, 2004)

Thanks Bryan,
So that I understand you correctly. You Use a Dremmel and some sand paper to make the impeller fit in the housing correctly? and a file for the key slot?


----------



## bryanevans (Jun 24, 2011)

No grind down tho inside of the impeller to fit the drive shaft diameter, don't sand the cup down


----------



## finaddiction (Aug 8, 2005)

Bryan, thanks for the info on modifying the OMC impeller. Why does the OMC impeller pump more water than the Yamaha?

fin


----------



## bboswell (Aug 14, 2006)

finaddiction said:


> Bryan, thanks for the info on modifying the OMC impeller. Why does the OMC impeller pump more water than the Yamaha?
> 
> fin


I just ordered the impeller so I believe but I have the same question as above.

They don't appear to be designed much different.


----------



## bryanevans (Jun 24, 2011)

It is thicker rubber and slightly larger. You will see when your trying to put the cup back on how much tougher it is. This makes it sit tighter against the cup and makes better draw of water.


----------



## longboat (Apr 14, 2008)

Bryan,
Do you have a similar mod for Merc motors? I've a 115 4-stroke (2011) that seems to pump well with a new impeller, but as the impeller ages a couple months, it won't prime at idle. I have to rev it up to 1500-2000rpm to get the water pumping, and start planning another impeller change...


----------



## bryanevans (Jun 24, 2011)

longboat said:


> Bryan,
> Do you have a similar mod for Merc motors? I've a 115 4-stroke (2011) that seems to pump well with a new impeller, but as the impeller ages a couple months, it won't prime at idle. I have to rev it up to 1500-2000rpm to get the water pumping, and start planning another impeller change...


not currently that I am aware of. Mercs take longer to pick up, unless you change to 143 deg. T-Stats. This may help your issue.


----------



## longboat (Apr 14, 2008)

bryanevans said:


> not currently that I am aware of. Mercs take longer to pick up, unless you change to 143 deg. T-Stats. This may help your issue.


Thanks for the tip!


----------



## theyallbreak (Jan 29, 2012)

texedd said:


> theyallbreak.....i will give you a cut as long as it is less than labor at the shop! lol


I guess I should have made A kit with the sanding tool and impeller before I said something to people. Oh well I'm helping people out


----------



## finaddiction (Aug 8, 2005)

bryan, will this OMC impeller fit a 2003 Yamaha 225 4-stroke?

fin


----------



## bryanevans (Jun 24, 2011)

yes it will, still have to modify


----------



## finaddiction (Aug 8, 2005)

bryan, picked up a Sierra 18-3043 impeller (for a 1998 Yamaha c115) and layed it down flat beside a Yamaha one and the Sierra one is considerably taller. I measured the depth of the metal cup insert that goes into the housing and the impeller is ever so slightly taller than the cup is deep. Question is - will the bolts tighten down far enough, without distorting the housing, to allow the o-ring to make a good seal with no water leaking? It just seems extremely tight. Does this tight fit cause excessive wearing of the impeller or other water pump components?

I guess this taller impeller does not allow any water to "blow" around the impeller. Once that water is sucked in, it has no where to go except up the water tube. Others on this thread have mentioned grinding/sanding down the housing instead of using the OMC/Sierra impeller. I can now see how both would have similar results.

fin


----------



## bryanevans (Jun 24, 2011)

Yes it should have no problem tighting down. I have not had any issues, except great pressures.


----------



## Trouthunter (Dec 18, 1998)

Man that is some great information Bryan...thank you.

TH


----------



## finaddiction (Aug 8, 2005)

Yes bryan, I really appreciate the info that you have provided. Sending some greenies your way.

fin


----------



## bryanevans (Jun 24, 2011)

Glad it worked for you.


----------



## finaddiction (Aug 8, 2005)

Can't say its worked yet. I modified the new Sierra impeller and pulled the lower unit. I will install the new impeller tomorrow and see what kind of pressure I get. It had decent pressure before but sometimes the overheat alarm would sound when I jacked the motor up. I am hoping that this modification will remedy that.

fin


----------



## fishfeeder (Jan 29, 2009)

*'07 Yammi 90*

Bryan, I think this horse has one more ride in it so here goes. Is there a similar water pressure fix for the '07 Yammi 90? Mine has ZERO psi at idle and bounces off of zero with the jack at about 4 1/2 @4-4500 rpm. I sure don't like it.
p.s.- it is on a tunnel hull


----------



## bryanevans (Jun 24, 2011)

fishfeeder said:


> Bryan, I think this horse has one more ride in it so here goes. Is there a similar water pressure fix for the '07 Yammi 90? Mine has ZERO psi at idle and bounces off of zero with the jack at about 4 1/2 @4-4500 rpm. I sure don't like it.
> p.s.- it is on a tunnel hull


not to my knowledge, sorry


----------



## Salt Water Texan (Oct 1, 2009)

Does anyone know a mechanic in the Corpus Christi area who can do this modification ?


----------



## FishAfrica (Jan 23, 2010)

I bought a modified pump from Bryan at Evans Marine, he shipped it and I got it the next day. I installed it and then ran it for 3 hours, it appears to have gained me 3-5psi water pressure compared to the non modified pump. More testing upcoming, but so far im pleased- thanks Bryan


----------



## theyallbreak (Jan 29, 2012)

QUOTE=FishAfrica;4358100]I bought a modified pump from Bryan at Evans Marine, he shipped it and I got it the next day. I installed it and then ran it for 3 hours, it appears to have gained me 3-5psi water pressure compared to the non modified pump. More testing upcoming, but so far im pleased- thanks Bryan[/QUOTE]

That's funny right there a modified pump. Lol is that what you call a sanding wheel and a omc impeller.


----------



## FishAfrica (Jan 23, 2010)

theyallbreak said:


> QUOTE=FishAfrica;4358100]I bought a modified pump from Bryan at Evans Marine, he shipped it and I got it the next day. I installed it and then ran it for 3 hours, it appears to have gained me 3-5psi water pressure compared to the non modified pump. More testing upcoming, but so far im pleased- thanks Bryan


That's funny right there a modified pump. Lol is that what you call a sanding wheel and a omc impeller.[/QUOTE]

Yep thats what I'd call it, the impeller is inside the pump right?
Not sure what your beef is, I don't know you........


----------



## bryanevans (Jun 24, 2011)

theyallbreak said:


> QUOTE=FishAfrica;4358100]I bought a modified pump from Bryan at Evans Marine, he shipped it and I got it the next day. I installed it and then ran it for 3 hours, it appears to have gained me 3-5psi water pressure compared to the non modified pump. More testing upcoming, but so far im pleased- thanks Bryan


That's funny right there a modified pump. Lol is that what you call a sanding wheel and a omc impeller.[/QUOTE]
The credit is due to his father, They are the one's who came up with the modification. I just pass it on to help out. I sell the impeller modified for 60.00, the OMC Impeller is 45.00, and I make 15.00 modifying it so guys can slip it on. I have never taken credit for this Jason, and have always told people you and your father came up with the impeller modification. I don't know why you are so upset? If it makes you feel better, I will send them to you, and you can do the modification, It's not like I'm making much on it.


----------



## ReelWork (May 21, 2004)

Jiffy pop on the stove..


----------



## patwilson (Jan 13, 2006)

Lots of butter please...


----------



## FishAfrica (Jan 23, 2010)

Ok that explains it, thanks for clearing it up Bryan.


----------

