250xb low water pressure

started having a problem with my 2003 250xb water pressure, it idles at 3psig when i first get to the lake but will only hold 10psig at wot, later on idle pressure is only about 1.5psig - wot still 10psig, the only way i can get pressure up is to drop jackplate 5'' below pad. i have installed new impeller, checked for any blockage,blew out gage tubing, changed gages, rebuilt popit valve---- nothing has helped---- looking for any more suggestions, also no alarm has gone off to show overheating THANKS

I'm in the same boat, mine has done it since i bought it 1 1/2 years ago. I have done the same as you, replaced everything with no difference in pressure. Then about two months ago i fired it up in the driveway and heard a clicking noise before it fired up and got water out the peehole in four seconds and the gauge read 4lb at idle and go to 15 when reved a little. Took it to the river and had 15 to 18 all day and idled at 4-5. Next trip out it was back to 1.5 at idle and 8-10 wot. Don, whats going on with these xb. Been running it 8-10 with no problems but dont like too.

First and foremost:

WOT water pressure specs DEPEND ON THE GEARCASE USED.

Models WITHOUT low water intakes in the nose of the case: 8-12 psi @ WOT.

Models WITH low water intakes in the nose of the case: 15+ Psi @ WOT.

On models WITH low water intakes, we commonly find this problem is caused by DEBRIS lodged between the LOW WATER INTAKES and the Water Pump. Usually requires removing the shift shaft bushing, any plates below the bushing and/or water pump, and VISUAL INSPECTION OF ALL PASSAGES. Commonly find chunks of wood floating around in here that can block the small passageways from the low water intakes (and essentially negate the added water supply from the low water pickups). http://www.bassboatcentral.com/smileys/wink.gif

There is no other accurate means of ensuring these passages are clear, other than "disassembly and inspection".

Don, I have low water intake in the nose, the debris you speak of, would this have not been seen by doing inspection when changing impeller ? This problem has just started in the past 2 months, motor has been running 15 to 18psig @ wot ---- Also pee stream pressure varies when at idle. Thanks for any info----

Would NOT necessarily be seen when changing the impeller. The passages in question are HIDDEN, and cannot be viewed adequately unless the shift-shaft bushing/plate are REMOVED. http://www.bassboatcentral.com/smileys/wink.gif

Don, i went thru all that with you last year. I got everything from you so i would have the seals and all. Everything was clear. I'm clueless
Stratospro, i have ordered parts from don to replace my pump again (it's probally dry rotted from not being used ) but i'm going to go over it again with a fine tooth comb and if i find anything i'll let you know.

Thanks, CRIMSONGAMBLER I am going to keep looking and checking for anything I can find to correct problem, will let you know if I find what is causing my problem. Has anything been mention about a possible bad adapter plate gasket ?

Gentlemen. I have the same motor as both of you(mine is a 2002 XB, s/n 0t6405830) with the TM gear case and low water inlets. The water pump in these motors is high volume and "low pressure" as intended. According to the service manual for this motor(90-822900R3), idle psi can range between 1 1/2-4 1/2 and pressure at 5000 RPM can be between a range of 8-10 psi minimum. I have seen variation of WOT pressure between 10-18 PSI depending on the height of my hydraulic JP. If the motor is not over heating(that would be real bad news), then is there a lot to worry about? Not understating the possibility of a major problem(s), and interested in everybody's outcome also. Please keep us all posted. Thanks. http://www.bassboatcentral.com/smileys/USA1.gif

What gets me is we have both seen 15+ on top end and idle at 4-5 then it's gone for no reason. The clicking noise im not sure where it was coming from, thought it might be the impellar key spinning on shaft. Taking it down next week.

similar thing happened to me last year on my 300x and it was a bad tuner gasket

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by onttr22 &raquo;</td></tr><tr><td class="quote">similar thing happened to me last year on my 300x and it was a bad tuner gasket</td></tr></table>

Although this is a "rough" way to check this.... while you have the gearcase off, it's a good idea to look up into the driveshaft housing (exhaust ports) with a BRIGHT FLASHLIGHT.

Observe the two rectangular "bell-shaped" openings for the tuner. Should you see gasket material "hooched" out into these openings, you can be relatively certain that the adapter plate (tuner) gasket is LEAKING.

There are also other possible leak points, which, unfortunately- you cannot observe without removing the powerhead/adapter plate.

Water pressure results should be relatively CONSISTENT, provided that setup is not altered (or substantial weight distribution changes in the boat made). http://www.bassboatcentral.com/smileys/wink.gif

Don, the only weight shift that has been done is my arse, lost about 50lb in the last 8 months. http://www.bassboatcentral.com/boardstuff2/beers.gif http://www.bassboatcentral.com/boardstuff2/beers.gif 6ft4in 218lb http://www.bassboatcentral.com/smileys/thumbsup2.gif

Don, if service manual says these motors run 8 to 10psig @5000 rpm do you think i sould be concerned that my motor is not running any more pressure than this with no alarm going off even though pressure in the past have been higher or do you think i should keep searching for a possible problem------- just seems everything that I have read about these motors have always indicated to run 15 to 18psig THANKS

Michael:

Just for kicks... try throwing about 50# of weight up around the driver's seat. Sandbag, etc, just to make sure it doesn't change your results. Congrads, BTW!

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by stratospro &raquo;</td></tr><tr><td class="quote">Don, if service manual says these motors run 8 to 10psig @5000 rpm do you think i sould be concerned that my motor is not running any more pressure than this with no alarm going off even though pressure in the past have been higher or do you think i should keep searching for a possible problem------- just seems everything that I have read about these motors have always indicated to run 15 to 18psig THANKS</td></tr></table>

Simply: IF your gearcase DOES NOT HAVE low water intakes (in the nose), you will only achieve 8-12 psi @ WOT.

If your gearcase DOES HAVE low water pickups in the nose... you should be at 15+ psi. http://www.bassboatcentral.com/smileys/wink.gif

The ONLY difference is the "ram pressure effect".

I'm going to go thru it again but if i dont find anything i'm not going to worry about it, i have had this motor for two years and had no problems with it at 10 psi, as long as the power head is getting water i dont see where the pressure will make that much difference. pressure build up means it is getting more than it needs.

If its a tuner gasket it will get worse.

I was running about the same as you, then my idle psi dropped to close to zero and the temp guage would start climbing during idling , replaced the gasket and now i have 20 psi plus at WOT and a strong 3 psi at idle. Never had 20 psi prior to replacing the gasket.

however id say that my gasket was leaking for at least two seasons.

One of the motors here in question was mine at one time. I bought it new and never seen over 15psi on a boat that runs low engine heights. Most of the time I could get 12psi but only after putting the water intake scopes one the side of the foot. I have since put a 250 pro xs on my same boat at the same motor height and hold about 25psi at wide open. I do not think for what ever reason that that motor will ever achieve 18psi in a ideal setup for our boats. I did talk to mother mercury factory teck back in 2002 or 2003 and was told that 10psi was more than enough due to the high volume low pressure aspect of the motor. Don is in the know on this and he and his post on water pressure is why I put the scopes on the side. Good luck with the issues and keep us up dated on what you find although I don't have the issue any more I am still interested in a fix.

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by EuropeanAM &raquo;</td></tr><tr><td class="quote">Simply: IF your gearcase DOES NOT HAVE low water intakes (in the nose), you will only achieve 8-12 psi @ WOT.

If your gearcase DOES HAVE low water pickups in the nose... you should be at 15+ psi. http://www.bassboatcentral.com/smileys/wink.gif

The ONLY difference is the "ram pressure effect".

</td></tr></table>

Most of the older EFI models (with twin ECU's on the back of the engine... including the XB's) are just fine in the 8-12 psi range. However, if the gearcase is replaced with a later-design unit (with pickups in the nose of the case), a water pressure increase "should" be noted.

Don, got the new pump in, checked the water passages from nose. It was clear, looked as best i could up in the tuner. Not able to see much with the angle it turns at but did not see anything out of place The seal that sits on top of pump was in place and working on the old set. Started her up and got instant water at peehole, pressure was at 4 1/2 at 800 rpm and 7 1/2 at 2000 rpm. Will be friday i hope before i can run down to the river, got a new razor-4 coming thursday. http://www.bassboatcentral.com/smileys/wink.gif

http://www.bassboatcentral.com/smileys/popcorn.gif Be sure to report back when you get to run it with the Razor.