Bravo 1 water pressure issues

[skyman2112]

Hi group, how can i increase the water pressure especially at idle? Bought this boat new in 2011 and after the first few years its been hard to keep the alarm from going off and even went into gaurdian mode a few times a year. I been to the dealer and they ran it with a clear hose attached and it didnt show any signs of air. Replaced the pump housing and impeller several times and the water pressure sensor 3 times but still it barely has enough pressure to keep the alarm off. I finally bought my own scan tool so i could monitor it while driving.
The water pressure varies from 0.7 to 3 psi at idle. If i give it some gas when i start it then go back to idle, the pressure seems to stay higher. And at cruise i have. about 10-12psi at 3300rpm. Alarm goes off mostly when its warmed up. and less often when I first start it cold, i/e the thermostat is closed, So I changed the poppet valve spring thinking maybe that was stuck open but the old spring was fine.Water temp is always good, lots of volume too. any ideas no matter how crazy would be appreciated. Can i adjust the pressure sensor to read higher somehow? Install a resistor? Anything to keep the computer happy on my otherwise perfectly running 377Mag with catalyst exhaust. S/N 1A645849

 

[bman440440]

you might have a case of bravoitus search the forums on it and you will get the info you need

 

[tpenfield]

The boat seem fairly new for Bravoitis, but maybe. It does not sound like anyone has checked the oil & PS fluid coolers for clogs. I'd look there to see if there is a blockage.

does the scan tool show the engine temperature that the ECM is reading while underway? Has the operating temperatures (idle & cruising) risen recently? Do you know what the spec is for water pressure?

 

[alldodge]

Thanks for the serial number
Does the boat have open or closed cooling, and 3 or 7 point drain system?

The water pressure varies from 0.7 to 3 psi at idle. If i give it some gas when i start it then go back to idle, the pressure seems to stay higher. And at cruise i have. about 10-12psi at 3300 rpm.

This is the the issue of your problem. The Bravo drive pump should supply close to 3 psi cold, and a tad less warm at idle. It should also supply something at least 20 psi at cruise and a tad higher at WOT, up to 30 psi

 

[skyman2112]

The boat seem fairly new for Bravoitis, but maybe. It does not sound like anyone has checked the oil & PS fluid coolers for clogs. I'd look there to see if there is a blockage.

does the scan tool show the engine temperature that the ECM is reading while underway? Has the operating temperatures (idle & cruising) risen recently? Do you know what the spec is for water pressure?

hoses are clean inside no blockage, seems like tons of water flow, temp never goes above 160/

 

[skyman2112]

Thanks for the serial number
Does the boat have open or closed cooling, and 3 or 7 point drain system?



This is the the issue of your problem. The Bravo drive pump should supply close to 3 psi cold, and a tad less warm at idle. It should also supply something at least 20 psi at cruise and a tad higher at WOT, up to 30 psi

i will run it today and see what the cruise psi is, im sure its not that high though. I think its 3 point drain i see hoses coming off the block only. You think its a problem between the lower unit and pump? The shop said it had lots of water flow but maybe that was just subjective.

 

[Bt Doctur]

have you tried replacing the water pressure sensor?

working on a resistor package for that pesky sensor,

 

[alldodge]

I'm am assuming you have open cooling and not closed (uses antifreeze).

With the low pressure and new impellers, I would be thinking there is not enough restriction going out, or there is something causing a restriction coming in. In the picks attached is the new style thermostat housing which uses a spring loaded poppet valve.

Also show what Merc calls the "new" MPD which is actually the old 7 point (sure glad they started offing this again). The other is the 3 point system. The 3 point has the distribution and drain valve on the port side. This valve also has a Tee fitting above to help restrict flow and also is used to drain

The poppet valve restricts water flow going to the risers to help keep everything full. They use to use spring loaded check balls in these lines and guess they think this is better, don't know because it has not been out that long.

Has the poppet valve been checked for operation?

 

[skyman2112]

I'm am assuming you have open cooling and not closed (uses antifreeze).

With the low pressure and new impellers, I would be thinking there is not enough restriction going out, or there is something causing a restriction coming in. In the picks attached is the new style thermostat housing which uses a spring loaded poppet valve.

Also show what Merc calls the "new" MPD which is actually the old 7 point (sure glad they started offing this again). The other is the 3 point system. The 3 point has the distribution and drain valve on the port side. This valve also has a Tee fitting above to help restrict flow and also is used to drain

The poppet valve restricts water flow going to the risers to help keep everything full. They use to use spring loaded check balls in these lines and guess they think this is better, don't know because it has not been out that long.

Has the poppet valve been checked for operation?

Yes sir i just replaced that spring with a new one, old one looked fine. I have the 3 point system as pictured above. Ran the boat again today and checked the PSI at every engine speed and noticed something very odd. The pressure never goes above 13psi from 3000-5000 rpm. The number fluctuates between 12 and 12.8 the whole time. Even with a restriction or whatever i dont see how this is possible, as the pump spins faster the pressure should change somewhat regardless of any other problems.I could try putting another sensor on it for the 4th time and see if it makes a difference. I think your right theres not enough back pressure, too much volume. See the following post.

 

[skyman2112]

I didnt realize theres another valve in the distribution housing on the port side. I think your on to something here. It acts like there is too much volume and not enough back pressure. Thats why i can never get enough pressure even at high RPMS. Its the only thing I HAVENT changed. Is it serviceable or just get a whole new distribution valve.

heres some pics of the new poppet valve spring and the impeller i removed with 20 hours on it. Notice there is no grooves in the pump housing and the impeller doesnt have a scratch on it. I put a new one in anyways when i put it back together since its already apart. Still get the same psi reading from 3000-5000 rpm. Fluctuates from 12-13 its not a steady reading. When i start it cold i get about 4psi and when the thermostat opens it drops to about 1.5 to 2psi..Another indication of too much volume. Sometimes when i restart it the pressure as low as .5 psi but levels off above 1 after about 10 seconds

 

[scoflaw]

My last boat had similar pressure numbers as yours for the six years I owned it.. Ran perfect , temp spot on and ECM was happy with no alarm. Maybe your problem lies elsewhere.

 

[alldodge]

Just to check you are using the correct impeller,

Bravo Gen 2 & 4 pumps 47-59362T1 OD 2.63 Width 2.01
Bravo Gen 7 pump 47-862232A2 OD 2.50 Width 2.25

 

[skyman2112]

My last boat had similar pressure numbers as yours for the six years I owned it.. Ran perfect , temp spot on and ECM was happy with no alarm. Maybe your problem lies elsewhere.

ah ok, so you had no increase in pump pressure from 3000-5000 rpm the same as me?

 

[skyman2112]

Just to check you are using the correct impeller,

Bravo Gen 2 & 4 pumps 47-59362T1 OD 2.63 Width 2.01
Bravo Gen 7 pump 47-862232A2 OD 2.50 Width 2.25

Yup its for gen 7. small shaft. Didnt the gen 2 and gen 4 have a bigger shaft? Or are there 2 different sizes for the small shaft design? So what about the distribution valve could it be stuck open and be allowing too much volume? Can it be repaired?

 

[Bt Doctur]

Its the only thing I HAVENT changed. Is it serviceable or just get a whole new distribution valve.


Save your money, theres nothing inside it anyway

 

[alldodge]

Yup its for gen 7. small shaft. Didnt the gen 2 and gen 4 have a bigger shaft? Or are there 2 different sizes for the small shaft design? So what about the distribution valve could it be stuck open and be allowing too much volume? Can it be repaired?

Never found any difference in info on shaft size so I'm pretty sure its the same size. It has been found that some have installed the wrong impeller.

The distribution valve is basically a ball with 3 openings (Tee fitting), and the smaller Tee fitting above will reduce the size opening to restrict the flow. These previous Tee's had all the same size openings and bushings were installed in the two feeding the risers. Newer style have the Tee pre made with smaller exits

 

[skyman2112]

Its the only thing I HAVENT changed. Is it serviceable or just get a whole new distribution valve.


Save your money, theres nothing inside it anyway

Ah ok its just a fitting with no moving parts. Gotcha. Well is 13psi enough pressure at 5000 rpm? What is the computer alarm set for any idea?

 

[skyman2112]

Its the only thing I HAVENT changed. Is it serviceable or just get a whole new distribution valve.


Save your money, theres nothing inside it anyway

OK so if the pump housing and impeller are new and so is the pressure sender, and it always runs cool and has tons of water flow, how do i keep the low pressure water alarm from sounding?

 

[skyman2112]

Yup its for gen 7. small shaft. Didnt the gen 2 and gen 4 have a bigger shaft? Or are there 2 different sizes for the small shaft design? So what about the distribution valve could it be stuck open and be allowing too much volume? Can it be repaired?

My part number is 47-8M0104229.

 

[skyman2112]

My last boat had similar pressure numbers as yours for the six years I owned it.. Ran perfect , temp spot on and ECM was happy with no alarm. Maybe your problem lies elsewhere.

well the code of my techmate pro scan tool says low water pressure so if the pump housing and impeller and pressure sender are all new what else can i do? Its got tons of water flow and always runs cool. Recalibrate the computer?