1986 xp150 tach and water pressure problem

[joshuaray]

I am have 2 different issues. My tach works until I get between 1700-2000 rms then it quits. Will not work at all. Then when I drop back down below that it starts working again.
The other issue I am having is motor is **** in water has 2-4 psi at an idle. But my wot is only 8 psi. It has a new water pump housing and all. Also has new pressure relieve valves and thermostats. Motor is adjusted as low as possible. It is the correct lenght for the boat. Help with these 2 problems would be greatly appreciated. And I have tryed 2 different tachs on the boat. Both have the exact same problem.

 

[emdsapmgr]

Charging coils on the stator provide battery recharge voltage. When this charge coil fails, usually the tach quits. As you talk with folks, the tach acting up can take many forms, including the odd readings you are getting. Likely the stator is going bad. The impellers in these V4's and V6's are very robust. Usually last a long time. When new, they usually will pump 6-8 lbs at idle and maybe 20 at WOT. That's normal. The new parts in the stat housing have no bearing on the pressure. The pressure is read from the exhaust manifold, which is the first place the water goes when coming from the impeller/pump. This pressure should be independent of the stat housing. The stat housing is the last place the water winds up before it dumps into the midsection. So, is it possible that the hose barb that supplies the pressure gauge is plugged with debris? Have you pulled the hose off the line and run the engine? Do you get a good stream? Weedwhacker line is good to clean out the nylon hose barb, even the hose.

 

[joshuaray]

Yes there is a good stream. The **** stream is good at idle or wot. It is a new water pump and housing. Ty

 

[emdsapmgr]

Is the gauge accurate? If it got water in it last summer and it froze over the winter, that will affect the position of the needle on the bladder inside the gauge. And of course the accuracy of the pressure reading. I have to repl my gauge every 5-6 years when mine freezes over the winter and it won't read correctly.

 

[joshuaray]

It is a new gauge also. I was afraid of the old one not being accurate. I can't swear that this gauge is but it is new.

 

[emdsapmgr]

Is the gauge new to you, or was it purchased new from a dealer? It still might not read correctly...Any chance that the water pressure guage hose has a hole in it somewhere? A leaky hose can affect the gauge reading.

 

[joshuaray]

Brand new gauge. First boat it has been on. It is about a month old. The hose is new also. Changed them both at the same time.

 

[emdsapmgr]

Did you check the water intake screens in the lower unit? If you ever got the lower unit in the mud, those screens can plug up and restrict water flow. Probably can affect the pressure also.

 

[joshuaray]

Sorry I replied so slow. But yes they are clean. Screens are in place also.

 

[joshuaray]

Ty for trying to help me with this problem.

 

[Fed]

You could rig a temporary bridge rectifier to test with, cheap from electronic stores.
If the tacho works with that then you have eliminated the stator & the tacho as a problem and be left with the existing rectifier/regulator to deal with.
It sounds involved but really it should only be 4 wires on the terminal block.

 

[joshuaray]

Could you tell me how to do it.

 

[interalian]

Disconnect existing rectifier from the red and two yellow wires. Connect rectifier terminal + to the junction block's red terminal. Connect the ~ or AC terminals to the yellow and the yellow/grey terminals. Connect the - terminal to a ground screw. You can get a bridge rectifier like this for a few bucks - use the center hole to mount it to the engine and make some ring to spade lug cables to wire it up to the terminal block. It'll actually work just as well as what you have on the motor now.

http://www.germes-online.com/direct/..._Rectifier.jpg

 

[joshuaray]

Thanks I will give it a try.

 

[joshuaray]

Interalian I believe my rectifier is different from how you said to wire it. The one in the pic on the link is different. Mine bolts to the block and has 5 wires coming out the top. They are epoxied in. Part number is 584423-10ax. I have a red wire that goes to starter sil. Then I have a gray, purple, yellow, & yellow gray strip. That go to side of the motor on the strip. What wire do I need to move and hook up. Help is greatly appreciated.

 

[joshuaray]

I see what you are saying now. I will need to get one of those. Will it hurt anything to leave it on the motor long term. Does this just replace the existing rectifeir or just to test with.

 

[joshuaray]

Ok my rectifier is different. While looking it up I found where someone said on a different post that you can just hook it up to the yellow and gray wire. So I did that and tach would still die between 1650 and 17oo rpms. And that is the same thing it was doing hooked up to just the gray wire. But today it quit working at all hooked up to the gray wire. So does that mean that my rectifeir and stator are both going bad.

 

[joshuaray]

My motor is an 1986 xp150

 

[emdsapmgr]

I'd hold off on replacing the stator. Likely the water cooled rectifier/regulator is at fault. Start there first, as the stator is very expensive and may not be faulty. When the rectifier/regulator goes, it can fail in a number of different modes. (the faulty part can show different failures, all of which lead back to the fact that the rectifier/regulator is bad. )

 

[joshuaray]

Ok think you for the advise. I found it odd that when I took the rectifier out of the situation that it still had a problem so I figured it had to be both of them.