Weirdness With Jabsco Sensor Max 14 pump

[Jd1]

A couple/three weeks ago my potable fresh water pump died. Specifically it started out as the water pump breaker popping after maybe a minute or so (but the pump still working while the breaker was on) and then it stopped completely. I checked voltages at the pump leads and they were fine. I decided the pump was dud (also a Jabsco Sensor Max 14) and installed the replacement. Replacement worked fine and in my eyes this proved the pump to be dud. About a week ago, I took the dud pump home, hooked it up to a power supply and wonders of wonders, it worked fine. Made a mental note that maybe the motor has a sticky spot or something similar and brought the old pump back to the boat as an emergency spare. Forward to today, I open the faucet and no water ...... damit !!!! The problem is exactly as before. There is power to the pump but the motor doesn't turn on. I disconnected the output hose from the pump in case there was a plumbing issue but no, there was no pressure.
I could make an assumption that both pressure sensors were bad ... but this is a brand new (10 years old but new in the box) pump and the chances of both pumps having the exact same symptoms seems remote.
Has anyone run into this before? Are the sensors on these prone to failure and it's my lucky day or am I somehow missing something here ?

[topmast]

Most pumps I'm familiar with can be jiggered by shorting out the wires to the pressure sensor .Then it's the sensor,pump or lack of voltage. (like an intermittent dead short or break in the wire somewhere .The little micro switch on a diaphragm is the same as in a micro wave door and are easily checked /replaced

[Jd1]

Based on my testing, it would appear that the electronics for the variable speed system have up and died on both pumps although the old pump failure seems intermittent. I have been unable to find the required parts - seems the variable speed electronics is always sold as part of the motor and is not available separately.
I would like to replace the pump with another variable speed system but only if the electronics of the variable speed drive are replaceable. At least with Jabsco that is the part that seems to fail most often.
I would be grateful for any suggestions of a decent quality variable speed pump.

I would like to add that I am impressed about how the Jabsco pump is put together - too bad that the electronics are not available for replacement (and that they are prone to failure)

[Jd1]

Today I confirmed that the variable speed drive electronics are intermittent on both pumps. On occasion they just decide to work ... go figure. There is one 8 pin IC inside that is in a regular socket. I re-seated it on both pumps hoping that it was a bad connection but no such luck. Removing the circuit board and checking for bad solder joints is not really possible due to the way it is attached to the back cover of the motor.

Still hoping that somebody might have suggestions on a decent replacement .....

[jamhass]

There is a guy in Socal who does rebuild these, or at least used to. Haven't contacted him in a couple of years and don't have his info. Google might help.

A backup plan that I have used is to "hot wire" across the internal circuit board. Pump will operate, but not shut off, so you must manually turn it on or off. Not ideal, but an easy under way fix. The next step in jury rig is to put a pressure switch in the output line. Home Depot sells pump pressure switches for 20 bucks or so.

[Jd1]

Originally Posted by jamhass

Home Depot sells pump preussure switches for 20 bucks or so.

That is an EXCELLENT suggestion!! I was contemplating how to retrofit a switch to the existing pump but never thought of an external switch. The only thing that has me worried is the pressure range for household use and the (assumed) 120V AC switch rating. Thing is, now that you have mentioned this idea, I can go looking and if the Home Depot switch isn't suitable, I am sure there will be others.
The concept of throwing two perfectly good pumps out just wasn't sitting well with me (plus the costs add up if I buy two - one to install and one spare)
Just got to find a spot for an accumulator.

[Privilege]

This is a review I wrote for the variable speed pump...may well be the same problem..

The pump kept shutting off so I narrowed down the problem and eventually worked out that the pump is sensing an over-voltage problem at 14.4v and shuts itself down. The installation manual states that this is supposed to happen at 14.5v. The trouble is, my charging system is set to charge my AGM batteries at 14.4v so whenever the sun is shining and my solar panels are putting out full voltage to my smart controller, the pump shuts down. I contacted Shur-flo but all they did was confirm that I had identified the problem. The options I have now is to alter the charging output to a slightly lower voltage, which of course makes no sense just to accommdate one pump, or to place a resistor in-line to lower the voltage to the pump. The pump works great when running straight from the batteries at 12.4v, but working 'most of the time' is of little use to me.

[Jd1]

Originally Posted by Privilege

This is a review I wrote for the variable speed pump...may well be the same problem..

Thanks for the suggestion but this is not the problem in my case.

[Jd1]

Thanks again Jamhass. For around $40 (Canadian) I acquired the bits needed for the pressure switching and about $85 still needs to be spent for an accumulator tank and required fittings. The old pump has decided to work again for now so it has been installed, the new pump will go home with me tonight to either fix the electronics or convert to fixed speed operation (or maybe both, just in case .... bring out an extra set of leads). In any case, the plan is well mapped out thanks to your 'out of the box' thinking!
Bonus: I can now change a water pump in 5 minutes flat (with the quick fittings)

[Captain Bill]

How did you determine it was the electronics in the pump? Your symptoms could be caused by a loose/high resistance connection in the power supply. While there is no load on the connection one can often read normal voltage at the wires but the connection cannot conduct the amperage to actually make the pump run. Remember the bad connection could also be on the ground side, not just the + side.

[Jd1]

Originally Posted by Captain Bill

How did you determine it was the electronics in the pump? Your symptoms could be caused by a loose/high resistance connection in the power supply. While there is no load on the connection one can often read normal voltage at the wires but the connection cannot conduct the amperage to actually make the pump run. Remember the bad connection could also be on the ground side, not just the + side.

Fair question. Both pumps worked occasionally (although the new pump is now dead).
There is power on the input. The input goes straight to the variable speed electronics which is mounted on a small circuit board together with the motor brushes. As the motors were not dead dead, I made an assumption that the armature of the motor is ok. That only leaves the little circuit board. Yes, I suppose it could be other stuff but I doubt it. There doesn't seem to be any overheat issues of any of the components but the traces and soldering is not accessible as the board is riveted in place. Because the brushes are on the circuit board, board location is critical and I decided to not push my luck. I will investigate if there are mounting bosses that can be used for locating the board and if there is enough 'meat' to replace the rivets with tiny screws. It looks like the rivet is not a rivet as such but an expanded boss on the motor end plate. Removing the boss will prevent proper registration of the circuit board and convert the motor into a door stop.
So, if it looks like I can re-attach the circuit board I will remove it and check for cold/bad solder joints. If it looks like I can't remove the board without buggering things up I will bypass the electronics.
The fact that somebody at some time repaired these things gives me hope that I might be able to fix things. Any fix applied to one pump will also be applied to the other pump.

[jamhass]

In both of my pumps that suffered similar symptoms, I found damaged components and/or other signs of overheating.

[Jd1]

The deed is done, the new pump is converted to full speed

There were no obvious sign of overheating, no visible trace breaks or bad solder joints. I did not attempt to diagnose the problem to the component level but just connected the power leads directly to the brushes.