Jabsco water pump failure - is it the pressure switch?

[CraigB]

Hi folks, having read through previous topics providing good advice about Jabsco water pumps I still have a query someone might be able to help with regarding my PAR-MAX 3 pump.

I think that I have a failed pressure switch but given the cost of replacing just this part, I'd appreciate a second opinion. The symptons are:

1. Initially, the pump started up once the water tap was opened, as you'd expect, but when closed, the pump continued to operate until I isolated it from the power supply.

2. It has also been noted that water is overflowing from the accumulator - I assume this is a pressure relief valve opening.

3. Also, at the time the pump failed to switch itself off, we detected a strong electrical/plastic burning smell.

Now, my question is whether anyone else has experienced this burning smell which I would normally associate with motor windings rather than a switch.

Given this scenario, would you bother replacing the pressure switch or go for a whole new pump and be done with it?

TIA
Craig

 

[spannerman]

Sounds like the pressure switch is u/s and the pump isn't cutting out and its labouring against the pressure in the accumulator which could be the reason for the burnt smell, is the pump motor housing getting warm?
I'd go for a whole new pump if its probably cooked.
Check the accumulator doesn't leak when the new pump is fitted as this could be faulty too.

 

[pvb]

As I recall, there's a little microswitch which switches the pump on and off, it's actuated by the pressure switch. It would be worth checking this microswitch first, because if that's the problem you could get a replacement from Maplin, etc, for only a few quid.

 

[CraigB]

Hi Steve. This is what I was afraid of - that even if the initial problem was the pressure switch, the problem may have been exacerbated due to the motor working against resistance, and thus I've ended up with two problems rather than one. You're probably right. Simplest solution would be to pay the £100 for a new pump and install it myself. Getting it repaired will probably be half the cost anyway, before any parts are added. Cheers, Craig.

 

[CraigB]

Hi pvb - yes, I have read that advice about the microswitch before, but the unit that comes off the bottom of the pump, which I believe is the whole pressure switch, seems to be sealed and I'm not sure how to get to the microswitch - anyway, I'll have another look at it tonight..

(Incidentally, it's the 12v 25psi version - 31600-0292)

 

[cliff]

On my Par Max 3 pump the micro switch is held in to the pressure switch housing by 2 white plastic pins that are easy to push out.
The maplin replacement switch is only rated at IIRC 12 amp but will do the job for a while. the higher rated 25amp switch is available from RS components but comes in a pack of 5. Still sheaper than a new pump (and you have 4 spare switches!)
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[pvb]

Current...

The 12v Par Max 3 has a recommended fuse size of 10A, so a 12A rated switch should be OK.

 

[CraigB]

Re: Current...

Cheers for that. Don't suppose you know the maplin or even the RS Components part number for these microswitches? It's just that I'll be going past a Maplins store before I get back to the boat again.

 

[pvb]

Re: Current...

No, don't know the part number, but I think microswitches are fairly standardised in terms of size, so just get the heaviest-duty one they have (Maplin staff are very helpful so will advise you).