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Replacing a water pump


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29 minutes ago, philjw said:

Is the valve core loose?  I think if it is not then I would change the core for a new one. They and the tools you need are available from car spares shops. Just a case of unscrewing the old one and screwing in the new one.

Thanks for your reply. In answer to your question: I don't know. Everything at the business end of the accumulator is being done by feel. The valve of the accumulator is almost butted up against the side of the boat. I can barely get my fingers in there to unscrew the valve cap (and I've got small hands) and am doing so almost blindly. The photo below shows all that I can see.

So given that, what exactly is a valve core? How can I tell if it's loose, please? How do I tighten it if it is loose? And if not, how do I replace one? (As a heads up, any bike or car tyre analogies will be lost on me as I don't partake in either 😉)

20201121_142844_resized.jpg

Edited by BlueStringPudding
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3 minutes ago, BlueStringPudding said:

Thanks for your reply. In answer to your question: I don't know. Everything at the business end of the accumulator is being done by feel. The valve of the accumulator is almost butted up against the side of the boat. I can barely get my fingers in there to unscrew the valve cap (and I've got small hands) and am doing so almost blindly. The photo below shows all that I can see.

So given that, what exactly is a valve core? How can I tell if it's loose, please? How do I tighten it if it is loose? And if not, how do I replace one? (As a heads up, any bike or car typre analogies will be lost on me as I don't partake in either 😉🤔

 

 

Unless you have a valve tool I don't see how you can tell if its loose. Do you have a car? If so look at the valve caps on all the tyres, most will be plastic but one might be metal with a very different shape. the top will have a sort of tube on it with a cut out at either side at the open end. This is a valve tool.

 

The tube fits down the blowing up point and the cut outs fit onto flats on the valve so you can screw the valve in or out. Once you see the thing you will realise its not hard to do by feel. So fit the tool and try screwing the valve in. if it twists all well and good, if it won't then unscrew it and fit a new one. I bet if you go to a tyre place and smile sweetly they will give you a valve for free.

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7 minutes ago, Tony Brooks said:

 

Unless you have a valve tool I don't see how you can tell if its loose. Do you have a car? If so look at the valve caps on all the tyres, most will be plastic but one might be metal with a very different shape. the top will have a sort of tube on it with a cut out at either side at the open end. This is a valve tool.

 

The tube fits down the blowing up point and the cut outs fit onto flats on the valve so you can screw the valve in or out. Once you see the thing you will realise its not hard to do by feel. So fit the tool and try screwing the valve in. if it twists all well and good, if it won't then unscrew it and fit a new one. I bet if you go to a tyre place and smile sweetly they will give you a valve for free.

No, I don't drive so I don't have a valve tool. But thanks for your explanation. 😊

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https://www.eurocarparts.com/p/schrader-valve-repair-tool-black-539770371?type=shopping

This is a typical tool. You use the part that has a couple of lugs to remove the core.

From the photos it looks like you would have to break a joint in the pipe that runs parallel to the accumulator then swivel the accumulator to gain access. Turn off the pump first though.

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On 11/11/2020 at 19:57, BlueStringPudding said:

 

Current leaking pump that I'm trying to get a good match for the spec, but it's no longer made (parts may be obtainable for a repair but it's a very old pump):
JABSCO 30620-0292 PAR MAX 4
12v
Flow 14.4lpm
Cuts in at 10psi
Cuts out at 20psi
6A draw
10A fuse

Available To buy:
JABSCO 31620-0292 PAR MAX 4
12v
Flow 16.3lpm HIGHER
Cuts in at 10psi CORRECT
Cuts out at 25psi TOO HIGH
6A draw (on pdf spec sheet) CORRECT
10A fuse (on pdf spec sheet) but contradicted on website as 15A fuse.  TOO HIGH

 

Sorry, late to the party, but I would say these are the same pump. All that has happened is that the current version has been uprated to operate at a higher pressure, and hence to give a higher flow and draw more current in the process. If you can either adjust the cut-out pressure down to 20psi, or use a separate pressure switch set to 20psi, the performance will be pretty much the same as your existing pump. 10A fuses will probably be fine, but you might want to invest in a pack of slow blowing fuses to cater for surge current when the pump starts.

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18 minutes ago, philjw said:

https://www.eurocarparts.com/p/schrader-valve-repair-tool-black-539770371?type=shopping

This is a typical tool. You use the part that has a couple of lugs to remove the core.

From the photos it looks like you would have to break a joint in the pipe that runs parallel to the accumulator then swivel the accumulator to gain access. Turn off the pump first though.

I suspect the OP will not be able to get that into the gap between valve and timber baton, let alone remove the valve.

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15 minutes ago, Tony Brooks said:

I suspect the OP will not be able to get that into the gap between valve and timber baton, let alone remove the valve.

Agreed. That's why I suggested breaking a joint in the pipework to allow the accumulator to twist at the tap connector towards the vertical to allow easy access to the valve.

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2 hours ago, philjw said:

Agreed. That's why I suggested breaking a joint in the pipework to allow the accumulator to twist at the tap connector towards the vertical to allow easy access to the valve.

PersonallyI would take a big drill and chisel to the batten.

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On 11/11/2020 at 19:57, BlueStringPudding said:

Yes. I do want to be 100% sure it will all work without more problems. Pretty basic expectations though, don't you agree? 😃

 

But I don't for one minute believe that a pump with a flow of 7lpm or 3lpm will be give anywhere near as decent a shower as one with a flow of 14.4lpm at 10-20psi. That's just common sense, surely? 

 

Trying to compare Jabsco pumps is hard enough, but I've just noticed that the spec on their website is contradicted by the spec for the same model on the pdf. One spec would be an adequate replacement, the other needs a bigger fuse. Which one is a typo? Who knows!? Aargh!

 

Looking at Jabsco 10A only pumps, coz I'm stuck with the electrics I've got, these are the options:

 

Current leaking pump that I'm trying to get a good match for the spec, but it's no longer made (parts may be obtainable for a repair but it's a very old pump):
JABSCO 30620-0292 PAR MAX 4
12v
Flow 14.4lpm
Cuts in at 10psi
Cuts out at 20psi
6A draw
10A fuse

Available To buy:
JABSCO 31620-0292 PAR MAX 4
12v
Flow 16.3lpm HIGHER
Cuts in at 10psi CORRECT
Cuts out at 25psi TOO HIGH
6A draw (on pdf spec sheet) CORRECT
10A fuse (on pdf spec sheet) but contradicted on website as 15A fuse.  TOO HIGH

JABSCO 31395-0392 PAR MAX 2.9
12v
Flow 11lpm LOWER
Cuts in at 20psi MUCH TOO HIGH
Cuts out at 40psi MUCH TOO HIGH
4.4A draw LOWER
10A fuse CORRECT

JABSCO 31600-0092 PAR MAX 3
12v
Flow 13lpm A BIT LOWER
Cuts in at 20psi MUCH TOO HIGH
Cuts out at 40psi MUCH TOO HIGH
Draw ?
Fuse 10A CORRECT

So it's not looking great for 10A fused pumps in terms of psi - and that's not just with Jabsco. Looking at Midland Swindlers 10A only pumps, there's

JABSCO PAR MAX 7l

12v

Flow 7lpm LESS THAN HALF, TOO LOW

Cuts in at ?

Cuts out at 25psi TOO HIGH

Draw 3.5A OKAY 

Fuse 10A CORRECT

 

WHALE PUMPS TOO TALL AND WRONG SHAPE FOR PRESENT INSTALLATION

 

JABSCO PAR MAX 1

12v

Flow 3.7lpm TOO LOW

Cuts in at ?

Cuts out at 35psi TOO HIGH

Draw ?

Fuse 10A CORRECT

 

SHURFLOW AQUA KING 2 JUNIOR

12v

Flow 7.6lpm TOO LOW

Cuts in at ?

Cuts out at 20psi CORRECT

Fuse 3.5A (weirdly low - can't be powerful enough, surely?)

 

All other SHURFLO have much too high cut out psi.

 

(I just thought to check the destructions for the toilet plumbing, as I aspire to have it flushing properly with fresh water one day and I vaguely recall it had a minimum requirement from the water system. It needs a water pump with a flow of at least 11lpm. So that narrows down the water pump choices with one fell swoop - the piddly ones won't work). 

 

So for now, those are my options. None took good to me. A phone call to Jabsco to get them to verify the fuse rating of the 31620-0292 Par Max 4 might be sensible since they haven't answered my email yet. If they confirm it needs a 15A fuse not a 10A, then it looks like I need to try replacing some parts on the old leaking pump. Not my area of expertise, obviously. 😔

A little late into this topic. I've been looking at the Parmax 3.5 13LPM with 10/25psi respectively:

 

https://www.marinesuperstore.com/marine-pumps/fresh-water-pumps/jabsco-parmax-3-5-pressure-controlled-pump-12v?utm_source=google_shopping&utm_medium=pcn&utm_term=02254&utm_campaign=MSS&gclid=EAIaIQobChMIrOy7lYz07AIVWe7tCh2atwchEAYYASABEgLUgfD_BwE

 

And from MC

https://www.midlandchandlers.co.uk/products/jabsco-32600-0292-par-max-3-5-pressure-pump-12v-13-lpm-25-psi-wp-012

 

 

Edited by Markinaboat
PIS instead of PSI!
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14 hours ago, BlueStringPudding said:

 

20201121_142844_resized.jpg

 

Why is the pump plumbed in with hard connections? It should be connected with two short lengths of flexible hose to reduce noise and vibration. Jabsco Parmax pumps are supplied with hose connectors for this purpose. Connections in rigid pipe are also more prone to leaks but for some reason that's what we see on 9 out of 10 boats.

Edited by blackrose
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4 hours ago, blackrose said:

Mine chirp when the batteries need replacing. They seem to last a few years

 

Thanks,

 

I'll try leaving one of mine longef to see if it eventually chirps. Could save a small fortune in PP9 batteries.

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Next phase of this pain in the bum water pump replacement. It's genuinely brought me to a point of despair now. 

 

I bought the tools and valve core replacement bits for the accumulator online. Replaced the core. Nearly killed myself pumping the ruddy thing up then lost a load of the pressure when I unscrewed the bike pump. Grr.

 

After some recovery time, I replaced the valve core again and this time asked Tree Monkey to pump the accumulator up to approx 7psi. He did, then he successfully took the bike pump off and I ran the kitchen tap for 30 seconds or so - it worked perfectly. Much jubilation. Tree Monkey went home. Both happy bunnies (or monkeys). 🐰🐵

 

I turned the kitchen taps back on five minutes later to do some washing up, there was some spluttering at the tap like air in the pipes and then I was back to a cycling pump as if there was no accumulator again! 😭 I turned on other taps throughout the boat and there was the same alternating fast-slow flow.

 

Monkey came over and checked the pressure at the accumulator - 8point-something so a little high (it should be about 7psi for a 10psi cut-in pump, according to the accumulator manual) But it obviously hadn't lost much if any pressure and should have been working. But still the water was running fast-slow and the pump was cutting in and out.

 

Tree Monkey did some more fettling, reducing the pressure in stages as I tested the taps throughout.  Eventually the two sinks closest to the pump now have adequate flow but with some fluctuation in speed. However the bathroom outlets further away are showing the changes in flow speed the same as before the accumulator had any pressure introduced! I don't know why. And it'll make for a lousy shower as it's worse when the hot tap is open. 

 

The pump is cycling on and off causing the increase and decrease in flow at the same time; and sometimes the pump judders too. When it judders the water flow does too.

 

Can anyone please shed any further light on what is causing this? 

 

Link to a video below (turn the sound up) showing how the pump is behaving with a bathroom tap on fully open, followed by a view of one of the bathroom fittings being affected by this. This fluctuating water flow did not happen with the old Jabsco pump, and both it and the new pump used the same accumulator. I'm guessing I've still not set something correctly on the accumulator? 

 

There's a description under the video which explains the details of the set-up if needed. If we can't get our heads around it here, I can at least email a link to the video to the chaps at Jabsco technical support. But before I do - any thoughts please?

 

https://youtu.be/CXiFCOROWKY

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On 21/11/2020 at 20:40, Markinaboat said:

I've since realised the 3.5 is the noisy one that Jabsco do (in their own admission) and is either discontinued (but available) or due to be. So will go for the par max 4 or the par max 4 plus which apparently has an improved pump for longer life and 15lpm.

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54 minutes ago, BlueStringPudding said:

Next phase of this pain in the bum water pump replacement. It's genuinely brought me to a point of despair now. 

 

I bought the tools and valve core replacement bits for the accumulator online. Replaced the core. Nearly killed myself pumping the ruddy thing up then lost a load of the pressure when I unscrewed the bike pump. Grr.

 

After some recovery time, I replaced the valve core again and this time asked Tree Monkey to pump the accumulator up to approx 7psi. He did, then he successfully took the bike pump off and I ran the kitchen tap for 30 seconds or so - it worked perfectly. Much jubilation. Tree Monkey went home. Both happy bunnies (or monkeys). 🐰🐵

 

I turned the kitchen taps back on five minutes later to do some washing up, there was some spluttering at the tap like air in the pipes and then I was back to a cycling pump as if there was no accumulator again! 😭 I turned on other taps throughout the boat and there was the same alternating fast-slow flow.

 

Monkey came over and checked the pressure at the accumulator - 8point-something so a little high (it should be about 7psi for a 10psi cut-in pump, according to the accumulator manual) But it obviously hadn't lost much if any pressure and should have been working. But still the water was running fast-slow and the pump was cutting in and out.

 

Tree Monkey did some more fettling, reducing the pressure in stages as I tested the taps throughout.  Eventually the two sinks closest to the pump now have adequate flow but with some fluctuation in speed. However the bathroom outlets further away are showing the changes in flow speed the same as before the accumulator had any pressure introduced! I don't know why. And it'll make for a lousy shower as it's worse when the hot tap is open. 

 

The pump is cycling on and off causing the increase and decrease in flow at the same time; and sometimes the pump judders too. When it judders the water flow does too.

 

Can anyone please shed any further light on what is causing this? 

 

Link to a video below (turn the sound up) showing how the pump is behaving with a bathroom tap on fully open, followed by a view of one of the bathroom fittings being affected by this. This fluctuating water flow did not happen with the old Jabsco pump, and both it and the new pump used the same accumulator. I'm guessing I've still not set something correctly on the accumulator? 

 

There's a description under the video which explains the details of the set-up if needed. If we can't get our heads around it here, I can at least email a link to the video to the chaps at Jabsco technical support. But before I do - any thoughts please?

 

https://youtu.be/CXiFCOROWKY

 

As I keep saying and despite what Jabsco told you accumulators can not stop pumps cycling (pulsing on and off) if the pump is delivering more volume than can flow out of the taps. However this shoudl not cause spluttering, just a variable flow. An accumulator will extend the on - off periods of the cycle though so it may seem as if it stopped cycling when filling a kettle. Much of the shower sequence seems close to cycling with an accumulator but the motor juddering on and off is not normal and if it does that while the flow from the shower reduces I would suspect a motor or pressure switch fault. its very strange.

 

Is it a variable speed pump or a bypass valve one? I know the variable speed pumps have had reliability issues in the past. Not sure how a bypass valve pump could cause that.

 

Spluttering sounds more like air in the system to me so as long as the accumulator is holding pressure it can't be air from blowing it up leaking through the diaphragm. I would be looking for a poor connection or a blockage on the inlet side of the pump.

 

the fact the taps at the further end of the pipe runs cause cycling whilst some closer to the pump do not may be expected because the longer pipe runs will case resistance to flow so there is a pressure drop at the remote taps causing  a lowwer flow volume form the taps while the pump still  delvers the same volume as always.

 

Note - This applies ro standard pumps, not pumps with a bypass valve or variable speed pumps.

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21 minutes ago, Tony Brooks said:

Much of the shower sequence seems close to cycling with an accumulator but the motor juddering on and off is not normal and if it does that while the flow from the shower reduces I would suspect a motor or pressure switch fault. its very strange.

 

Is it a variable speed pump or a bypass valve one? I know the variable speed pumps have had reliability issues in the past. Not sure how a bypass valve pump could cause that.

 

 

I don't know which of those types of pump it is (or what they mean!). This is the information I know about it (from the Jabsco website):

 

Par Max 4' pressure-controlled pump
31620-0292
12 volt d.c., Standard Pressure
  • Connections: for 13mm (½”) bore hose or Hep20 push-fit connectors CW193
  • Dimensions: 250mm long, 105mm wide, 100mm high
  • Fuse Size: 15(amp)
  • Output: 16 litres/minute (3.5 gallons/minute) open flow
  • PRESSURE SWITCH - cuts in at 0.7bar (10psi) - cuts out at 1.7bar (25psi)
  • Efficient, high-flow, self-priming pump serving 4 or more outlets
  • Multi-diaphragm design self primes to 1.5m vertical lift, can run dry without damage
  • Supplied with snap-in ports for hose or Hep20 connectors
  • Motor protected by automatic thermal overload cut-out
  • Packaged Dimensions: L:17.00 x H:11.00 x W:34.00cm
  • Actual Weight: 2.97 Kg  (Approx. 3.47 Kg packed

https://www.jabscoshop.com/marine/pumps/pressurised-fresh-water-pumps/31620-0292-par-max-4-pressure-controlled-pump.htm

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1 hour ago, BlueStringPudding said:

I don't know which of those types of pump it is (or what they mean!). This is the information I know about it (from the Jabsco website):

 

Par Max 4' pressure-controlled pump
31620-0292
12 volt d.c., Standard Pressure
  • Connections: for 13mm (½”) bore hose or Hep20 push-fit connectors CW193
  • Dimensions: 250mm long, 105mm wide, 100mm high
  • Fuse Size: 15(amp)
  • Output: 16 litres/minute (3.5 gallons/minute) open flow
  • PRESSURE SWITCH - cuts in at 0.7bar (10psi) - cuts out at 1.7bar (25psi)
  • Efficient, high-flow, self-priming pump serving 4 or more outlets
  • Multi-diaphragm design self primes to 1.5m vertical lift, can run dry without damage
  • Supplied with snap-in ports for hose or Hep20 connectors
  • Motor protected by automatic thermal overload cut-out
  • Packaged Dimensions: L:17.00 x H:11.00 x W:34.00cm
  • Actual Weight: 2.97 Kg  (Approx. 3.47 Kg packed

https://www.jabscoshop.com/marine/pumps/pressurised-fresh-water-pumps/31620-0292-par-max-4-pressure-controlled-pump.htm

 

I think its a perfectly standard type pump so I can't see what would cause the pump to behave like that (the "stuttering") I think it might be a good idea to double check the cleanliness and tightness of all the connections on the water pump electrical circuit and also as a test bypass the boat's water pump switch and fuse in case its a dodgy connection breaking as the current rises as the pressure increases.

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I've just done a couple of quick electrical experiments. It seemed to go well till I took out the wiring of what I thought was the isolation switch to the pump (installed by a previous owner). 😁 I've put the readings below. Measurements 1 and 2 have made me wonder if the water pump is cutting out when the voltage drops rather than when the accumulator gets to pressure?  Or can anything else be read into these numbers (other than the fact I maybe nearly set fire to the boat during measurement 3 and 4)? 🤔 Would love your feedback please, people in the know.

 

Incidentally, the readings that were taken at the pump end of the boat were taken at the spade connectors between the pump cables and the boat's main 12v feed to the pump, using a multimeter. The prongs of the multimeter wedge in quite securely behind the spade connectors and their plastic covers so there's no uncertainty about the readings that could be blamed on not holding the prongs steadily, but it might be relevant to my readings and the pump's performance.  These are new spade connectors installed with the new pump (the old pump was connected via one spade connector on the positive, and one chocblock connector on the negative for whatever reason who knows; and the copper negative wire looked grey and tarnished. I removed this tarnished bit when putting in the new spade connectors. Connections now feel tight and secure. I can't rule out they might need doing again or a different type of connector though, I'll check them again tomorrow)

 

Measurement 1:

ENGINE OFF

BATTERY VOLTAGE @ SMARTGAUGE 12.6v

 

Voltage at pump (not running) 12.43v

 

Voltage at pump (running with kitchen tap on) Gradually drops to 6.88v before pump cuts out. Pump cuts back in again after a few seconds.

 

Current at pump with 10A multimeter (pump not running): 10.29A

 

Current at pump with 10A multimeter (pump running): 9.4A initially, and pump is running with a lower pitch sound now that the multimeter is across it measuring the current. Current gradually drops to 6.3A before I turned off the tap and pump at the isolation switch, because the pump sounds increasingly low pitched and unhealthy. (However the multimeter is only supposed to take current readings for a maximum of 10 seconds before taking a break so I realised later, and I exceeded this. The multimeter may have been impeding current or voltage at the pump, as the pump didn't run at a low pitch and didn't noticeably slow down before, for example in the video I posted a few days ago? Is it possible that the multimeter is affecting the pump's performance? Anyway, I was mainly  interested in measuring the current surge)

 

Incidentally, there was no juddering of the pump during this test. But it doesn't happen every time anyway.

----------

Measurement 2:

ENGINE RUNNING AND HAS BEEN FOR AN HOUR

BATTERY VOLTAGE @ SMARTGAUGE 13.85v

 

Voltage at pump (not running) 13.59v

 

Voltage at pump (running with kitchen tap on) Gradually drops to 7.95v before cutting out.

 

Current at pump with 10A multimeter (pump not running) 10.29A

 

Current at pump with 10A multimeter (pump running) 9.84A initially. Pump is running with a lower pitch now the multimeter is across it measuring the current. Current reading gradually drops to 6.5A before I turned off the tap and pump at the isolation switch because the pump sounds increasingly slow and unhealthy.

------

This is where it got scary.

Aborted measurement 3:

I found what I believe to be the wiring to the isolation switch for the pump. I'm going just by the location of the junction in the main 12v cable leading to the pump, and the fact that the positive cable is bridged by twin-core thin white cable (I've seen thin white cable near the isolation switch before). It's attached across the thick red positive 12v cable via chocblock. I bipass the switch by detaching one of the white cables and connecting the two halves of the thick red cable, positive to positive, through the chocblock - essentially directly connecting the pump to the original 12v electrical supply omitting any isolation switch. (Or so I thought) As I got up to turn a tap on I could smell smouldering plastic and my head torch picked up a tiny glimpse of what seemed to be smoke down near the pump wiring. I quickly turned things off, detached the multimeter and put the red and white "switch" cabling back as it was. The burning smell went away. The pump hadn't yet turned on (I now suspect this heat was from the 10A multimeter lead because it's unfused when measuring at 10A, but at the time I couldn't be sure the smoke hadn't come from other wiring)

-------------

Measurement 4 - half aborted.

While tentatively investigating where each cable leads, after the last scary moment, I noticed one of the white isolation switch cables (not the one I detached and reattached earlier) was only loosely fitted in the chocblock. I thought that maybe a loose connection here might have been the problem with the pump all along. So I tightened it up and turned on the multimeter - it showed a H symbol and a minus sign. I can't find the H symbol mentioned in the multimeter manual (common sense might have told me it might stand for "Hot" but that didn't cross my mind until...). 🤔 As there wasn't any smoke or smell, I turned on the isolation switch and a kitchen tap. The H symbol and the minus sign disappeared, which I thought was probably good, and the pump ran as last time and with similar voltage readings: 

 

ENGINE RUNNING AND HAS BEEN FOR A FEW HOURS

BATTERY VOLTAGE @ SMARTGAUGE 13.85v

 

Voltage at pump (not running) 13.72v

 

Voltage at pump (running with kitchen tap on) 9.42v initially and gradually drops to 8.28v before cutting out.

 

Current at pump with 10A multimeter (pump not running) 10.9A and dropping quite quickly despite nothing other than the multimeter (and possibly the isolation switch, I forgot to note it) being turned on yet. In measurements 1 and 2, the current didn't drop until the pump motor kicked in! But here it was going down on its own - multimeter unhappy increasing resistance maybe? I hadn't even turned the tap on yet. I then smelled hot plastic, the positive multimeter cable was hot to touch, and so I detached the multimeter cables from the meter, turned off the pump's isolation switch and haven't attempted to run the pump since. 

-----------

So.... I've not burned the place down but won't be repeating that particular experiment. I'm losing the daylight and head torch alone isn't enough to clearly see the cables in order to problem-solve down there. So I'll come back to it tomorrow as it's been made safe for tonight. 

 

I've now got lots of questions to ponder...

Possible reasons for the heat/smoke? Most likely *I think* : Having scoured the multimeter manual again I'm guessing it was on current reading mode for too long. Hence feeling heat in the multimeter positive cable. Hopefully that's all it was.

 

Despite doing my best to trace the other electrical cables, I can't rule out having ballsed something up around the chocblock connections between measurement 2 and measurement 3. Maybe the thin white twin cable leads to something other than the pump isolation switch? I've not seen anything else that has cable like that but as it disappears into the built-in furniture and behind a wall, who knows? 🤔 Logic is telling me that the way it bridges the main 12v positive only, that it's got to be for a switch. But this is a Black Prince boat that's had previous private owners too - that adds the element of surprise and mucho chocblock to the wiring 😃

 

Maybe the 10A multimeter isn't high enough rated for the new pump? That's a worry because supposedly the pump should be safe on my boat's wiring which was for the old 10A fused pump 👀 It would be nice if I knew how to check the gauge of the 12v cable without having to purchase more tools. We guessed at the gauge here by appearance in a photo only which isn't ideal.

 

Maybe the boat's main 12v cable really is too thin for the new pump (although the pump motor wasn't running when the smoke appeared) and the Jabsco boys were sure it wouldn't have a start-up surge that's anywhere near 10A.

 

Maybe at the chocblock I connected two things that should not have been connected? 

 

As I never detached the multimeter prongs from the spade connectors maybe I did something wrong at the terminals of the multimeter itself - I double checked the terminals at the meter afterward and couldn't see anything wrong but I did turn the dial without remembering to unplug the terminals first. And that's not great.

 

Maybe a previous owner replaced the 10A fuse in the main boat electrics for the water pump with something higher rated and the heat and smoke was due to the fuse at the other end of the boat not blowing if it should have done? I hope not but will endeavour to find out (big job as fuses aren't labelled and aren't easy to access)

 

Too many maybes. I'll need to follow cables along when I have daylight again to see what leads where, and rule out any cock ups other than leaving the multimeter attached too long. 🤔

 

In the meantime, I'll take

measurements 1 and/or 2 again tomorrow, if all seems safe, and if the multimeter hasn't died due to my cooking it. But I'll only do it once I've triple-checked connections and what cable leads where, in daylight hours, and without measuring current again - just volts. I'm nervous of bypassing the isolation switch again because of the smoke last time. But if the smoke was only from the multimeter, then it might be safe to do. And that would rule in or out any issues being caused by the pump's isolation switch and its thin cables. Does this sound like the way to progress?

 

(I've not heard back from Jabsco yet. But it'll be helpful to be armed with electrics data that corresponds to the pump's performance, when I speak to them anyway)

 

Phew! 

Edited by BlueStringPudding
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If you put the meter cable into the amp socket then even if the meter is set to volts and the cables connected to the wiring you woudl get smoke from the meter and the amp scale may no longer be reliable or even working. This is a very common mistake and is the reason why all the training meter had a 5 amp fuse fitted into the lead. Some meters have a fuse inside but often its only for the  mA scale.

 

The way the voltage drops looks more like a flat battery to me although as the motor slows as the pressure rises the current would increase so any volt drop on the wiring would also increase. However The initial voltage readings on each test suggests the batteries are OK, especially the with engine running ones.

 

It may be easier/quicker to run a new cable to the pump of more than adequate size and replace any switches or at least run a test cable from battery to pump and see what happens.

  • Greenie 1
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