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Shurflo faucet switch failure - repaired
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jimf909 Premium Member
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PostPosted: Fri Aug 10, 2018 4:21 pm    Post subject: Shurflo faucet switch failure - repaired Reply with quote

Hi All,

Symptom: Westy camper fresh water pump works intermittently.
Diagnosis: Shurflo faucet switch completes the circuit and provides voltage but does not allow enough current to run the pump.
Tests:
- Removed Shurflo from the circuit and the pump runs 100% of the time when completing the circuit by jumping the yellow wires that connect to the faucet switch.
- Removed pump from the van and bench tested with a 12v battery and it ran 100% of the time.
- Replaced pump in the van, included the Shurflo in the circuit and the pump worked intermittently (about 20% of the time).
- Put a voltmeter at the pump contacts, turned on the Shurflo and measured battery voltage but the pump wouldn't spin.
- Likewise with a lamp: connected the water pump wires to a 12v lamp and measured battery voltage with the Shurflo switch turned on but the lamp wouldn't light up. Bypassed the Shurflo and the lamp lit up.

No matter how I sliced it, the Shurflo would send volts but apparently not enough current to power anything.

Background: The Shurflo faucet was already replaced under warranty last Fall. I dissected that pump and the switch contacts were blackened (see first photo below). That Shurflo exhibited the same symptoms.

I called Shurflo and the tech suggested that the pump may be drawing too much current. The Shurflo is rated for 3 amps but I measure .393 amps when running the pump through the van's circuit.

Questions
- Has anyone else experienced this Shurflo failure?
- If I'm measuring current flow correctly, does anyone have any ideas on what might be causing this?
- Any other comments or questions?

Blackened spot on the contact. I'm assuming this is the cause of the problem:
Image may have been reduced in size. Click image to view fullscreen.


Measuring .393 amps of current draw:
Image may have been reduced in size. Click image to view fullscreen.


Product label:
Image may have been reduced in size. Click image to view fullscreen.


Thanks.
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Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).


Last edited by jimf909 on Sun Aug 12, 2018 8:43 am; edited 1 time in total
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fxr
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PostPosted: Fri Aug 10, 2018 4:50 pm    Post subject: Re: Sureflo current flow failure? Reply with quote

The Shurflow switch seems not to like passing the current the pump needs.

Easy solution - add a relay to power the pump, energised (with very low current) from the Shurflow switch.
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davevickery
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PostPosted: Fri Aug 10, 2018 6:55 pm    Post subject: Re: Sureflo current flow failure? Reply with quote

Yep, sounds like the wiring or contacts in the switch are loose.. if you don’t feel like taking it apart more you could also just wire in a different switch, maybe the foot one or a toggle switch.

I have the faucet that eurocampers.com sells, kind of a smaller version of yours and it has been good and was less money if you are looking for a replacement.
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Farf
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PostPosted: Fri Aug 10, 2018 8:02 pm    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

That's a pretty high no load current on the pump. What does it draw if you connect it directly to the battery taking the van wiring and switch out of the equation?
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PostPosted: Fri Aug 10, 2018 10:13 pm    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

Farf wrote:
That's a pretty high no load current on the pump. What does it draw if you connect it directly to the battery taking the van wiring and switch out of the equation?


No load...d’oh...

The same no load divorced from the van = about the same amps @ .4 (different battery)...

Image may have been reduced in size. Click image to view fullscreen.


Adding a load jumps the amps to 2.6 and that’s absent the 18” lift and 48” hose. All of a sudden we’re nearing the limit of the Sureflo switch.

Does 2.6 amps for this little pump seem high? I’m wondering if a bad pump increased current load and killed both Sureflo switches.

Image may have been reduced in size. Click image to view fullscreen.


davevickery wrote:
Yep, sounds like the wiring or contacts in the switch are loose.. if you don’t feel like taking it apart more you could also just wire in a different switch, maybe the foot one or a toggle switch.



Yep, the next step is to wire in an old time car horn button to use as a foot switch. Although I may need to replace the pump as it may be old and drawing too much current.
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Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
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PostPosted: Sat Aug 11, 2018 7:04 am    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

nearly 3 amps sounds fine for a water pump. the switch contacts are under-rated, tho properly labeled with their rating! adding a relay or footswitch are good ideas.

OR you could try a non polar capacitor in parallel across the motor. this can be done up near the switch wires, don't have the capacitor in the water. the value is a bit hit or miss to figure out but i'd start with a 22uf, 100volt one and see if that clears the problem. the capacitor will reduce some arcing when the switch contact is opened.

clean the switch contacts up with a points file (a voltage regulator file would be even better as they are finer) and rinse with Caig DeOxit, miracle in a can.

https://www.allelectronics.com/item/nc-22/22uf-100v-non-polar-capacitor/1.html
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PostPosted: Sat Aug 11, 2018 8:36 am    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

Thanks for the suggestions!

Have any others experienced this issue? I love the adjustable flow of the Sureflo but losing two switches in a year is a bit frustrating.
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- Jim

Abscate wrote:
Do not get killed, do not kill others.


Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
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PostPosted: Sat Aug 11, 2018 8:57 am    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

I just checked mine. It is a replacement pump, same submersible style but different brand and it uses 2.4 amps running. Not much difference running on low or high flow. When I first connect the test leads it spikes at 2.6 amps.
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PostPosted: Sat Aug 11, 2018 9:20 am    Post subject: Re: Shurflo faucet current flow failure? Reply with quote

^^^ That’s very helpful. Thanks. I’ll reinstall the pump today and check current while pumping water through the system.
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- Jim

Abscate wrote:
Do not get killed, do not kill others.


Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
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PostPosted: Sun Aug 12, 2018 9:01 am    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Just as I was about to bypass the Sureflo faucet switch with a separate foot switch I decided to attempt a repair. The tech at Sureflo said the faucet can’t be repaired and should be tossed if it doesn’t work. However, having dissected the previous Shurflo that failed last year I had some idea on how to take it apart:

Separate the knob from the faucet with a solid whack on a screwdriver positioned here. Remember, this is designed to NOT come apart. The first faucet I disassembled ended up looking much worse.
Image may have been reduced in size. Click image to view fullscreen.


Clean the blackened contacts...
Image may have been reduced in size. Click image to view fullscreen.


File down the knob retaining nubs to make future disassembly a hand-to-knob, no tools required affair...
Image may have been reduced in size. Click image to view fullscreen.


Reassemble. Add an SAE plug to the faucet and van wiring harness to make future disassembly easy.
Image may have been reduced in size. Click image to view fullscreen.


As to why two Sureflo faucets failed for me in less than a year:
- It’s not current draw while pumping water through the system, I read about 2.5 amps, similar to davevickery and w/in the switch’s 3 amp rating.
- My best guess is that a piece of the pump impeller broke and jammed the pump increasing current load (the impeller appears to be missing a part of itself). If it was a faulty Sureflo product I’m guessing we’d hear about more failures.
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- Jim

Abscate wrote:
Do not get killed, do not kill others.


Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).


Last edited by jimf909 on Sun Aug 12, 2018 4:32 pm; edited 1 time in total
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PostPosted: Sun Aug 12, 2018 10:01 am    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

i don't see any evidence of over current.... the plastic holding the contacts is not melted nor discolored. but there is carbon evidence of arcing... this is likely a result of 2 design flaws. a) the contact material may not be high quality and carbonize easily, and b) the switch design is such that the contacts are slowly made and broken by the knob turn, in other words no snap action to quickly close the contacts. this contributes to arcing also.

so i did some reading and suggest the following to suppress arcing at the contacts. i would install a parallel circuit of a resistor and capacitor across the switch contacts per the diagram below:

Image may have been reduced in size. Click image to view fullscreen.


the value of the resistor and cap can be determined by the no-math rule of 1 mF per amp and 0.5-1 ohms per volt. so, 3uf cap (rated 50v is fine) and 6-12 ohm resistor (1/2 watt). this should reduce arcing at the contacts.
[/img]
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PostPosted: Sun Aug 12, 2018 4:14 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Thanks for the helpful diagnosis and proposed solution. I’ve been pretty much shooting in the dark as to the cause of this.

The switch does have a spring that snaps the contact open and closed, it’s just not installed in the photo above. Regardless, the contact is still failing, possibly due to arcing.

I’m perplexed that I haven’t read of similar failures here given that I’ve had two faucet switches fail in about two years. Mostly, posts mention reliability such as the post below:

crazyvwvanman wrote:
I think we have 7 vans still in the family with Surflo faucets. Had several more in vans that are now passed on to new owners. Never had an issue with any of them afaik. I'd guess we have something like 100 years of Shurflo faucet ownership. I have more than 50 years myself.

Mark


https://www.thesamba.com/vw/forum/viewtopic.php?t=675389&highlight=shurflo

The good news is that I can now easily remove the knob to clean the contacts if needed.
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Abscate wrote:
Do not get killed, do not kill others.


Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
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PostPosted: Mon Aug 13, 2018 1:01 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Switching grounds on circuits instead of the power side will help to alleviate arching at the switch. Not always convenient to do.
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PostPosted: Mon Aug 13, 2018 2:15 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

MarkWard wrote:
Switching grounds on circuits instead of the power side will help to alleviate arching at the switch.


Wired mine in exactly this way after I saw this thread Laughing

Well that and fuel pumps operate this way so it just made more sense to me to do so.
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PostPosted: Mon Aug 13, 2018 5:45 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Switching at the ground side instead of the +ve side makes no difference to the arcing. The arcing occurs because there's a reactive part in the circuit (in this case the inductance of the pump motor) and when the current is stopped suddenly a high voltage is induced across the contacts.

That resistance/capacitor circuit shown above will alleviate this, whichever way the circuit is switched. When the contacts separate, the instantaneous high voltage will try to charge the capacitor instead of arcing across the contacts. The total charge available is tiny, so any high voltage across the contacts is quenched very effectively.

It's an electronic version of a shock absorber if you will...
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PostPosted: Sat Mar 20, 2021 4:21 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

FWIW I also have this issue and have to pop the knob off and run a piece of sandpaper in between the contacts pretty often. It's rather annoying. I haven't tried anything else from this thread but thanks to the OP for figuring it out as far as this.
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PostPosted: Sat Mar 20, 2021 9:30 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

FWIW, I haven't had any problems in 2 1/2 years since. Same faucet, same pump. I still don't have a smoking gun but the broken impeller jamming the pump and increasing the load is my best guess. Emphasis on guess.
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Abscate wrote:
Do not get killed, do not kill others.


Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.

Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro).
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PostPosted: Sun Mar 21, 2021 8:42 am    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Forum;

A bit late to this thread, but I needed to chime in with a couple of points...

Dan; ...compliments on the good info!...especially the Slow-Make/Slow-Break switch action explanation...this is typically an inexpensive electro-mechanical solution with direct action from person's input to contact (and not adding an over-center linkage with spring, or other such more expensive complications)...I do wonder why you recommend an RC Snubber network over a flyback diode, which would serve the same function without necessitating a bit of a design effort...please explain your reasoning here...just as a point of interest...the ancient hydraulic brake pressure sensing brake light switch of vintage Volvos (and I expect older VWs also) has a moving contact actuated by brake sys pressure (and also no FM/FB mech in sight), so you can guess what often happens here...especially if you apply brakes gently and not like someone who has just seen a suicidal deer at 12 o/clock high! I highly recommend replacing this type of brake light sw with a pedal position sensing switch...on VWs also!...if interested, see: https://www.sw-em.com/hydraulic%20brake%20light%20switches%20notes.htm

Mark; ...as already pointed out, low side switching doesn't buy you relief from switch contact arcing...because it doesn't matter if switch is in the low or power side, it must still break the load current, which in this case is inductive because of the motor...I just wanted to explain it in a way that might help you understand it well...

Cheers
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PostPosted: Sun Mar 21, 2021 12:05 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Ronzo_volvo_guy wrote:
Dan; ...compliments on the good info!...especially the Slow-Make/Slow-Break switch action explanation...this is typically an inexpensive electro-mechanical solution with direct action from person's input to contact (and not adding an over-center linkage with spring, or other such more expensive complications)...I do wonder why you recommend an RC Snubber network over a flyback diode, which would serve the same function without necessitating a bit of a design effort...please explain your reasoning here...


that's a great question! to MY understanding, a flyback diode protects sensitive circuitry from the EMF kickback voltage spike that could damage sensitive circuitry, which in water pump wiring there is none. HOWEVER, it would likely work and actually is used in conjunction with the RC network sometimes. here's a great article on DC switch arcing:
https://www.jameco.com/Jameco/content/How-to-reduce-emi-voltage-spiking-and-arcing.html

and apparently that water pump switch does have a snap action to it via a spring that was not shown in the picture.
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Past projects can be found at--
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PostPosted: Sun Mar 21, 2021 1:10 pm    Post subject: Re: Shurflo faucet switch failure - repaired Reply with quote

Dan;

"a flyback diode protects sensitive circuitry from the EMF kickback voltage spike that could damage sensitive circuitry"

...I'd like to rephrase if I may...: A flyback diode quenches the back EMF spike, thereby minimizing the voltage and energy the controlling switch is subjected to (be it a sensitive transistor or a brute force contact!). What I'm trying to point out is that the flyback diode will therefore also protect and minimize contact erosion! I can also point out that especially with a DC motor as a load, as soon as the current is broken, the motor will go into regen mode and try to use the energy of intertia, turned back into electricity, to keep that arc going...even worse than just an inductive load!

Just try with diode it next time you have a DCmotor on the bench...it's just important to size the diode right for PIV plus total energy...

Cheers

Edit: ...after looking at the linked page, my suggestion is shown in Fig. 6.
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