12V pump help, please!


I have been having endless problems with the pumps attached to my tank system. I have a 165 gallon tank with two Flojet 12 volt pumps. The pumps are 2.0 GPM, 100 PSI. I have recently added a motor controller to slow down the pumps. I am running 3/16" ID pole hose straight out of the pump, generally about 200 feet of hose, sometimes an extra 50-100 feet.

I have used this setup for 5 years now, with 4 or 5 different pumps (always the same Flojet model & specs.) I had to replace both pumps over the winter because I allowed them to freeze and they broke. Ever since, I have had trouble with cycling due to back-pressure. The only way I could get the pumps to stop cycling was to adjust the pressure switch.

My pumps are running hotter than I’ve ever noticed before, even while running slower with the motor controller running at about 2/3 speed. The pumps will shut-down for a couple of minutes when they get hot.

I am looking for any help to solve this. I have never had any issues with this setup for 5 years and now, all-of-a-sudden, I am having nothing but problems. I just need them to work so I don’t worry about when they will fail. It’s busy and I don’t have time for this.



What flow controller are you using? I have used the the WCR model (re-branded RHG) for 5 years and a Shurflo 60psi 1.8 pump with no issues. If the motor is heating up, the pressure switch is not opening the circuit when you shut your water off.


I use a 1.8 gpm 100 psi Shurflo. Its worked great so far, and it has an auto shut off once it reaches its pressure level, no cycling needed. You can’t let it freeze though, just like your flojets.


What size off hose are you using out of the pump?


Idk. I’m stumped. What really has me amazed is the fact that you didn’t have cycling and overheating issues with this setup for years. 3/16” pole hose is super restrictive.

Maybe they’re now setting the pressure switch lower from the factory?

I would bump up to at least 1/4” air hose, though 3/8” would be ideal for the 200’ section. Then have a quick connect at the end to connect 50’ or 100’ of 3/16” pole hose.

Something else that just occurred to me:
Was there any water in the suction lines when the pumps froze? That could have introduced small leaks that will let in air and prevent the pumps from operating correctly.


Thanks for your thoughts, Alex. The suction lines are sound - no air leaking in.

A lot of people have been surprised that I’ve run the small line like that, and I’m learning why. I know 3 other W/C’s within a couple of hours of me that are also using the 3/16" line, with no problems.

What pump, hose, etc. are you running these days?


I’m using this flow controller:

I’m not sure what you mean when you say “the pressure switch is not opening the circuit when you shut your water off.” Can you elaborate? I have adjusted the pressure switch down, to make the pump stop cycling while running. This also makes the pump run a few seconds longer when I close my valve at the pole, as the adjustment makes it less sensitive to pressure.


Air leak somewhere


No air leaks. I’ve checked.


I’ve got 300’ of 1/4” air hose, and about 15’ of pole hose (I run the air hose right up the pole)

I’m running a “High Flo” 2.1gpm 60psi pump from Tractor Supply. I’ve got a cheap $15 PWM from Amazon for my controller. Most of the time it’s maxed out, unless I’m on a job that’s more susceptible to splashback issues. Then it’s around 60-70%. Either way, I haven’t had cycling or overheating with my setup. And I run hot water through the pump on a fairly regular basis.

I’m still suspicious of your suction lines. Small leaks can be really hard to detect on suction hoses. I would just run new ones, with as few connections as possible. Haven’t really got anything to lose from it, at this point.


Since the pump does not have a bypass the flow controller is programed at 20-30sec intervals that “checks” the pressure switch when the water is shut-off. It makes a faint sound. I use 3/16 ID directly off the pump and it generates very little heat. It’s got to be an issue when you have your water turned off at your pole that creates the heat? My flow controller has a calibration point so it does not create a “hammering effect” on the pump during operation.


If you have two pumps running at 2/3 speed with each drawing 4 - 5 amps each ( 8 to 10 amps combined) This would make calibration difficult because the controller is trying to manage two pumps and lines with different pressure and current draw. The line at lower height will get most of the pressure and water as water will take the easiest route. Also reducing or stopping flow on either line would mean the controller would DE both pumps not just the one with the tap off. This varying pressure and current draw will also make the cycling described more likely. If he is running two pumps form one controller. My advice would be buy a second controller and have one for each pump.


In terms of pump temperature The pumps after being run for an hour plus could reach 60 - 140F. If the thermal protection on the pump is shutting it must be at the top end of that range. Not sure why this would be, Are the pump housed in a metal Box ?? or do they have air circulating around them


Hi John. Thanks for your input. The controller box is a dual controller - a different controller for each pump. However, only one controller has been connected so far - I haven’t had time to re-wire both. Only one pump is controlled so far. This controller does not offer any sort of calibration. It’s just a straight motor-controller.

I have been surprised to note that even when the pump speed is dialed down to 70%, the pump still gets to the same temperature. It runs noticeably slower, but doesn’t run cooler. Pump A is on the controller, Pump B is straight to the battery. Both pumps are at the same temperature after 45 minutes of operation. Maybe that is normal, I don’t know. (I have an IR thermometer to check the temps.)

Both pumps got up to 145-149 degrees, but neither one shut off, last night when I tested them. Neither pump is enclosed in a box - I believe there is sufficient air around them. One pump was pushing water through 150’ of 3/16’ hose, the other through 100’ of 3/8" hose, then reduced to 50’ of 3/16" pole hose. Both got to the same temps. The only times the pump has shut off was when it was connected to the flow controller.


Hi Tony. The controller pictured is reliant on the pump pressure switch opening to stop the pump. If the pump PS has been set to max the pump is being driven quite hard. There will be a high conductive load on the pressure switch as it opens as the pump draws more current to try overcome the restriction, this can cause arching across the contacts which is contributing to the extra heat in the pump. This heat will will also likely mean the pump is drawing more current which is then turned into heat, As amps are used to create heat rather than push water the pump compensates by drawing more current. Some of this also then generates heat.

The smaller ID hose line may also create some issues as the hose itself becomes a restriction as previous comments a larger ID hose will help. Once the hose has reached its maximum carrying capacity forcing more water into the line increases the resistance of the hose wall and can increases pressure, The cycling pressure switch mentioned could be a sign that the hose capacity is being exceeded. when the pressure switch opens some of the pressure bleeds away allowing the switch to close, Pressure builds up and the PS cycles.

One other alternative would be to reduce the flow rates and try find the maximum water volume the hose can carry. This will reduce the pressure in the line, reduce the pump PS cycling and the pump will run cooler

Alternatively have a chat with John re a V11 Dual. These allow you to calibrate each pump individually and have a Dead end calibration, This means the pump is switched well before the pump PS is activated. There is then less load on the pump motor. The V11 has heat syncs and passes unused energy back to the battery. This helps keep the pump cooler. The V11 has a number of features and functions designed to manage the pump in an efficient way


Hi Ian. Thanks for taking the time for your response. If I knew that the V11 controller would work, I’d order it right away. But, I’m reluctant to make another significant purchase without knowing whether it will actually work or not. I purchased a different pump / controller combination after being assured that it would work on my setup with 3/16" ID line. It would not. Their pump cycled like the others, despite all calibration attempts and help from their support line. Their possible solution was to bypass the pressure switch completely, although he told me he didn’t know if that would damage the pump in the long-run, which was not a good solution, so I returned it.

There is little consistent, useful info out here for the systems we are using, so I appreciate your time on this. One pump expert explained some of the science of pumps to me, and it was very informative, but then told me that my setup only worked for the previous 5 years because “Somehow I got lucky”. If it worked, there is a reason why. If it doesn’t, there is a reason too. Thanks.


Have you replumbed the supply lines yet? In terms of troubleshooting, that’s the simplest next step to take. Even if you’re 99% sure that isn’t the issue, it’s still worth trying because of how simple it is to do.


Hi Tony.

I can understand your reluctance, particularly as the system has worked for a good time before the pump froze. The question of what has changed comes sharply into focus. Has the system always had a 2GPM pump ? or was it smaller previously. The issue may just be the pump/hose combo is creating to much pressure.

My gut feel is that the hose ID is to small for the water volume being generated. the 3/16 is almost 5mm.
Generally the UK/EU systems will run a 1.1GPM pump into an 8mm (1/2 inch) or 6mm (1/4) hose pump and reel then use a 6mm or 4mm ID on the pole hose. In parts of the EU some will even run 10mm or 12mm (3/4) on the reel.

The issue may just be the 2GPM pump is overwhelming the 3/16 hose, running at 70% the pump is trying to push around 1.4GPM into the hose. If this exceeds what the hose can carry, the hose its self becomes a restriction. We then get turbulent flow in the hose and a pressure build up that activates the pressure switch.

Finding a way to balance pressure and the required flow volume may just need a little trial and error. One suggestion would be to use a larger ID hose between the pump and reel as this would reduce the pressure at the pump outlet.

If the 2GPM is a larger volume pump than has been on the system before running at a lower flow rate would also reduce the pressure in the line. It is likely that at say 50% you will get a very similar volume of water when compared to running a 1.1GPM at 70 or 80%


I’ve always used the same model of pump - 2.0 GPM at 100 PSI. I’ve never had an issue until this year when I replace two frozen pumps. The plumbing is the same.


The V11 can run with or without the pump pressure switch in line, and will run the pump down to 4mm pole hose, but as above the hose between the pump and reel and reel hose would likely be a larger ID. Having the pump PS bypassed is not an issue medium term as the V11 will Dead End the pump on flow being turned off. Longer term there may be some slight increase in strain on the motor, how much strain is dependant on how hard the pump is running together with system pressure. The V11 have an over current protection, so in the vent the pump draws higher current than expected the controller will shut it down, That level is around 8 - 9amps. So if the Dead end does not stop the pump which it should well before that level of amps is reached, The V11 has an additional fail safe.

So why calibrate the controller to a pump?

What we are doing is telling the control what the maximum pressure the system normally operates at. To get a good flow at the brush head the system is probably running between 40 - 70 PSI. So the control knows that the normal max level is for example 70 PSI. When the water flow stops the pump will attempt to push against the restriction increasing the pressure above 70 PSI the pump sees this sudden rise and stops the pump. This is what we refer to as DEAD END (DE).
When flow is stopped EG the pole tap is turned off. Two things happen

  1. Pressure builds up in the line
  2. Current draw by the pump spikes
    In normal operation the Pump will draw around 3 – 5 amps with system PSI stable as the system is in open flow. Stopping flow means the pump draws a lot of current very quickly and the system pressure rapidly builds. As above the control see,s this sudden change and stops the pump DE
    During this DE (flow stopped period) the controller retests the pressure at the pump every three seconds.
    During the DE retest the controller will briefly pulse the pump for a fraction of a second some operators will hear the pump blip. The Controller is designed to carry out this test but importantly it will not allow pressure in the system to build any higher.
    When the restriction is removed the pressure falls back below the 70PSI maximum and the controller restarts the pump at the preset flow.
    The control is designed to stop the pump before the pump pressure switch activates where the water flow has been stopped. A pump pressure switch may activate at 110PSI give or take (based on 100 PSI pump)