DC pump not working properly

Hi there folks, I finally got my tiny house plumbing set up but the dang pumps not working! The pump is DC as I will be installing solar eventually. In the meantime, I have a AC/DC 12v inverter to power the pump for now. The output is 8.5 amp on the inverter the pump requires at least 5. I also have it split running to a precision temp propane hot water heater.. that uses the 12v to light. I am wondering if this sounds more like a power issue or an issue with the plumbing? From my experience the pumps sound like they have more power than this and cycle more frequently when pressurizing the lines. Anyway just curious what your first thoughts are when hearing the pump cycle like this. I will do some more troubleshooting and share my findings!

I tried to upload the short video clip but it didn't upload. The pump cycles in a very low hum every few seconds. I don't hear any water moving through the lines.

I checked all of the electrical and it has 12 volts. It's weird how it sounds.. I am beginning to think the pump may be bad..yet it is brand new. Every pump I have heard sounds like *vroooooomp vroooooooomp vroooooooomp* (rather quickly and loud). This one sounds quiet and intermittent...(softly) dunk* (1..2..3) dunk* (1..2..3). I wish I could post a video!. I wonder if it needs primed but either way it doesn't sound like I think it should when it is kicked on 🤔. Open to thoughts on the matter

What is the model? Is the 5 amps the running requirement or the starting requirement? An electric motor takes a lot more amperage to start than to run, and if your power supply (an inverter goes DC to AC by the way, not AC to DC) can't meet the inrush current requirement, it won't start...


Also, if it's not a self priming pump, make sure it's primed.

Thanks for the clarification on the inverter!

The pump is a shurflo 2088-554-144
httpss://www.amazon.com/gp/aw/d/B00C1M6B1C/ref=cm_cr_arp_mb_bdcrb_top?ie=UTF8

I used a transformer to power DC appliances with AC.
https://www.amazon.com/dp/B01MRO3NYU/?coliid=I14V99BOIJM38J&colid=N28T85QX9RXX&psc=1

I grabbed a junker DC water pump that I had and hooked it up and it ran fine so I am pretty sure the new pump is bad. The unfortunate thing is I purchased it 4 years ago and just now installed it to discover it doesn't work. I opened it up and made sure the diaphragm wasn't stuck and it seems to be fine. I think the motor might have been bad. 🤦

I second Nick's concerns about starting current being the issue. The momentary draw can be massive, depending on the motor design. Many motors have a big fat capacitor to help them start. A converter for LED lights may not give enough initial push for this pump.

I would test the pump using a high amperage DC source, like a car battery.

Did you check for voltage on the ground wire?
More of a 12volt car thing,...
If the ground wire has voltage it isn't grounded right.

Was your old test pump of the same kind as the one that isn't working?

The Shurflo is the one I am trying to install. The Flojet worked perfectly well when I hooked it up. Thank you all for your advice on this matter!!

"Recommended slow blow fuse 15 amp"

That indicates what the initial current draw may be for this pump.

I will hook it up to a car battery and see if it's the starting amperage that is the issue. It may be best to just buy an AC pump while hooked to the grid. I was trying to get around that with the transformer since my water heater needs 12v and is located right next to the pump. That and the future solar install.

So I tested the pump on a car battery and it worked perfectly. I also hooked it back up to the system and it worked a few times.. Then eventually it no longer worked and just continued it's hiccup. I haven't yet installed the ground as I didn't think this would effect the power test? Also, I read it MUST have a 15 amp slow blow fuse. I had installed a 15 amp auto fuse inline but didn't realize it specified it needed to be a slow blow fuse. I didn't think either of these issues would effect the power test but perhaps it's more important than I realized? I feel like it's the transformer just doesn't have the appropriate amperage to kick the pump on and I should just purchase an AC pump until I get the solar installed.

On high power car stereos they use capacitors to handle the surges.
It basically acts like a battery.
Charging while not in use and has the power available when the voltage drops from a load.

A "slow blow" fuse is nothing fancy. It just tolerates some extra current during startup before it pops.

I think you're on the right track: your converter can't punch out enough startup amps for this particular motor/pump. Other pumps may work just fine, though. And now you know what to look for.

I hooked it up directly to the transformer and it worked but not everytime so I will just buy an AC pump for now and keep the other on stand by. I'll just use the transformer to power the lighting requirements for the propane water heater.

It was definitely worthwhile learning some troubleshooting and hearing everyone's inputs and suggestions! You all rock here on permies! I am grateful for this knowledgeable and humble community! Thank you all!