Water pump problems

[fishforfunman]

I have a Flojet water pump that works perfectly until my battery gets below 12.65 volts (works fine on shore power) and then it can't get up to pressure and will run for minutes until it finally shuts off. I called Flojet and they walked me through the usual things, no leaks etc. I open all faucets to remove trapped air. They sent me a new pump and the problem persists. I even have gone through the trouble of replacing all or the flex tubing with 3/8 instead of the 1/2 tubing since it didn't fit the 3/8 PEX barbs tightly at the suggestion of an RV mechanic. I have notice that if I put the water heater on winter bypass that the pump works slightly better. I have released the pressure relief valve to see if that would release air. Flowjet claims there are no adjustments on its pumps like on Sureflo even though there are similar screws on the pump. Any ideas out there, we have resorted to turning off the pump main switch to stop the pump when on battery power.

[Mr Havercamp]

Originally Posted by fishforfunman

I have a Flojet water pump that works perfectly until my battery gets below 12.65 volts (works fine on shore power) and then it can't get up to pressure and will run for minutes until it finally shuts off. I called Flojet and they walked me through the usual things, no leaks etc. I open all faucets to remove trapped air. They sent me a new pump and the problem persists. I even have gone through the trouble of replacing all or the flex tubing with 3/8 instead of the 1/2 tubing since it didn't fit the 3/8 PEX barbs tightly at the suggestion of an RV mechanic. I have notice that if I put the water heater on winter bypass that the pump works slightly better. I have released the pressure relief valve to see if that would release air. Flowjet claims there are no adjustments on its pumps like on Sureflo even though there are similar screws on the pump. Any ideas out there, we have resorted to turning off the pump main switch to stop the pump when on battery power.

I'd try replacing the entire suction line, or tightening up all the fittings on the suction line. It could be sucking just a little air and at 100% full battery power the pump has barely enough oooomph to overcome it, but at anything lower it can't. It doesn't take much of a leak in the suction line to cause issues. I think you have ruled out its the pump itself.

[AquaMan]

Possibly check wiring. May have a loose connection that is causing a voltage/amperage drop when on battery only. Check amperage draw when on shore and battery power, and compare.

[jeff64]

Since you stated that it "seems to be" better on shore power than battery and you have a new pump, I would: Get inexpensive VOM if you don't have one
1. Check out the condition of your battery and it's ability to hold a charge and cable connections.
2. Check the voltage available at your pump and compare it to what you have at the battery terminals. I would hope they are the same or within .2
3. Start with the easiest and most accessable things first at one end of the circuit or another.
4. Renew all your ground connections at the frame. Wire brush and use dielectric grease. Check and renew any obvious + connections on the underside and cut off sw.

[fishforfunman]

I checked amperage. 5.3 on battery power and 5.40 on shore power. Batteries are new but had this problems with the old and new. If I had a leak on the suction end, wouldn't I notice a leak somewhere? I will do some more investigation on wiring on the battery end. Thanks for the responses.

[fishforfunman]

In May I posted a problem I was having for a long period of time. In short, my water pump (Flo Jet) would not stop running after the battery dropped a few tenths of a volt. After spending much money trying to resolve the problem (I was told bad batteries, bad hoses,bad converters etc), I finally found a local rv repairman that did the fix. In my original post, I mentioned that the Flo Jet service man said there is no way to adjust the pumps and sent me a new pump. The new one was worse. What my repairman did was adjust the pump with an allen wrench at the set screw on the front of the pump, much like Shurflo suggest adjusting their pumps. Wa La!, now my pump stops crisply after each use even as the battery drops in voltage. I'm going to write a letter to Flo Jet.

[Mr. Dan]

OP posted his resolution in a new thread. The site team has merged the threads to keep it all in one place and easier to follow.

[Bama Rambler]

That's very interesting.
If the pump is adjustable, I wonder why they wouldn't tell you how to adjust it.