Fimco sprayer - 12v 2.1 gpm flojet pump motor quit

Hi. I have a 25 gal. Fimco sprayer with a 12v 2.1 gpm flojet pump that quit working last night. I filled it with water this weekend and sprayed for a while and it worked fine. Then I added some roundup last night. It sprayed for a few minutes with the hand wand just fine. Had the return valve adjusted so it would put out about 50 psi when the hand wand wasn't being used.

Then nothing came out. If I closed the hand wand and let it build pressure for a couple seconds then it had enough pressure to spray for a couple seconds before dwindling down to nothing. I sprayed for a few minutes by opening and closing the hand wand until the pump motor just quit all together.

I have 12 volts going into pump motor with the switch off but when I turn on/flip the switch on the end of the pump, then the voltage reading goes to 0. The motor doesn't spin and it wasn't hot. With pump motor unpluged I get a 0 reading for resistance with the switch off but when I switch it on, I have continuity. The fuse on the end of the pump motor is not blown.

I figure the motor is either locked up or a winding went bad. This evening I will try blowing some air through it and take it apart.

Any ideas before I buy a new one? Thanks.

"I have 12 volts going into pump motor with the switch off but when I turn on/flip the switch on the end of the pump, then the voltage reading goes to 0."

You have a bad connection in the supply wire to the motor. If the motor was actually dead-shorted and dropping the voltage to zero, smoke would leak out of the wiring and/or the motor!

Other possibility (depending upon where you have the(-) probe from the meter connected), is a bad ground.

Thanks Bob. I agree that the voltage going to a dead short should cause something to get hot somewhere in the wiring or the motor which wasn't happening. The motor has about 6" of wire coming out to a plug in dual wire connector. That is where I checked the voltage with the positive and negative on the connector. The battery side of the connector didn't always read voltage and the rubber was partially chewed on by the mice so I replaced it. The motor side of the connector looked OK but maybe it needs replacing as well. Maybe I'll get lucky here.

If you do get it running be sure and rinse it well. Roundup is very hard on those little pumps. BTDT.

The motor probably has an electronic pressure switch that is bad. That's why they run until pressure builds then stop. Then the pump cyccles during use, supposed to save battery and motor. I'd check that as the culprit.

batt have good charge?, the pump, are you using the pump like on r-v's, demand pump, works when no pressure build-up [spraying] and stops when pressure builds-up [stop spraying]. don't know how much pressure/gpm needed. r-v pumps can have 3.0gpm cost around $75...can't expect those small motor to last forever..depending on how old, don't waste good time on a small item and go crazy trying to fix.

I'm going to go look at it now and check that plug in connector. When I checked the voltage after changing the battery side connector I was checking the voltage off the new splice connections and not from the plug in.

This is the old style pump and motor that is not a demand type as I recall. The pressure is regulated by a valve on the return line to the tank. It always ran continuously in the past.

These motors are permanent magnet type.-The glue used to fasten the magnets to the motor housing is not waterproof.You can get new brushes for FloJet motors.No field windings in these motors.

Mine did the same thing last year. Turned out to be a bad pressure switch. Easy to change--cost around $25.00.

Larry

I replaced the connector with no change. Ended up taking the motor part way apart.

After pulling off the end plate with the brushes, I have 12-13 volts at the brushes with the switch on so everything up to the brushes appears to be in good shape. The armature is free and will move the pistons. (it has a gear that runs two pistons back and forth and I could rotate the armature back and forth)(I didn't try to spin it as it had some resistance). I put the juice to it and pushed on the pistons moving the armature and it didn't help.

The commutator or whatever where the brushes ride has 10 copper segments to it. All the segments showed continuity with each other with about 6 or 7 ohms resistance.

Any idea now what is wrong? I'm guessing an armature winding has a dead short although everything I can see from one end looks ok. Thanks.

I'm stumped. Had it all apart. Everything looks good. Cleaned the brushes and commutator. The magnets for stator were ok and I cleaned them. They would cause a little resistance when I turned the rotor. When apart I still have 12 volts at the brushes. When apart I have continuity between all 10 segments of the commutator and there is no short with the metal part of the rotor or main shaft. When I put it together it doesn't want to spin even when I help it.

Nothing interferring with the brushes. With power disconnected I get continuity with about 7 ohms and it fluctuates when I turn the rotor which tells me the brushes are making contact ok.

Just like before I have 12 volts everywhere until I turn on the switch and it goes to 0 but nothing sparks. When I had it apart and getting 12 volts onto the brushes, the switch worked fine so the power circuit seems good until I slike the end cap and brushes onto the commutator.

Any ideas? Thanks.