Irrigation pump cycles fast then slow then trips breaker.

[brb649]

I have an older 1 HP General Electric water pump that doesn't use a pressure tank and no longer works properly. It draws water from our lake and has worked fine until recently. The problem I'm getting is that the pump appears to be surging (runs at normal speed for a few minutes then slows down then cycles through this scenario for a few times then trips the breaker). I've tried everything I can think of to fix the situation with no success at all. For example I replaced the foot valve, replaced the zone valves, verified and confirmed the start relay box works and has power going in and out, replaced the transformer for the timer controller, swapped out the timer control unit, replaced the fuse and 9v battery on the timer control unit, replaced the capacitor on the pump, inspected the impeller which looks good, took the pump to repair specialists for testing (they said there is nothing wrong with it and that it has lots of power) but it still doesn't work properly. I'm at my wits end. Help please!

 

[Reach4]

Measure the current through one of the hot wires, and compare that with the expected current. Measure when things are good, and when things are going bad.

 

[Sponsor]

 

[WorthFlorida]

Try changing the circuit breaker. Is it 240v or 120v? Is the pump inside or out near the lake with a long electrical run? Is it in conduit or buried UF cable? If it is buried with cable could have been hit or a something chewed it and you have intermittent short.

 

[Valveman]

You say you no longer use a pressure tank, but is the pressure switch still wired in? Without a pressure tank you need to be running the pump from the pump start relay in the sprinkler timer. Using the pressure switch without a tank, or even with a tank and not have the zones matched to the pump, it will act like that.

 

[brb649]

Try changing the circuit breaker. Is it 240v or 120v? Is the pump inside or out near the lake with a long electrical run? Is it in conduit or buried UF cable? If it is buried with cable could have been hit or a something chewed it and you have intermittent short.

Thanks, the breaker appears to be ok. I tested it with all the lights on and ran a hair dryer for 9 minutes no problem. Half the lights are down by the lake and on the same cabling as the pump. No brownouts or anything like that.

 

[WorthFlorida]

I have an older 1 HP General Electric water pump that doesn't use a pressure tank and no longer works properly. ......!

What doesn't work properly? The pump or the pressure tank?
As Valveman asked, was there ever a pressure tank? Is this pump used for irrigation or domestic water? If it is a jet pump and pressure switch, it needs a pressure tank.