Jet Pump Problems and Repair

How a jet pump works

A jet pump sits above ground, usually beside the pressure tank, and uses its motor and a suction pipe to pull water up from the well. An impeller spins water through a small nozzle and venturi, the "jet," which creates the suction that lifts more water up the pipe.

• Shallow well jet pumps have the jet built into the pump body and work in wells 25 feet deep or less. Goulds gives the practical suction lift at sea level as 25 feet.
• Deep well jet pumps, often convertible models, put the jet assembly down in the well on two pipes. Forbes says they can work in wells as deep as about 100 feet. Goulds says the jet should sit at least 5 feet below the static water level and the system needs a pressure control valve on the discharge.

Everything depends on the pump staying full of water. Suction can't pull air, so any air leak stops it cold.

Likely causes

Goulds' troubleshooting chart lists these causes for the common complaints:

1. 1

   Cause 1: Lost prime from an air leak

   The pump hums, the gauge sits low, and little or no water comes out. Prime it, then find out why it lost prime, or you'll be doing it again next week. Check every threaded joint on the suction side for a hiss or a drip while the pump runs, and look for a sagging or cracked suction line. Full steps are on how to prime a well pump.

2. 2

   Cause 2: Leaking foot valve or check valve

   If the pump has to be reprimed after sitting overnight, or the pressure drops with no taps open, water is draining back down the well. That points to the foot valve at the bottom of the suction pipe or a check valve near the pump. Goulds says a well 2 inches or larger should have a foot valve on the drop pipe, set at least 5 feet off the bottom. See foot valve replacement.

3. 3

   Cause 3: Pressure switch or tank

   A switch with burnt contacts or a clogged pressure tube won't turn the pump on or off on time. A waterlogged tank makes the pump cycle every time a tap opens. Goulds ships its jet pumps at a 30/50 psi switch setting and says the tank pre-charge should be 2 psi below cut-in. Check the tank before you blame the pump; waterlogged pressure tank shows how.

4. 4

   Cause 4: Clogged jet or impeller

   Sand, iron or scale can plug the small jet nozzle or the impeller, which Goulds lists as a cause of weak flow. The pump runs and builds some pressure, but not enough. Cleaning the jet means opening the pump body or pulling the deep well jet, which is fine for a handy owner on a shallow pump and a pro job on a deep one.

5. 5

   Cause 5: Thermal overload tripping

   If the motor stops on its own and restarts after cooling, the thermal protector is tripping. Low voltage, a binding impeller, or a pump running without water all overheat the motor. Find the reason before resetting it again.

6. 6

   Cause 6: Leaking shaft seal

   Water dripping from between the motor and pump body is the shaft seal. It doesn't fix itself, and water running down the shaft into the motor bearings will finish off the motor. A seal kit is cheap; the job is taking the pump body apart without cracking it.

What you can check safely

1. With the power on, read the pressure gauge and listen. Running with low pressure suggests prime or suction trouble; not running at all suggests power, switch or motor.
2. With the power off, check the breaker and look inside the pressure switch for pitted contacts.
3. Check the tank's air charge with the tank drained.
4. Look for wet spots under suction fittings and the shaft seal.
5. Prime the pump once. If it holds pressure and stays primed overnight, you found it.

The pressure switch on many jet pumps sits on a short tube that clogs with sediment. If the switch acts strangely, pull it and clear the tube before replacing anything.

What jet pump repair costs

HomeAdvisor puts typical well pump labor around $50 an hour, plus a $100 to $150 house call fee. If the pump is old and the repair bill climbs, compare it to replacement: HomeGuide puts an installed shallow well jet pump at $400 to $1,000, and a deep well jet at $500 to $1,400.

When to call a pro

Call a well contractor when the pump won't hold prime after you've sealed the obvious leaks, when the deep well jet or foot valve has to come up, or when the motor trips its overload repeatedly. Also call if you're thinking of switching from a deep well jet to a submersible. HomeGuide notes that submersibles often outlast jet pumps, and a contractor can tell you whether your well suits one.