Troubleshooting for diaphragm pumps used in Mytee equipment. Includes troubleshooting chart to diagnose location of a blockage. 

ProblemPossible CauseSolution
Pump doesn’t turn on

Bad switch at control panel

Unbolt the switch plate. We recommend taking a picture of the layout of the wires or tagging the wires for future reference. Switch the wires from the pump switch with the wires from either the vacuum or heater switch. Turn on the vacuum

or heater switch (whichever one you

exchanged wires with). If the pump turns on, the pump switch has failed and needs to be replaced 

(Part # E515)

Loose or disconnected wire

Disconnect the power cord from the

electrical outlet. Open up the machine and look for any loose or disconnected wires. Re-attach or replace wires.

Pump runs but there is no spray

Blockage or kink somewhere in the


See chart below to diagnose the location of the blockage.

Air is in the pump
Prime the pump

Remove QD off the machine and solution hose. Make sure that the three-prong clip on the inside of the threaded end is evenly aligned below the thread of the QD

Pump runs but there is no spray

(units equipped with internal

heaters only)

On a unit equipped with a heater,

the check valve between the pump

and heater may hang up, causing the

flow of water to be impeded or stop


Remove the check valve temporarily and check to see if the pump will flow water out of the pump outlet hose when the pump is turned on for a brief instant in order to verify cause. The remedy is to install a new check valve. Observe the proper orientation (flow direction) of the check valve



Pump runs for a second then shuts


QD is pressure locked

Relieve pressure from behind the QD by pressing in the button inside the QD

Check valve is clogged

Remove check valve and see if the ball inside the valve is moving freely. If not apply a couple drops of lubricant

Solution lines and/or jets are clogged

Check and clean the jets and the solution line

The jet nozzle could be too large

Replace the jet with one that has a smaller opening

Pump doesn’t stop running

Leak somewhere in the line

Disconnect your tool's solution hose from the machine. If this causes the pump to stop running, then the problem is outside the machine, either in the solution hose or tool. If it continues running on, open the machine and check for leaks. If there are no leaks, run Mytee’s System Maintainer™ through the machine to clear blockages

Cracks or vacuum leaks on inlet side

of pump

Make sure hoses are secured tightly. If

the inlet side of the pump is cracked or damaged, replace the pump.

Click here for important information

regarding the use of brass fittings on the plastic pump head

Seals have been degraded by


Replace pump 

Debris blocking inlet filter or pump


Clean filter and/or pump head

Pump trips circuit breaker when

turned on

Short in power switch

Test by swapping vacuum and pump

switch. If problem resolves, but vacuum begins tripping breaker, replace switch

(Part # E515)

Short in electrical harness

Risk of electric shock. Do this at your own risk.

Remove pump from circuit by attaching power leads together. If breaker still pops when switch is toggled, then there is a short to the ground in the circuit. Replace

wires as needed.

Short in pump motor

If switch and harness check is OK, the

short may be in the pump motor. Replace pump

Troubleshooting Chart

If there is no spray coming from your pump, consult this troubleshooting chart to find a solution.