Termite Injection Pump Maintenance: The Essential Safe Guide
By Pest Tech TeamPublished 6 min readEquipment
Drill-fill-seal termite treatment depends on one machine more than any other: the pump that injects termiticide into the soil under the floor. If pressure drops or surges, holes are under-dosed, the barrier has gaps, and the treatment may fail months later. Good termite injection pump maintenance is therefore part of treatment quality, not just equipment care. This guide covers HTP and triplex plunger pumps — the most common types used by termite teams in Pakistan.
How HTP and triplex pumps work
HTP (high-pressure) power sprayers use a piston or plunger pump driven by a small petrol engine or electric motor. Triplex pumps have three plungers working in turn, which gives smoother flow and steady pressure. The basic parts are:
- Crankcase with oil, driving the plungers.
- Plungers and seals (packings) that push the liquid.
- Inlet and outlet valves for each cylinder.
- Suction hose and strainer drawing liquid from the tank.
- Unloader / pressure regulator that controls working pressure and bypasses excess flow back to the tank.
- Pressure gauge, delivery hose and injection lance or rod.
Termite injection pump maintenance: daily routine
- Check the crankcase oil level through the sight glass or dipstick before starting.
- Check the suction strainer — clean it if there is any debris.
- Prime the pump (see below) and check pressure builds smoothly.
- Watch the gauge while working. A needle that swings widely or drops suggests air in the suction or worn valves.
- Flush after every job — run clean water through the pump, hoses and lance for a few minutes to remove termiticide.
- Release pressure and set the unloader back to low before storing.
- Wipe down and check for oil or liquid leaks.
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Oil changes
The crankcase oil protects the bearings and connecting rods. Change it:
- After the first running-in period on a new pump, as the manual specifies.
- Then at the interval in the manual, or sooner in heavy use.
- Immediately if the oil looks milky — that means water or chemical has entered through worn plunger seals, which must also be replaced.
Use the grade of oil the manufacturer recommends.
Seals and valves
Plunger seals and valves are wear parts. Signs they need attention:
| Sign | Likely cause |
|---|---|
| Liquid dripping from under the pump head | Worn plunger seals |
| Milky crankcase oil | Seals leaking into the crankcase |
| Pressure fluctuates or pulses | Worn or dirty valve, or air in suction |
| Pressure will not reach normal level | Worn seals, valves or unloader problem |
| Knocking noise | Air in suction, stuck valve or worn bearing |
Keep a seal and valve kit for your pump model. Replacing seals before the busy season is far cheaper than a pump failure halfway through a job.
Priming: when the pump loses prime
A pump that "loses prime" draws air instead of liquid. Pressure drops or disappears, and the pump may rattle. Causes and fixes:
- Air leak in the suction hose or fittings — tighten clamps, replace cracked hoses and worn washers.
- Blocked suction strainer — clean it.
- Tank running low — keep the suction end well below the liquid surface.
- Suction hose kinked or collapsed — replace with a reinforced hose.
- Stuck inlet valve — clean or replace.
To prime, open the unloader to low pressure, run the pump with the delivery open until a steady flow without bubbles appears, then close the delivery and raise pressure gradually. Our troubleshooting entry for a termite or HTP pump losing pressure lists the checks in order.
Setting the unloader
The unloader sets the working pressure. For termite injection, you need enough pressure to deliver the dose into the soil through the injection rod — not the maximum the pump can produce. Too much pressure wears seals faster, stresses hoses and can blow soil back out of the hole. Set pressure according to the equipment manual and your treatment method, and check the gauge regularly.
Pressure gauge
A faulty gauge gives false confidence. If the needle sticks, does not return to zero, or reads differently from a known good gauge, replace it. Glycerine-filled gauges resist vibration better on engine-driven pumps.
Why steady pressure matters for treatment
In drill-fill-seal work, each hole should receive the volume of diluted termiticide set by the label for the depth and spacing. Unsteady pressure means inconsistent volumes — some holes under-dosed, leaving gaps in the soil barrier. Our pre construction termite treatment guide explains label doses and why a continuous barrier is essential.
A simple daily calibration check
At the start of each job, set your working pressure, then inject into a measuring bucket for a timed period through the same rod and tip you will use on site. Compare the volume with what each hole should receive. If the flow is far off, adjust pressure or timing before you start drilling — not halfway through the house. Record the result in your job sheet; it is useful evidence if a treatment is ever questioned.
Storage and the off-season
Karachi does not freeze, but long storage in heat still damages pumps:
- Flush with clean water, then run briefly with the delivery open to empty the pump.
- Store the pump in shade, away from direct sun.
- Change the oil before long storage if it is due.
- Disconnect hoses and store them coiled without kinks.
- Turn the engine or motor over by hand every few weeks to keep seals from sticking.
- For engine-driven pumps, drain the carburettor or use fresh fuel when restarting.
Hoses and lances
- Inspect high-pressure hoses for bulges, cracks and worn outer covers.
- Replace hoses with damaged fittings — never repair high-pressure hoses with tape.
- Clean injection rod tips and check for blockages.
When to bring it in
Bring the pump to our workshop if it has knocking from the crankcase, persistent milky oil, cracked manifolds, worn plungers, or will not hold pressure after new seals and valves. Our spray machine and fogger repair service repairs termite injection and HTP pumps and quotes before starting work. Termite teams working on large sites — including new construction in areas such as Bahria Town — often book a pump service before the pre-construction season. For the general care of smaller sprayers used on the same jobs, see knapsack sprayer maintenance.
Solo's sprayer repair support page is a useful general reference alongside your pump manual.
Talk to Pest Tech
Send a photo of your pump's model plate and a short video of the gauge and pump running on WhatsApp. The first diagnosis is free. Pest Tech has used termite injection pumps on its own jobs in Karachi since 2005.
Frequently asked questions
How often should I change the oil in a triplex pump?
After the running-in period, then at the interval in your pump’s manual, or sooner in heavy use. Change it immediately if the oil looks milky.
Why does my termite pump keep losing prime?
Usually an air leak in the suction hose or fittings, a blocked strainer, a low tank level, a collapsed suction hose or a stuck inlet valve.
My pressure gauge needle swings. Is the gauge faulty?
Not always — it often means air in the suction or worn valves. If the needle sticks or does not return to zero, replace the gauge.
What pressure should I use for termite injection?
Enough to deliver the label dose into the soil, as set out in your equipment manual and treatment method — not the pump’s maximum.