Pressure Washer Pumps

The pump is the heart of your machine, and buying the wrong one costs you twice. Sun Brite Supply stocks over 350 pumps from General Pump, CAT, AR, Comet, Udor, and Giant at our Gaithersburg, MD counter, with same-day pickup and honest sizing help. Not sure which pump fits your engine? Call 301-519-9274 with your engine model and GPM target and we will spec it in five minutes.

How to Choose a Pressure Washer Pump

Match four things and you cannot go wrong: flow (GPM), pressure (PSI), shaft, and drive type. Flow determines how fast you rinse, and for contractors flow is money. Pressure matters less than most people think once you are above 3,000 PSI. The shaft must match your engine: 3/4" or 1" horizontal gas flange for most gas engines, 7/8" vertical for vertical-shaft machines, 24mm solid shaft for belt drive setups. Get the shaft wrong and the pump goes back in the box.

Belt Drive vs Direct Drive

Direct drive bolts the pump straight to the engine shaft, so the pump spins at engine speed, around 3,400 RPM. It costs less and fits tighter spaces, but heat and RPM wear the packings faster. Belt drive uses pulleys to cut pump speed to about 1,450 RPM. The pump runs cooler, vibrates less, and routinely lasts 3 to 5 times longer. If you wash for a living, belt drive pays for itself. If you wash on weekends, direct drive is the smart buy.

In-Stock Pump Comparison

Prices and stock change. Every pump above was on our shelf when this page was updated, and we can check stock in one call.

From the Field

What 30 years behind this counter has taught us about pumps: the number one killer is not hours, it is oil. Change pump oil every 50 hours or monthly and most triplex pumps outlast the machine around them. The number two killer is running the pump dry or letting it bypass too long. If your unloader keeps the pump in bypass for more than a minute or two, the water in the head gets hot enough to cook the packings. And when a pump starts pulsing or losing pressure, do not buy a new pump yet. Nine times out of ten it needs a $30 to $130 repair kit, not a $900 replacement. Bring it in and we will tell you which one you actually need.

Shop by Brand and Type

• General Pumps and General Pump parts
• CAT Pumps and CAT pump parts
• AR Pumps and AR pump parts
• Comet Pumps and Comet pump parts
• Udor Pumps and Giant Pumps
• Pumps Made Ready (assembled with unloader and fittings, tested, ready to bolt on)
• 120V electric pumps and 12V soft wash pumps
• Unloader valves and pump oil

Frequently Asked Questions

How do I know what GPM and PSI pump I need?

Start with your engine horsepower. A rough rule: HP = (GPM x PSI) / 1100. A 13 HP engine handles a 4 GPM at 4,000 PSI pump. More GPM means faster rinsing, which matters more than extra PSI for most cleaning work.

What is the difference between belt drive and direct drive pumps?

Direct drive pumps bolt to the engine and spin at about 3,400 RPM. Belt drive pumps run near 1,450 RPM, so they run cooler and last 3 to 5 times longer. Belt drive costs more up front and pays off with daily use.

How do I match a pump to my engine shaft?

Measure the shaft: 3/4" and 1" horizontal shafts take gas flange pumps, 7/8" vertical shafts take vertical pumps, and belt setups use 24mm solid shaft pumps with pulleys. Call us with your engine model and we will confirm the fit.

Why is my pump losing pressure or pulsing?

Usually worn packings or a fouled valve, not a dead pump. A repair kit fixes it for a fraction of replacement cost. Pulsing can also come from a clogged inlet filter or a sucked-flat supply line, so check those first.

How often should I change pump oil?

Every 50 hours of use or monthly, whichever comes first, with pump-specific oil, never motor oil. Milky oil means water intrusion and the seals need attention soon.

Can I upgrade my direct drive machine to belt drive?

Yes. You need a solid-shaft pump, pulleys, a belt, and mounting rails. Our Pumps Made Ready assemblies make the swap simpler, and we can walk you through the parts list.

Do you help with pump sizing over the phone?

Every day. Call 301-519-9274 with your engine model and what you clean, and we will spec the right pump before you spend a dollar. Local? Visit our Gaithersburg store for same-day pickup.