General Pump EZ4040G Plunger Pump | 4.0 GPM @ 4000 PSI | 1" Hollow Shaft

The General Pump EZ4040G is one of the most popular direct-drive triplex plunger pumps on the market for commercial pressure washing skids and premium mobile detailing rigs. Engineered to bolt directly onto a gas engine with a 1-inch horizontal shaft (such as the Honda GX390), this pump eliminates the need for expensive external gearboxes or belt drive configurations.

It features a forged brass manifold, solid ceramic plungers, and a die-cast anodized aluminum crankcase that dissipates heat efficiently. The unit comes complete with a built-in unloader valve and a downstream chemical injector — a compact, plug-and-play choice for fast field replacement.

Specifications

• Flow Rate: 4.0 GPM
• Max Pressure: 4,000 PSI
• Shaft: 1" Hollow Shaft (direct drive)
• Inlet Port: 1/2" FPT
• Outlet Port: 3/8" FPT
• Crankcase Oil Capacity: 14.0 oz (GP Series 100 non-detergent 30W)
• Dry Weight: 14.7 lbs
• Dimensions: 7.9" x 7.3" x 5.6"
• SKU: EZ4040G

Best Use Case

Direct-drive setups running 11–15 HP gas engines. Ideal for roof washing, surface cleaning, and commercial property maintenance.

Pro Maintenance Tip

Direct-drive pumps run at engine speed (3,400 RPM), creating more heat and wear than belt-drive systems. Change pump oil after the first 50 hours of break-in, then every 100 hours thereafter to maximize packing life.