The P90GH features a Keene P90 pump mounted to a Honda GX50 engine. The Keene centrifugal pump has been an industry standard for decades. The P90 is a non-self-priming centrifugal water pump designed to be both light in weight while also highly efficient at pumping large volumes of water at high pressure. Self priming pumps are inefficient because the self-priming mechanism actually impedes the flow of the water. A centrifugal pump benefits from its simpler design making them desired for high volume/high pressure applications like fire-fighting and powering suction dredges. The P90 pump is capable of up to 100 gallons per minute and has a maximum head lift of 161 feet. The pump has a 1.5″ clamp on style hose intake and a 1.25″ threaded pump output. The pump also features a capped 5/8″ male garden hose outlet, which can be used with optional crevice flushing kits or a garden hose for rinsing out buckets or sluice boxes.

Keene P90 Pump Breakdown Diagram

Before starting the engine, a centrifugal pump must be fully primed. This means the pump must be full of water and all air removed. All Keene jetting pumps have a mechanical water pump seal. Without the presence of water in the pump, friction could cause a seal to overheat and require replacement. Priming the pump on smaller models like the P90 is accomplished by thrusting a foot valve on the end of the pump intake hose back and forth under the surface of the water in a reciprocating motion. This will pump water into the foot valve assembly and into the pump. A pump is fully primed when water is observed flowing out of the discharge end of the pump. It may sometimes become necessary to hold the discharge hose above the level of the pump to complete the priming operation. Caution must be exercised to prevent sand from entering the foot valve or intake portion of the pump for excessive periods of time. The aluminum impeller is quite tough and can handle a lot of abuse, but excess amounts of sand will result in premature wear and could damage the water pump seal or pump impeller. It is recommended that the intake portion of the foot valve be placed in a rocky sand free environment underwater, or in a small bucket or pan if the bottom is nothing but sand. It is imperative that the intake is submerged enough to never suck any air as any amount of air can break the prime, causing the pump to run dry and burning up the pump seal in just a few minutes. It is a good idea for remote jobs to always have a spare pump seal on hand. With care it will never be needed but is cheap insurance against costly down time.