Using the WDP30 Diaphragm Pump

Using the WDP30 Diaphragm PumpDiaphragm pumps work differently than impeller designs, which means they need to be used differently from more common water and trash pumps. Here’s what you need to know to correctly set up, start and use Honda’s WDP30 Diaphragm Pump.

Before Use

Do a quick check for any signs of leaking oil or gasoline, as well as any other signs of damage. It’s also a good idea to check the tightness of bolts on both the pump and engine.

Inspect the hoses for signs of damage, and make sure the sealing washers and strainer are in good condition.

Check the oil level, fuel level and condition of the air filter. Oil Alert will automatically shut the engine off if the oil level is too low. If the engine stops suddenly, this is the first thing you should check.

Setting Up the Hoses

Instead of spinning an impeller, a diaphragm pump moves a flexible diaphragm up and down, pulling and pushing water. Check valves on the inlet and outlet of this chamber keep this water flowing in one direction. Water is pumped in pulses, and the mechanism reciprocates like a piston in an engine. This shakes the pump and makes the hoses jump around. It’s a good idea to anchor the ends of the hoses and to keep an eye on the pump while it’s running. The pump can start walking if it’s moving fluids with a high solids content.

A strainer must be fitted to the end of the suction hose. The holes may look unusually large if you’re used to other pumps: the pump design lets the WDP30 handle solids up to 2.4 inches in diameter.

Honda rates the WDP30 using both dynamic head, a theoretical maximum pumping height, and static head, the maximum height difference you can have between the inlet and outlet in real-world conditions. Static head is just 25 feet. If the pump is primed, the suction head can be up to 24 feet. Priming time is shorter than other pumps at just 20 seconds with a 20-foot head. If water isn’t exiting the discharge hose after 30 seconds or so, check the placement of the suction hose inlet and the seals around the pump inlet and outlet.

This pump should not be used to move potable water. Using it to pump corrosive liquids including sea water and mine runoff will damage the pump while moving flammable liquids can cause a fire or explosion.


The pump only needs to be primed if the suction head is more than 16 feet. To prime the pump, remove the cap on top of the air cushion chamber, directly above the pump inlet. Pick up the suction hose near the inlet and lift it at least one foot off of the ground. This keeps the priming water from flowing out of the inlet. Pour one gallon of clean water into the chamber. Lower the hose, then screw the cap back onto the chamber.

Starting and Stopping

Controls for the throttle, choke and fuel valve can be found below the air cleaner box, while the ignition switch is located on the starter housing on the opposite side of the engine.

To start the engine, open the fuel valve. If the engine is cold, close the choke. The throttle should be just past the slow position. Turn the ignition switch on, then pull the starter grip. The engine should fire up in one or two pulls. Open the choke as the engine warms up. Once the engine runs smoothly with the choke fully open, the throttle can be set to get the right pumping speed.

The engine can be stopped by turning the ignition off, but it’s easier on the pump if you first close the throttle and let the engine return to idle speed first.

After Use

The pump casing needs to be flushed with water to remove any leftover sediment. Disconnect the suction and discharge hoses, then insert the end of a garden hose into the pump inlet. Turn on the hose. Once the water pouring out of the outlet is clear, remove the hose. Drain any remaining water from the pump housing by lifting the inlet side of the pump or by rolling the right side wheel onto a wood block.

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Storage and Transport Tips for a Honda WDP30 Diaphragm Pump

Honda_WDP30The Honda WDP30 diaphragm pump is designed to move water and debris under the harshest conditions, handling dry conditions, rocks and large solids with ease. Even with a design built for rough punishment, ensuring reliable service means knowing how to properly move and store it when it’s not in use. Continue reading

Honda WDP30 Troubleshooting Guide

Honda_WDP30Honda’s water pumps are among the most durable and reliable pumps on the market, with a number of features that make them both easier to use and easier to maintain. Sometimes, however, even these top-of-the-line water pumps encounter a few operational problems that need to be fixed quickly. Troubleshooting is the best way for pump owners to figure out the exact cause of problems with the pump or its engine, especially during ignition or when beginning the water transfer process. By following a few troubleshooting guidelines at the first sign of a problem, equipment owners can prevent more serious damage and repairs, which might end up being quite costly if they aren’t caught early through one of these diagnostic procedures. Continue reading

How to Service a Honda WDP30 Diaphragm Pump

Honda_WDP30Whether it’s routine maintenance or a crucial repair, servicing the WDP30 diaphragm pump is a key part of ownership. Equipment owners should keep in mind that maintenance and repairs require the same strict adherence to safety guidelines as regular operation, however, and should therefore perform this work in an area with excellent ventilation, a lack of bystanders, and a flat, level surface that will make it easy to handle key parts and pieces of the pump as needed. With those considerations in mind, here’s what operators should know when pursuing water pump service. Continue reading

Honda WDP30 Diaphragm Pump Operation Guide

Honda WH15X Pre-Operation Safety: A Crucial Part of the Process

With any power equipment tool, safety should be a top concern prior to starting the engine and putting it into use. Before getting started with the Honda WDP30 diaphragm pump, make sure to read through the instruction manual and review the basic controls, features, and operational considerations that guide its use. In addition to reading through the instruction manual, check the pump for basic maintenance issues or damage that might have been sustained since it was last used. This includes checking fuel and oil levels, engine condition, hose condition, and the general condition of the pump’s exterior.

An Overview of Diaphragm Pump Operation

Operating a Honda diaphragm pump is actually pretty simple. Operating procedures can generally be broken down into preparation of the pump, priming the pump system, and then learning how to turn the engine on or off as needed. A brief overview of these topics can be found below.

Preparation of the Diaphragm Pump

The key to effectively using the diaphragm pump is to make sure that both of its hoses are functioning properly. If they aren’t, the pump will have a hard time with fluid intake, processing, or discharge, and this could cause maintenance issues in short order.

1. Suction Hose

Make sure that the suction hose being used is either the same size as, or slightly larger than, the suction hose opening on the WDP30 diaphragm pump. A hose that is too small will not be able to connect properly, and this could lead to leaks or other issues during operation. With the proper hose attached, ensure that the pump sits as close as possible to the pumping liquid and that the hose is free of sharp corners and kinks.

2. Discharge Hose

First and foremost, never use a discharge hose that is smaller in diameter than the actual pump output. Keep in mind that a suction hose with a diameter larger than the output will allow for faster discharge with less friction. A smaller hose will experience greater friction and will also reduce the overall amount of discharge. Choose the hose that provides the desired result within WDP30 pump specifications.

Priming the Pump

Priming the pump is an absolutely essential part of operation if the vertical distance from the water to the pump itself measures more than 16 feet. Without priming, the pump may very well sit idle even after the engine has been turned on. To prime the WDP30’s pump, remove the air cushion chamber cap and grasp the suction hose near the hose fitting. Lift the hose about one foot off the ground and then a gallon of water into the pump case via the air cushion chamber. Return the hose to the ground and reinstall the air cushion chamber cap. The fully primed pump will now function properly.

Starting and Stopping the Engine

Proper ignition is a key part of pump ownership, while safely turning the engine off is key to pump storage and long-term durability. To get the engine going, turn the fuel valve on and move the choke lever to its “closed” position. If the engine is still warm from previous use of the pump, operators can skip using the choke and move on to the next stage of engine ignition. Next, turn the ignition switch to the “on” position and move the throttle lever slightly toward the left.

With the throttle lever in place, give the starter grip a firm pull and repeat this process as needed until the engine turns on and stays on. With the engine operating, gradually move the choke lever into the “open” position. Finally, adjust the throttle lever to the appropriate engine speed so that liquid is processed at the appropriate pace. If necessary, throttle adjustments can be made throughout pumping so that the desired speed of discharge is achieved.

To turn the engine off in an emergency, quickly turn the ignition switch to the “off” position. Otherwise, there is a somewhat longer procedure to follow when stopping the engine and preparing the pump for storage. Begin by moving the throttle lever into the “idle” position and turning the ignition switch to the “off” position. Next, turn the fuel valve into its “off” position as well. Before storing the pump, drain the pump chamber and flush it with clean, clear water to remove any residual dirt and debris from the equipment.

Visit for OEM Diaphragm Pump Parts is a great place to find a wide assortment of Honda WDP30 diaphragm pump parts. An online search tool allows operators to find parts according to their pump’s model number, the pump’s engine manufacturer, or the specific part number of the part that they require. This makes it easy to find a part that is perfectly compatible with the WDP30, making even a last-minute, emergency repair easier to perform.