Web Exclusive: Keep It Pumping
by Dale Gabrielse
May 9, 2008
This how-to guide to preventative maintenance will help you avoid pump downtime.
You’re pumping away on your jobsite, things are flowing along just fine—and then it happens. Well, nothing happens, actually. That’s the problem. Something clogged or broke--and the only thing pumping now is that vein in your forehead.
While it’s often the most neglected part of the owner’s manual, preventative maintenance checks and services can thwart major problems down the pipeline. Following the basic steps described in this article can help keep a pump flowing so your jobs run smoothly.
The Daily Pump Inspection
Start each day with an inspection to ensure the pump is ready to run. One of the most important daily checks is checking the quality and level of engine oil. An insufficient amount of oil can cause serious problems and ultimately decrease the life of an engine. If the oil level is below what is recommended by the manufacturer, oil should be added until the specified level is reached.
Check the gasoline level, making sure there is enough for the upcoming usage. Examine the engine parts, and look underneath for evidence of oil or fuel leaks. If a fluid is dripping, inspect the area for parts that may need to be tightened or replaced. Continue to check the rest of the machine for broken bolts, nuts or other loose parts.
Checking the condition of the air filter is another important daily maintenance practice that can prevent significant damage. A clogged, wet, dirty or damaged air filter can lead to a loss in power and shorten the life of an engine by allowing dirt or water into sensitive areas.
Inspect the condition of the hoses regularly. If they are worn, frayed or have any holes, the air gaps will likely cause the pump to lose suction. Patch any holes and seal leaking joints. A severely worn hose should be replaced.
The most important thing to remember for daily maintenance is priming the pump before starting. Running a pump dry will damage the seals, which can start a domino effect of problems. When it comes to self-priming pumps, remember: Just add water. The term “self-priming” may be considered a misnomer--the operator must still add water to the pump each time it is used. The pump will then take over, build pressure within the volute and begin discharging.
One more thing to check before starting a pump is the area where it will be placed. Gasoline engines and mufflers are prone to spark, which can ignite grass or weeds in the area if a spark arrestor is not used. Ensure the pump is on level ground. If it is set on a slope, the fluids will not be evenly distributed, which will affect oil lubrication and fuel levels.
Semimonthly Inspections
Once the pump has been readied, get right to work. Remember that other maintenance checks and services will still need to be done--just on a less frequent basis. Generally, quality pump engines can be expected to last upward of 2,500 hours of operation. Following recommended maintenance schedules can increase that length of time.
A few things need to be checked a couple of times a month, other things even less frequently. Clean the air filter semimonthly by pulling out the paper filter and tapping it against a hard surface to remove excess dirt. When cleaning the filter, never use an air compressor because it can tear holes in the paper.
Check the spark plugs semimonthly by looking for dirt, damage or excessive carbon build-up. Dirty spark plugs can cause a decrease in power and poor starting performance. Spark plugs coated with a considerable amount of dirt or carbon build-up should be cleaned with a wire brush or spark plug cleaner. If the build-up seems excessive it may be a sign of weak spark voltage, an incorrect carburetor adjustment, a lack of air cleaner maintenance or an incorrect fuel-air mixture. Check the electrode gap on the spark plugs to ensure it still meets the manufacturer’s specifications, and adjust as needed. If any spark plug has cracked porcelain, replace immediately.
Monthly Inspections
It is important to clean and inspect the fuel strainer and fuel filter every month. Contaminated fuel that is not removed can lead to trouble with engine starts. Replacing the fuel line and carburetor is expensive, so it is essential to prevent unnecessary damage caused by contaminated fuel.
On an annual basis, inspect the pump for dirty, broken or misaligned parts. Such parts can cause problems with the engine or pump components. Inspecting the entire machine gives the most comprehensive view of what needs to be cleaned and repaired.
Dusty conditions typically shorten the length of time between regular services since extreme dust can clog filter elements or contaminate fuel and oil. Adjust regular maintenance schedules as needed to account for less-than-optimal conditions.
Troubleshooting Pump Problems
Preventative maintenance won’t stop every problem that might occur with pump operation. Knowing what to look for and addressing it quickly will keep the problem from becoming a more expensive, time-intensive repair.
If a pump simply won’t run, the culprit is likely the impeller or engine. If the impeller is sticking, disassemble, clean and reinstall it. Several different things could be causing the engine to not start. Check to see if the spark plug is fouled, if it’s dirty, clean it with a wire brush or replace it. If it’s clean, connect it to the plug cap and ground the plug against the engine body. Pull the starter to see if the spark is weak or nonexistent. If a new plug doesn’t spark, the ignition system is faulty and will need repairs.
The engine also might not start if the spark plug is loose--causing little resistance through the starter handle and a lack of compression--or if the plug is wet with fuel. If the spark plug is wet, check to see that the fuel cock is closed. Then close the choke lever and pull the starter handle a half-dozen times to see if the electrode becomes wet. If it does become wet, the problem may be that the fuel is stale, in which case it should be drained and refilled with fresh fuel. If the electrode is dry, the problem may be with the fuel intake of the carburetor. Try to see where the fuel stops in the engine. Take the pump to a dealer for repairs if these checks do not help in getting the engine to start again.
Pumping Volume
A number of other things could cause a pump to not self-prime. Start by checking the air on the suction side of the pump; tighten the suction hose or pipe, if needed. Check the drain plug to ensure that it has been tightened completely. Insufficient water inside the pump casing will also prevent the pump from priming. If the engine speed is too low or there is air sucking around a mechanical seal, consult a dealer for assistance.
Engine speed also can affect pumping volume. If the pumping volume has dropped, check the wear on the impeller, see if the suction hose may be too thin or too long, or retighten any loose parts on the suction chamber. Dropped pumping volume might also be caused by a high suction lift that needs to be lowered, water leaking from the water passage, a broken mechanical seal, or a drop in engine output or speed.
Clogs also affect pumping volume. Adding a strainer will help prevent clogs and prolong the pump’s life. Strainers’ hole sizes vary with the type of pump being used. The purpose is to prevent debris larger than what the pump can handle from entering the intake hose and damaging the pump. Plastic strainers can break over time and clog the pump; buying a pump with a metal strainer may increase service life.
The Hose Size
The hose size--which should never be smaller than the suction port--can also affect the life of a pump. Hoses that are too narrow or too long may cause cavitation or water hammer.
With cavitation, low-pressure vapor bubbles quickly form and collapse along the impeller’s vanes. The liquid will actually look like it’s boiling--even if it’s not hot--when the surface pressure drops far enough. Cavitation occurs in centrifugal pumps when the suction vacuum increases to a point that water vapor bubbles can no longer be formed along the impeller. The bubbles instead jet across the impeller with the sudden pressure increase, which may damage the impeller.
Water hammer occurs when the liquid flowing through the pump suddenly stops. The quick shut- off will knock the fluid in reverse with a bang, transmitting energy back to the pump. This energy transfer causes the pressure to elevate quickly, which might damage the pump’s casing.
If a pump’s performance seems to be declining after several years of use, replacing the shims should address the problem by lessening the tolerance between the impeller and the volute.
Playing it Safe with Pump Maintenance
Operators should use extreme caution when performing any type of pump maintenance. Some safety measures are generally common sense. Any type of flame should be avoided while cleaning the fuel cup, replacing a fuel hose or draining gasoline from the engine before storing the pump. Flames should also be avoided when cleaning the air cleaner since the foam filter may be saturated with kerosene or fuel.
Most people know that engines produce carbon monoxide, which is a lethal gas. Engines should only be operated in a well-ventilated area, which does not mean in a shop with a window or two open. The more open the area, the better--especially when it comes to safe engine operation.
Use caution when working with spark plugs. When testing for a fouled spark plug, begin by moving the plug away from the spark plug hole and wiping out any spilled fuel. Whenever the starting handle is pulled during a spark plug test, ground the plug against the engine’s body. Never hold a spark plug by hand while pulling the recoil starter.
Engine temperatures can be harmful. When changing an engine’s oil, for example, the engine should be warm. A very warm or hot engine will hold hot oil, which can cause serious burns if it contacts skin. Avoid contact with the muffler on a hot engine; it can reach temperatures up to 1,200 degrees Fahrenheit.
The heat of an engine can ignite combustible materials in the area, such as dried leaves and brush. Adding a spark arrester will reduce this risk if the pump needs to be operated in a dry or wooded area. Some local laws may require the use of a spark arrester, so it’s worth checking regulations. Keeping the spark arrester clean will ensure it continues to operate as intended. Wait until the engine has cooled to clean a clogged spark arrester. Use a brush--an old but clean toothbrush should work fine--to carefully clean the screen. Before reinstalling it, check for any breaks or holes in the screen, which indicate that it needs to be replaced.
Also, exercise care with the flywheel and recoil cord. Never strike a flywheel with a tool, it could later shatter during operation. Use caution when pulling the starter cord, which could pull back more forcefully than expected, jerking the operator’s arm forward and resulting in bruises, sprains or fractures.
Keep Pumps Flowing
Following specific timelines laid out in the owner’s manual will ensure that maintenance services won’t be neglected, which can start a domino effect of trouble as the pump breaks, time is lost and repair costs add up. Safely troubleshooting and repairing small problems will prevent injuries or additional repair work.
In the end, all of these steps together should keep a pump flowing and the operator safe. If all else fails, there’s always the owner’s manual, too. It’s practically as good as aspirin when it comes to easing any headaches brought on by a missed maintenance step.
To read more about how to select the right pump for the job, click to “Don’t Just Go With the Flow.” www.siteprepmag.com/CDA/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000329888
Dale Gabrielse
Dale Gabrielse is the training manager for Subaru Robin in Wood Dale, Illinois.
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