FREQUENTLY ASKED QUESTIONS

Mobile Lawnmower, Small Engine and Generator Repair Service

1. Who is My Mobile Mechanic, LLC?

My Mobile Mechanic, LLC is a group of locally owned and operated mobile mechanic service. We are based in Harford County, Md, and we service equipment at your home or place of business. This business was started by John Helmer who saw the need to create a small engine repair service that took the hassle out of dealing with conventional shops. Our primary goal is to make it both easy and cost-effective for you to get your power equipment serviced.

2. What is included in your advertised tune-up price?

Everything for the tune-up is included in our low advertised price. My Mobile Mechanic, LLC never charge for unlisted extras. We bring everything we need for the job in our fully-stocked vans. In the case that your unit needs a part we don’t have, we’ll get it to you in a matter of days and finish the job at no extra charge.

3. Do I have to pay an extra pick-up or delivery charge?

No! This is the entire premise of our philosophy. We come to you and do the work at your site so there is no pick up or delivery charge. If your equipment requires parts that have to be ordered, or we need to take the unit with us, there is a one time service call charge of $99 even if we have to make multiple trips. You just pay for parts and labor. All services on our booking page already include the service call fee in the price of the service.

4. What type of oil should I use in my small engine?

Not all motor oils are the same. To put it simply, in warmer climates, most engines need thicker oil. In colder climates, most engines need thinner oil. Oil is measured by its thickness or viscosity (how fast if flows). For example, 40-weight oil is thicker than 30-weight oil. The “W” in 10W40 stands for winter, which means that in winter, this particular oil behaves like 40-weight. Using the wrong oil can cause problems with starting and poor gas consumption.

5. How often should my lawn mower, tractor or snow blower be serviced?

Most manufacturers recommend servicing your equipment at least once a year. All small engines use petroleum-based products. As the additives in the petroleum break down and the oil and gas is left to settle over long periods of time, it can cause sludge and a gummy residue. This residue can cause engines to “hunt and surge” or, worse, break down. Also, the sludge can block key lubricating points resulting in rapid and excessive wear. Eventually, the engine could become completely ruined.

6. How often should I sharpen my mowing blades?

Sharpening cycles depend on the conditions encountered by the mower. In sandy or very dry conditions, the blades may need sharpening every two to three hours. At a minimum, the blades should be checked and sharpened, if necessary, before each day of operation. Tip: Keep an extra set of sharp blades handy to replace those that become dull or damaged during daily operation.

7. What type of oil should I use in the hydraulic system?

Any high-quality 15W40, 15W50 fully synthetic motor oil can be used.

8. How often should I check and service the hydraulic system?

Hydraulic oil should be checked daily. Make sure the top of the tank is clean before removing the fill cap. Oil level should be one inch below the top of the tank. The hydraulic oil and filter should be changed every 500 hours, or once before the mowing season. Instructions for the oil and filter change can be found in the operator’s manual.

9. How can I correct poor discharge or uneven cut?

Poor discharge is a factor of blade tip and ground travel speed. Always mow with the engine operating at full speed. Regulate operation control with ground speed. At high ground speeds, the blades cannot cut the grass efficiently. When grass is high, slow down your ground speed. Never cut more than 1/3 of the grass height. In high or lush grasses, the mower should be operated at its highest level of cut, and then re-cut at the final desired height. Uneven cut can be due to something as simple as incorrect tire pressure. Check your operator’s manual for correct tire pressure. Poor discharge and uneven cut can also be caused by damaged, unbalanced, or dull blades. Grass build-up under the deck can damage or wear the deck belt. Check the operator’s manual on how to correctly set the cutting height of the deck.

10. Can ethonol fuel ruin my equipment?

YES, Gas is only good for 3-4 months TOPS. Run the gas out of your equipment at the end of the season and use a good quality stabilizer.

11. What happens if I have to cancel my appointment?

Please call us at least 24 hours in advance of our scheduled arrival time so we can reschedule. Any appointments not cancelled previous to that 24-hour window will incur a service call charge.

Ignition Systems

Troubleshooting Ignition Systems in Your Lawn Mower or Small Engine

How Do Ignition Systems Work in Small Engines & Lawn Mowers?

The ignition system is the starting system for your small engine. Whether you start the engine with a pull rope or the turn of a key on an electric start motor, you're relying on the ignition system to produce a spark inside the combustion chamber.

When you start your lawn mower or small engine, you turn the flywheel and its magnets pass the coil (or armature). This creates a spark. The ignition system coordinates the timing so that the spark will ignite the air-fuel mixture in the combustion chamber just as it reaches maximum compression in each engine cycle- thus, maximizing the engine’s power.

Once the engine is running, the flywheel keeps rotating, the magnets keep passing the coil and the spark plug keep firing based on a specific timing.

Types of Ignition Systems

Solid-state systems: the more modern option, these systems use a tiny transistor in the coil or armature to close the electrical circuit that travels through the spark plug lead to the spark plug(s)
Breaker point systems: used on engines made before 1980, these systems use a mechanical switch instead of a transistor to close the electrical circuit used to produce a spark

How To Test the Ignition Coil in Your Small Engine

The coil is probably the easiest thing to check and therefore the first thing to check when embarking upon ignition system troubleshooting.

Testing the Coil or Armature

Clip one end of the spark tester (service part number 19368) to the ignition cable and the other grounded to the cylinder head
Spin the flywheel rapidly (at least 350 RPM) and watch for spark in the tester window

If the spark jumps the tester gap, your ignition coil is working fine. If not, it needs to be replaced.

Engine quits while running? Hook the tester up between the ignition cable and the spark plug and start the engine. When it stops, monitor the window.

Common Mistakes When Testing Coils

Be sure to unhook the coil from the equipment wiring harness as well as the engine's wiring harness and use the spark tester. Make sure the coil grounding lead is not shorting out against a piece of sheet metal
DO NOT attach the tester to the spark plug for this test. The engine may start. Without the grounding lead installed, you won't be able to turn it off

Replacing Ignition Coils or Armatures

An ignition armature must be set at a precise distance from the flywheel. Your engine repair manual will provide the proper gap for your engine. Common armature gap ranges are .006 - .010" and .010 - .014". Armatures are often packaged with a shim to assist in setting the gap.

Unhook the spark plug wire and secure it, removing any batteries, if equipped
Remove the old ignition coil (armature) mounting screws
Disconnect the stop switch wire from the flywheel brake and remove the coil
Attach a replacement coil using mounting screws
Push the coil (armature) away from the flywheel and tighten one screw
Turn the flywheel so the magnets are on the opposite side from the ignition coil (armature)
Place the appropriate shim between the rim of the flywheel and the ignition armature. While holding the shim, turn the flywheel until the magnets are directly adjacent to the armature
Loosen the tight screw so the magnets pull the ignition armature against the flywheel and shim. Then, tighten both mounting screws and rotate the flywheel until the shim slips free
Reconnect the stop switch

Testing & Replacing a Stop Switch

Insert the spark plug lead on one end of a spark tester and attach the tester's alligator clip to ground, such as an engine bolt
Place the equipment stop switch control in the OFF or STOP position. If the engine is not connected to the equipment, ground the stop switch wire to the cylinder
Attempt to start the engine using the rewind cord or key (if equipped)
There should be no spark. If a spark appears, inspect the stop switch for damage
Place the stop switch control in RUN or START position
If the engine is not connected to the equipment, make sure the stop switch wire is not grounded
Attempt to start the engine

A spark should be visible in the tester. If no spark appears, check for broken wires, shorts, grounds or a defective stop switch.

Once you have confirmed that the stop switch is working, reconnect the spark plug lead.

Ignition Module Failure

Because the ignition module is electronic and does not utilize moving components, it is normally one of the most reliable part of the engine. When it does fail, it is usually due to heat caused from improper wiring of the ground wire to battery voltage.

If the engine does not produce spark, other areas of the ignition system should be checked before focusing on the ignition module as source of failure (see above).

If no fault is discovered, the ignition module itself may need to be examined. To best determine the cause of failure, please consult with us.

Common Flywheel Problems

If you are experiencing ignition timing issues, this is most often due to a sheared flywheel key. You can also test the flywheel magnets for any potential issues.

For information regarding this, please visit our Inspecting the Flywheel and Key FAQ.

Common Spark Plug Problems

The required spark plug gap and voltage can vary depending on temperature, altitude and your engine settings
Old, damaged or fouled spark plugs can also require service or replacement

Carburetor Maintenance

How to Clean a Small Engine Carburetor

Follow these steps to check your Carburetor

1. Check the Air Filter

Make sure that the air coming into the carburetor is clean and free of debris by inspecting the air filter. A clogged air filter is a common cause for black smoke emitting from the exhaust.

2. Check the Connections

The connections attached to the carburetors' throttle and choke plates can bind or stick when dirty. Constant vibration and wear can affect the setting of the carburetor's mixture screws.

3. Use carburetor cleaner to remove deposits, clogs & debris

With all of the grass, twigs and other debris that a small engine encounters, it's not surprising that even passages inside the carburetor eventually pay a price. Deposits inside the carburetor can clog fuel and air passages and reduce performance or stop the engine altogether.

Luckily, you can take care of many of these problems quickly and easily; often without even removing the carburetor from the engine. Commercially available carburetor cleaner comes in convenient spray cans for periodic cleaning of both inside and outside the carburetor.

In addition to cleaning the carburetor, many engine performance problems can be linked to maintenance issues such as stale fuel, dirty air filter, fouled spark plug, and deteriorated oil. A great way to help avoid these problems would be to perform an annual tune-up.

4. Contact My Mobile Mechanic

If you continue to encounter problems with your Carburetor, we recommend calling us.