How to read Craftsman serial number?
On a Craftsman gas lawn mower like model CMXGMAM2703840, the serial number format depends on who built the mower and which ID tag you are reading. We use the serial number mainly to identify the production run; for parts ordering, the model number CMXGMAM2703840 is the key identifier.
Where to find the serial number
Most walk-behind mowers place the serial number on a sticker or metal tag in one of these spots:
- On the rear of the deck near the discharge opening
- On top of the deck near the engine mounting area
- On the back panel near the bagger opening (rear discharge models)
- Near the height-adjuster bracket on the deck
If the tag is worn, cleaning the area can make the digits readable.
How to interpret the serial number (what usually works)
Craftsman serial numbers are not universal across all mower builders. Here are the most common patterns we see:
- Date-coded serials: a block of digits that represents month, day, and year
- Plant and run codes: letters or digits that identify the factory and production batch
- Engine serial vs. mower serial: the engine has its own serial number that does not date the mower deck
Quick check table
| What you’re reading | What it tells you | What to use for parts |
|---|---|---|
| Mower model number | Exact product family | Use this first (CMXGMAM2703840) |
| Mower serial number | Production run info | Helpful, but usually not required |
| Engine model/type code | Engine-specific ID | Use for engine-only parts |
Why it matters
Serial numbers can help confirm the correct production version when a model has mid-year changes, but the fastest way to get the right blade, wheel, or bagger part is matching by model and diagram.
If you’re replacing common wear items, start with parts that frequently match this mower’s deck and bagging setup, such as the lawn mower grass bag 664P05321A or the lawn mower blade brake and clutch cable 946-04703A.
Last updated: February 2026
What are the common problems with Craftsman lawn mowers?
Common problems on the Craftsman CMXGMAM2703840 gas lawn mower are no-start or hard-start issues (fuel, spark, air), starts then dies (fuel delivery or carburetion), poor cut quality (blade or blade adapter wear), and safety or control problems (blade brake cable out of adjustment). Many fixes start with basic maintenance parts like the air filter and spark plug.
Most common symptoms and what they usually mean
- Won’t start: stale fuel, fouled spark plug, clogged air filter, or restricted fuel flow
- Starts then dies: partially clogged carburetor, dirty fuel, or a venting issue at the fuel cap
- Runs rough or surges: dirty carburetor jets, air leak, or old fuel
- Poor cut or vibration: bent/dull blade, debris packed under the deck, or a worn blade adapter
- Blade won’t stay engaged: blade brake and clutch cable stretched, misrouted, or binding
- Clumping or poor bagging: wet grass, clogged deck, or bag/deflector issues
Quick checks we recommend (in order)
- Drain old fuel and refill with fresh fuel.
- Inspect and replace the air filter if it is dirty or oil-soaked.
- Inspect and replace the spark plug if it is fouled or the electrode is worn.
- Check the blade area for packed grass and confirm the blade bolt is tight.
- Verify the operator presence control and blade control lever move freely and fully return.
Parts that commonly solve these problems
| Problem you see | Part to inspect first | What it affects |
|---|---|---|
| Hard starting, low power | Lawn & garden equipment engine air filter 951-14628 | Airflow and fuel mixture |
| No spark, misfire | Lawn & garden equipment engine spark plug 951-14437 | Ignition quality |
| Vibration, uneven cut | Mtd lawn mower blade adapter 748-0376E | Blade mounting and alignment |
| Blade won’t engage or stops | Lawn mower blade brake and clutch cable 946-04703A | Blade brake release and engagement |
Why it matters
Most “mower problems” trace back to airflow, fuel quality, or blade condition. Fixing those basics first prevents repeat no-start issues, improves cut quality, and reduces wear on the engine and deck components.
Last updated: February 2026
How to tell if a lawn mower ignition coil is bad?
A bad ignition coil on your Craftsman CMXGMAM2703840 gas lawn mower usually shows up as a no-spark condition or a weak, inconsistent spark, which leads to hard starting, misfiring, surging, or stalling (often worse after the engine heats up). Confirm it by checking spark and ruling out simple ignition-kill issues first.
Quick symptoms checklist
- Engine cranks but will not start (especially with a known-good fuel supply)
- Starts cold but dies or won’t restart when hot
- Misfires, sputters, or surges under load
- Loses power in thicker grass, then recovers
- Intermittent spark (spark comes and goes)
- Backfiring through the muffler (less common, but possible)
Fast diagnosis steps (no special tools)
- Safety first: Disconnect the spark plug wire and keep hands clear of the blade area.
- Check the stop circuit: Make sure the operator presence control (bail/handle) is fully held. Inspect the kill wire for pinching or rubbed insulation.
- Verify spark: Remove the spark plug, reconnect it to the plug wire, ground the plug threads to clean metal on the engine, then pull the starter rope. You should see a strong blue snap.
- Try a known-good plug: A worn plug can mimic a bad coil. If spark returns with a fresh plug, the coil is not the problem.
More accurate test (spark tester and air gap)
A spark tester gives a clearer pass/fail than grounding a plug.
| Check | What “good” looks like | What points to a bad coil |
|---|---|---|
| Spark strength | Strong, consistent spark every pull | Weak, orange, or intermittent spark |
| Hot restart | Restarts normally after warming up | Loses spark when hot, returns after cooling |
| Coil air gap | Even gap to flywheel magnets | Gap too wide, coil shifted, or damaged |
Why it matters
The ignition coil creates the high voltage that fires the spark plug. When it breaks down (often from heat or age), the engine can act fuel-starved even when the carburetor and fuel system are fine.
Related parts to check while troubleshooting
These parts won’t fix a bad coil, but they commonly get inspected during no-start or poor-run complaints:
- Lawn & garden equipment engine spark plug 951-14437
- Lawn mower blade brake and clutch cable 946-04703A (a misadjusted or damaged control cable can affect run/stop behavior)
Last updated: February 2026
How old is my mower by serial number?
For a Craftsman CMXGMAM2703840 gas lawn mower, we determine age by reading the manufacturing date code on the mower’s ID label or by decoding the engine’s date code. The exact serial-number format varies by the manufacturer that built the mower, so the most reliable approach is to use the tag information and confirm with parts fit.
Where to find the serial and date information
Look for the model and serial label in these common spots:
- Rear of the deck (rear skirt area)
- Top of the deck near the engine mounting area
- Near a wheel height adjuster bracket
- Near the discharge opening (side or rear)
If the label is worn, take a clear photo and write down every character; one swapped digit can change the build family.
How to decode it (what to look for)
Instead of assuming one fixed pattern (like MMDDYY), use these checks:
- Look for an explicit “MFG DATE” or “DATE” field on the label
- Check for a separate date code printed near the serial number
- Use the engine code as a cross-check (engine shroud, valve cover area, or recoil housing)
- Confirm by matching installed parts to the CMXGMAM2703840 parts list
Quick cross-check table
| What you have | What it tells you | How we use it |
|---|---|---|
| Mower serial label date field | Mower build date | Best indicator of mower age |
| Engine date/manufacture code | Engine build date | Confirms timeframe; engine can be older than mower |
| Installed wear parts | Build family/version | Confirms correct parts breakdown |
A practical way to confirm you are working from the right build is to match a few common components, such as the lawn mower grass bag 664P05321A or the lawn mower blade brake and clutch cable 946-04703A, to what is installed on your mower.
Why it matters
Craftsman walk-behind mowers can have running changes within the same model number. Knowing the build timeframe helps ensure correct fit for blades, wheels, cables, and bagging or mulching components.
Last updated: February 2026
