Graham FisherBy Graham Fisher

Updated November 2026

When a Remington 159cc lawn mower won’t start, the problem is almost always one of a handful of things: stale or missing fuel, a fouled or disconnected spark plug, a clogged air filter, a choke or throttle set wrong, or a carburetor gummed up from old gas. This guide walks through those causes in the order that is easiest to check, so you can work through them without tearing the engine apart. Most owners can resolve the issue in under an hour with basic hand tools.

Before You Start: Safety First

Before you touch anything near the blade or engine, disconnect the spark plug wire and make sure the mower is on level ground with the fuel shutoff in a known position. Remove the key if your model has one. Work with the engine cool, since the muffler and cylinder head can cause serious burns shortly after running. If you are unsure about fuel system or carburetor work, or if you smell raw gas or see leaks, consult a qualified small-engine repair technician.

Shopping for one? See our guide: Lawn Mower Won't Start Without Starter Fluid: 5 Best Options Compared.

Step 1: Check the Fuel

Fuel is the cause in more no-start situations than any other single factor. Gasoline that sits for more than about 30 days begins to break down, leaving varnish and gum in the fuel system. Ethanol-blended gas also attracts moisture over time, which can cause the engine to run rough or refuse to fire.

What to look for

  • Fuel tank that is empty or low on fuel
  • Gas that is dark, smells sour, or has visible debris or water
  • Fuel line that is cracked, brittle, or collapsed
  • Primer bulb (if equipped) that stays flat when pressed

What to do

  1. Drain the old fuel into an approved container and dispose of it at a local hazardous waste facility.
  2. Refill with fresh unleaded gasoline. Many small-engine makers recommend fuel with no more than 10 percent ethanol, and some specify a minimum octane rating, so check the owner’s manual.
  3. Prime the engine by pressing the primer bulb about 5 to 10 times, if your model has one.

Step 2: Inspect the Spark Plug

A spark plug that is dirty, wet, or loose will prevent combustion even when fuel and air are present. Pull the plug with a spark plug socket and inspect the tip.

Reading the plug

Condition What it usually means Action
Black, sooty tip and electrode Rich fuel mixture or dirty air filter Clean or replace the plug; check the air filter
Wet, fuel-soaked tip Flooding from over-priming or choke left on Dry the plug, leave it out, crank the engine to clear fuel
White or blistered insulator Lean mixture or overheating Replace the plug; check for air leaks
Cracked porcelain or worn electrode End of service life Replace with the plug specified in the manual

Set the gap to the value listed in your owner’s manual, typically around 0.030 inch for many small Briggs-type engines, though you should confirm the exact specification for your model. Reinstall the plug finger-tight, then snug it with the socket about a quarter turn beyond seating. Reconnect the wire firmly until it clicks.

Step 3: Check the Air Filter

The air filter keeps dust and grass clippings out of the carburetor. When it is clogged, the engine receives too much fuel relative to air, which causes hard starting, sputtering, and black plugs. Remove the cover, pull the filter, and inspect it. Paper elements should be replaced if they are visibly dirty. Foam elements can be washed in warm soapy water, squeezed dry, and lightly oiled with engine oil.

Step 4: Set the Choke and Throttle Correctly

Starting procedure is a frequent culprit, especially on a cold engine. For a cold start, the choke is usually closed (or set to “start”) and the throttle is set about halfway between idle and fast. For a warm restart, the choke is typically open and the throttle is set to fast. Flooding happens when the choke stays closed on a warm engine, so if the mower smells of fuel and the plug is wet, let the engine sit for 10 to 15 minutes before trying again with the choke open.

Step 5: Look for a Clogged or Gummed Carburetor

If fuel is fresh and the plug is dry and firing, the carburetor may be blocked by varnish or debris from old gas. Symptoms include an engine that starts briefly and dies, runs only with the choke engaged, or idles poorly. Cleaning the carburetor involves removing the bowl, cleaning the jets and passages with carburetor cleaner, and checking the float and needle valve. This is one of the more involved repairs, so take your time and photograph the linkage before disassembly.

Sub-steps for a carburetor cleaning

  1. Disconnect the fuel line and remove the air filter housing.
  2. Take off the carburetor bowl and note the gasket position.
  3. Spray carburetor cleaner through the jets and passages. Do not use wire that could scratch the calibrated openings.
  4. Reassemble with new gaskets if the old ones are hardened, and confirm the float sits level.

Step 6: Verify the Safety Features

Most walk-behind mowers will not crank unless certain conditions are met. Check that the blade control or bail bar is engaged properly, that the operator presence control is depressed, and that the wheel-drive or transmission lever is in neutral if applicable. A loose or misadjusted safety switch can prevent the starter from engaging even when the engine itself is healthy.

Step 7: Check the Battery and Starter (Electric-Start Models)

If your Remington has electric start, a weak battery will produce a slow crank or a single click. Test the battery voltage with a multimeter; a healthy 12-volt battery should read above roughly 12.4 volts at rest. Clean the terminals and confirm the ground connection to the engine block. If you hear a click but no cranking, the starter solenoid or starter motor may need attention.

Tools and Supplies You May Need

  • Spark plug socket and ratchet
  • Feeler gauge for checking plug gap
  • Screwdriver set and small socket set
  • Fresh unleaded gasoline and an approved fuel container
  • Carburetor cleaner and clean rags
  • Multimeter for battery testing

A fresh spark plug matched to the engine and a fuel stabilizer for storage will prevent most recurring no-start problems. A small gap tool and a basic multimeter make the inspection steps faster and more accurate.

  • NGK spark plug — Provides a reliable replacement with the correct heat range for many small engines. View on Amazon
  • Sta-Bil fuel stabilizer — Helps prevent gum and varnish formation when gas sits in the tank over winter. View on Amazon
  • Digital multimeter — Lets you check battery voltage and continuity on electric-start models. View on Amazon
  • Carburetor cleaner spray — Dissolves varnish in jets and passages during a cleaning. View on Amazon

Common Mistakes

  • Repeatedly cranking a flooded engine instead of drying the plug and letting it rest.
  • Leaving old gas in the tank over winter and expecting it to start in spring.
  • Replacing the spark plug without first checking the fuel, which is the more likely cause.
  • Using a plug with the wrong heat range or thread size.
  • Forgetting to reconnect the spark plug wire after maintenance.

Tips for Preventing Future Starting Problems

Add fuel stabilizer to every tank of gas you plan to store for more than a few weeks, or run the carburetor dry before long storage periods. Change the air filter at the intervals in your manual, and replace the spark plug at least once per season or every 100 hours of use. Keep the deck clean of grass, since clippings packed around the engine can trap heat and accelerate wear.

FAQ

Why does my Remington 159cc mower start and then die?

This usually points to a fuel delivery problem, such as a partially clogged carburetor jet, a restricted fuel line, or a dirty air filter starving the engine. Check fuel freshness first, then inspect the carburetor if the problem continues.

How much fuel should I put in the Remington before starting?

Fill the tank with fresh unleaded gasoline to the level indicated on the tank. Overfilling can cause fuel to leak into the air filter or onto the engine.

Can I use gas with ethanol in my Remington mower?

Many small-engine manufacturers recommend gasoline with 10 percent ethanol or less. Higher blends can damage fuel system components. Check your owner’s manual for the specific limit.

How often should I replace the spark plug?

Many owners replace the plug annually or after about 100 hours of operation. Inspect it at each season change and replace it sooner if the electrode is worn or the insulator is cracked.

What does a black, sooty spark plug indicate?

A black, sooty plug usually means the engine is running rich, often because of a dirty air filter, a stuck choke, or a carburetor issue. Address the air and fuel mixture before simply replacing the plug.

Should I drain the gas before storing the mower?

For storage longer than a month, either drain the tank and run the engine until the carburetor is empty, or add a fuel stabilizer and run the engine for a few minutes so treated fuel reaches the carburetor.

When should I call a professional?

If you have checked the fuel, plug, air filter, and choke without success, or if you find cracked fuel lines, fuel leaks, or electrical damage, a qualified small-engine technician can diagnose the issue safely.

Conclusion

Most Remington 159cc no-start problems come down to fuel, spark, air, or the choke, and working through them in that order is the fastest route to a running mower. Start with fresh gas and a clean, dry plug before moving to the carburetor. Keep up with seasonal maintenance and a fuel stabilizer, and the mower should start reliably when you need it.

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Graham Fisher

About Graham Fisher

Graham Fisher is part of our editorial team and reviews and edits our lawn mowers guides, checking product details against manufacturer specifications and owner feedback.