Your lawn mower cranks and cranks, maybe sputters a little on starting fluid, but just won’t stay running? If fuel isn’t reaching the engine, you’ll never get a clean start. This is one of the most common issues homeowners face, but it’s also one of the easiest to solve with a step-by-step approach. Here’s how to troubleshoot and fix a lawn mower when fuel isn’t getting to the engine.
Quick Picks: Most Common Reasons Fuel Isn’t Reaching the Engine
- Empty or Bad Gas: Tank is empty or gas has gone stale and won’t ignite.
- Clogged Fuel Filter: A dirty filter can block fuel flow to the carburetor.
- Blocked Fuel Line: Debris, gum, or old fuel can clog the fuel hose.
- Dirty or Gummed-Up Carburetor: Varnish from old fuel blocks jets and passages inside the carb.
- Fuel Shutoff Valve Closed: Some mowers have a manual shutoff—make sure it’s open.
- Faulty Fuel Pump (Riding Mowers): If the pump fails, no fuel is delivered to the carb.
- Vacuum Leaks or Cracked Primer Lines: If air gets in, the fuel system can lose suction.
- Vent Blocked in Gas Cap: If the cap vent is blocked, a vacuum can stop fuel flow.
Buyer’s Guide: What You’ll Need for Fuel System Troubleshooting
- Socket set & screwdrivers: For filter, hose, and carburetor access.
- Fuel line clamp or pliers: To safely disconnect hoses.
- Carburetor cleaner spray: For clearing gummed-up passages.
- Replacement fuel filter, hose, and clamps: If your old parts are blocked or brittle.
- New gasoline: Always use fuel less than 30 days old.
- Work gloves and rags: For safe, clean repairs.
- User manual: For filter location and diagrams.
Step-by-Step Guide: How to Fix Fuel Not Getting to Engine
1. Check for Fresh Fuel and Open Shutoff Valve
- Make sure there is fresh, clean gas in the tank.
- Find and turn the fuel shutoff valve (if equipped) to the “on” position.
2. Inspect the Fuel Filter
- Find the in-line fuel filter between the tank and carburetor.
- If it looks dirty, clogged, or is full of debris, replace it with the correct type for your mower.
3. Check the Fuel Line for Blockages or Kinks
- Disconnect the fuel line at the carburetor (use a clamp to stop leaks).
- Open the tank cap and check for strong fuel flow from the hose. If slow or none, the line may be blocked or kinked—clear or replace it as needed.
4. Inspect the Gas Cap Vent
- Remove the gas cap and try to start the mower. If it starts briefly with the cap off, the cap’s vent hole is likely blocked—clean or replace the cap.
5. Clean the Carburetor
- If gas reaches the carb but not the engine, the carburetor may be gummed up.
- Remove the air filter and spray carburetor cleaner into the carb intake.
- If possible, remove the carb and clean the jets and passages thoroughly. Reinstall and try again.
6. Check for Vacuum Leaks or Primer Issues
- Inspect primer bulbs and lines for cracks or loose connections.
- Replace any brittle or damaged hoses for proper suction.
7. Test the Fuel Pump (Riding Mowers)
- Follow your manual’s test procedure to see if the pump delivers fuel to the carb. Replace if faulty.
Comparison Table: Fuel Delivery Problems & Solutions
| Problem | Solution | Difficulty | Parts Needed |
|---|---|---|---|
| Clogged Fuel Filter | Replace filter | Easy | Fuel filter |
| Blocked Fuel Line | Clear/replace hose | Easy | Fuel hose |
| Dirty Carburetor | Clean/rebuild carb | Easy-Medium | Carb cleaner, gasket |
| Bad Fuel Pump | Replace pump | Medium | Fuel pump |
| Faulty Primer Bulb/Line | Replace bulb/hose | Easy | Primer bulb, hose |
| Blocked Gas Cap Vent | Clean/replace cap | Easy | Gas cap |
Frequently Asked Questions
How do I know if fuel is reaching the carburetor?
Disconnect the fuel line at the carburetor and check for a steady stream of fuel (with the cap off and valve open). No flow means a blockage in the tank, line, or filter.
Can a dirty carburetor prevent fuel from reaching the engine?
Absolutely. Gummed-up jets or sticky floats stop fuel from being drawn into the engine. A good cleaning usually fixes the problem.
Why does my mower start with starting fluid but won’t keep running?
This almost always means fuel isn’t reaching the combustion chamber—check the filter, lines, cap, and carburetor for blockages.
How do I prevent fuel delivery problems in the future?
Use fresh gas, replace filters regularly, clean the carburetor every season, and drain the tank/carb before winter storage.
Conclusion
If fuel isn’t getting to your lawn mower’s engine, the solution is usually simple—replace clogged filters or hoses, clean the carburetor, and check for blocked vents or valves. With a little maintenance, you’ll enjoy easy starts and reliable mowing all season long!