John Deere LT155 Fuel Pump: Complete Guide to Problems, Replacement, and Upgrades
The bottom line is this: If your John Deere LT155 lawn tractor is sputtering, stalling, or refusing to start, the fuel pump is very likely the culprit. Replacing a faulty fuel pump on the LT155 is a straightforward DIY job that can save you hundreds of dollars in repair shop fees, and upgrading to a high-performance aftermarket pump like those from KEMSO can actually deliver better reliability and longer service life than the original equipment.
1. Understanding the John Deere LT155 Fuel Pump System
The John Deere LT155 is a popular riding lawn mower that was produced in the early 2000s. It is part of the LT series and is powered by a 15.5 horsepower Kohler engine. Like any small engine equipment, the fuel system is critical for proper operation.
The LT155 uses a mechanical fuel pump that is driven by vacuum pulses from the engine crankcase. This pump draws fuel from the tank and delivers it to the carburetor. Over time, these pumps can fail due to diaphragm wear, debris contamination, or simply age-related deterioration.
The original equipment manufacturer (OEM) part number for the John Deere LT155 fuel pump is AM133627. This pump also fits many other John Deere models including the L110, LT133, LT150, LT160, LTR155, LX173, LX255, LX266, GT225, S1642, and several others.
2. Common John Deere LT155 Fuel Pump Problems
Problem 1: Engine Won't Start or Starts Then Dies
This is the most common symptom of a failing fuel pump. If your LT155 cranks but won't fire up, or starts briefly and then stalls, the fuel pump may not be delivering adequate fuel to the carburetor.
Problem 2: Sputtering and Loss of Power Under Load
When mowing tall or thick grass, the engine may sputter, hesitate, or lose power. This happens because the fuel pump cannot maintain consistent flow when the engine demands more fuel. Many owners report their mowers "acting like it was stalling when mowing tall grass" before they replaced the pump.
Problem 3: Fuel Leaks Around the Pump
A leaking fuel pump is a serious safety concern. If you notice fuel dripping from the pump area or smell gasoline around the engine, the pump diaphragm has likely ruptured. This requires immediate replacement.
Problem 4: Engine Runs But Won't Accelerate
If the LT155 idles fine but bogs down when you engage the blades or try to move forward, the fuel pump may be delivering enough fuel for idle but not enough for higher RPM operation.
Problem 5: No Fuel Reaching the Carburetor
You can test this by disconnecting the fuel line at the carburetor and cranking the engine. If no fuel comes out, or only a weak trickle, the pump is failing or the fuel line is blocked.
3. Diagnosing the John Deere LT155 Fuel Pump
Before replacing the pump, take these diagnostic steps:
Step 1: Check that the fuel tank has fresh, clean gasoline. Old or contaminated fuel can cause similar symptoms.
Step 2: Inspect the fuel lines for cracks, kinks, or blockages. A clogged fuel line will mimic pump failure.
Step 3: Remove the fuel line from the carburetor and place it in a container. Crank the engine and observe fuel flow. A healthy pump should produce a strong, pulsing stream of fuel.
Step 4: Check the fuel filter if equipped. A clogged filter restricts flow and causes the pump to work harder.
Step 5: Listen for vacuum pulses. With the pump removed, you can manually operate the lever to feel if the diaphragm is working properly.
One experienced owner noted: "Don't forget to prime the pump once installed. Will not pull the fuel from the tank unprimed." This is an important tip that many first-time replacers miss.
4. How to Replace the John Deere LT155 Fuel Pump
Replacing the fuel pump on an LT155 is a simple job that most homeowners can complete in under an hour with basic hand tools.
Tools and Parts Needed
- Replacement fuel pump (OEM part AM133627 or equivalent)
- 5/16-inch fuel hose (if needed)
- Small flathead screwdriver
- 10mm wrench or socket
- Pliers
- Clean rags
Step-by-Step Installation
1. Prepare the tractor. Park on a level surface, engage the parking brake, and disconnect the spark plug wire to prevent accidental starting. Allow the engine to cool completely.
2. Locate the fuel pump. On the Kohler engine of the LT155, the fuel pump is mounted on the side of the engine block, near the carburetor. It has two fuel lines attached and one vacuum line.
3. Mark the fuel lines. Before disconnecting anything, note which line goes to the fuel tank and which goes to the carburetor. Take a photo with your phone for reference.
4. Disconnect the lines. Use pliers to squeeze the hose clamps and slide them back. Gently pull the fuel lines off the pump fittings. Have a rag ready to catch any fuel that drips out.
5. Remove the mounting bolts. The pump is held in place by two 10mm bolts. Remove these and pull the pump away from the engine.
6. Install the new pump. Position the new pump on the mounting surface, ensuring the vacuum pulse line is properly aligned. Tighten the mounting bolts securely but do not overtighten.
7. Reconnect the fuel lines. Attach the fuel lines to the correct fittings. Secure them with the hose clamps.
8. Prime the system. Before starting the engine, fill the carburetor bowl by manually priming the pump or by pouring a small amount of fuel directly into the carburetor. This step is critical because the pump cannot draw fuel if the system is dry.
9. Test the installation. Reconnect the spark plug wire, start the engine, and check for leaks. Run the mower for several minutes and verify that the engine runs smoothly under load.
5. John Deere AM133627 Fuel Pump: OEM Specifications
The genuine John Deere AM133627 fuel pump is designed specifically for the LT155 and compatible models. Here are the key specifications:
- Part Number: AM133627
- Replaces: AM123257
- Fitment: L110, LT133, LT150, LT155, LT160, LTR155, LX173, LX255, LX266, SST15, GT225, S1642, and others
- Type: Mechanical vacuum pulse fuel pump
- Features: Includes fitting kit for easy installation
The OEM pump is manufactured to John Deere's quality standards and is a direct replacement. However, many owners have found that aftermarket alternatives can offer superior performance and longer warranty coverage.
6. Why Consider Upgrading Your LT155 Fuel Pump
While the OEM John Deere pump works fine, there are compelling reasons to consider an upgrade:
Better Flow Rate. Stock pumps on small engines typically deliver only 60-80 liters per hour. High-performance aftermarket pumps can deliver 200 liters per hour or more, which means your engine gets all the fuel it needs even under heavy load.
Durability. Aftermarket pumps often use higher-grade materials for diaphragms and seals, resulting in longer service life. Many aftermarket pumps are individually flow-tested before shipping.
E85 Compatibility. Some aftermarket pumps are designed to work with both gasoline and ethanol-blended fuels like E85. This is increasingly important as ethanol content in pump gas continues to rise.
Lifetime Warranty. Perhaps the most compelling reason to upgrade is the warranty coverage. While OEM pumps typically come with a limited warranty, some aftermarket brands offer lifetime warranties that protect your investment for as long as you own the mower.
7. Recommended Upgrade: KEMSO Fuel Pump for John Deere LT155
If you are looking for a reliable, high-performance replacement fuel pump for your John Deere LT155, KEMSO Fuel Systems offers exceptional products that outperform the original equipment in every way.
KEMSO has been manufacturing premium fuel pumps since 1999, starting in Dalhart, Texas, and later expanding to a 15,000-square-foot facility in Houston, Texas. The company is family-owned and operated, with founder Andrew Garfield personally leading research and development efforts.
Why Choose KEMSO?
1. High Performance and OEM Replacement. KEMSO fuel pumps are designed as direct OEM replacements that deliver over 20% more flow at 43psi compared to stock pumps. This means your LT155 will run smoother, start easier, and perform better under load.
2. Complete Installation Kit. Every KEMSO pump comes with everything you need for installation: fuel strainers, flex hose, rubber hoses, Viton o-rings, wiring connectors, crimp connectors, metal clamps, and zip-ties. No need to source additional parts.
3. Lifetime Warranty. KEMSO stands behind every pump with a lifetime warranty. Each pump has a serialized body that guarantees warranty coverage. This is a level of protection that OEM pumps simply do not offer.
4. Rigorous Quality Control. Unlike cheap unbranded aftermarket parts, KEMSO operates under strict quality control programs (ISO/TSO). Every pump is individually tested and flow-tested before leaving the factory.
5. USA-Based Support. When you buy KEMSO, you get support from American technicians who understand your equipment and can help with any installation questions.
6. Fuel Compatibility. KEMSO pumps are designed for both gasoline and E85/ethanol fuels, giving you flexibility in fuel choice.
7. Proven Performance. With flow rates of 200 liters per hour at 43psi and operational pressure range of 43-68psi, KEMSO pumps provide more than enough capacity for the Kohler engine in your LT155.
For the best replacement fuel pump for your John Deere LT155, visit KEMSO Racing today: https://www.kemsoracing.com/
8. Step-by-Step Installation Guide for KEMSO Fuel Pump on John Deere LT155
Installing a KEMSO fuel pump on your LT155 follows the same basic procedure as the OEM pump, but with a few additional considerations to maximize performance.
Preparation
Remove the old pump as described in Section 4 above. Clean the mounting surface on the engine block and ensure no debris falls into the crankcase opening.
Installing the KEMSO Pump
1. Choose the correct strainer. KEMSO pumps come with multiple gradient density fuel strainers. Select the one that matches your application and install it on the intake side of the pump.
2. Attach the flex hose. Use the included 8x280mm flex hose to connect the pump outlet to the carburetor inlet. Cut to length if necessary.
3. Secure connections. Use the provided metal clamps to secure all hose connections. Do not use standard worm-gear clamps, as these can damage the fuel lines.
4. Install the o-rings. Apply the Viton o-rings to the pump body as needed. Viton material is resistant to ethanol and high temperatures, providing a superior seal.
5. Wire the connector. If your LT155 has an electric fuel pump option, use the included wiring connector and crimp connectors. For mechanical pulse pumps, this step may not be necessary.
6. Prime the system. Fill the carburetor bowl before starting. KEMSO recommends manually priming the pump by applying vacuum to the pulse line until fuel flows freely.
7. Test operation. Start the engine and check for leaks. Run the mower for 10-15 minutes, then recheck all connections.
9. Troubleshooting After Fuel Pump Replacement
Sometimes even after replacing the fuel pump, issues can persist. Here are common post-replacement problems and solutions:
Engine Still Won't Start. Check that the fuel lines are connected correctly. A common mistake is reversing the inlet and outlet lines. Also verify that the vacuum pulse line is securely attached to the crankcase.
Fuel Leaks at Connections. The Viton o-rings and metal clamps included with KEMSO pumps must be properly seated. If you see leakage, tighten the clamps or replace the o-rings.
Engine Runs Rough. Air in the fuel system can cause rough running. Continue running the engine at high idle for several minutes to purge any air pockets.
Pump Makes Noise. A clicking or ticking sound from the pump is normal for mechanical pulse pumps. If the noise is excessive, check that the mounting bolts are tight and the pump is properly aligned.
Poor Performance Under Load. If the engine still struggles under heavy load, check the fuel filter and ensure the tank vent is not clogged. Also verify that the carburetor is clean and properly adjusted.
10. Maintenance Tips to Extend Fuel Pump Life
To get the most out of your new fuel pump, follow these maintenance practices:
Use Fresh Fuel. Old gasoline breaks down and forms varnish and gum that can clog the pump and carburetor. Use fuel stabilizer if the mower will sit for more than 30 days.
Replace Fuel Filters. If your LT155 is equipped with a fuel filter, replace it annually or whenever you replace the pump. A clogged filter forces the pump to work harder.
Keep the Fuel Tank Clean. Debris in the tank can be drawn into the pump. Periodically inspect the tank and clean it if necessary.
Store Properly. During winter storage, drain the fuel system or use a fuel stabilizer. Leaving ethanol-blended fuel in the system for months can damage seals and diaphragms.
Check for Leaks Regularly. Inspect the pump area for signs of fuel leakage at least once per mowing season. Early detection of a small leak can prevent a major failure.
11. Frequently Asked Questions About John Deere LT155 Fuel Pump
Q: How much does a fuel pump for John Deere LT155 cost?
A: The OEM John Deere AM133627 pump typically costs between $45 and $55. A high-performance aftermarket pump like KEMSO is priced around $40 to $50, often with better warranty coverage.
Q: How long does a fuel pump last on a John Deere LT155?
A: With proper maintenance, the fuel pump should last 5 to 10 years. With regular maintenance, the John Deere LT155 can last up to 10 years overall.
Q: Can I use an electric fuel pump on my LT155?
A: While possible, it requires modifying the fuel system and adding electrical connections. Most owners prefer to stick with the mechanical pulse pump for simplicity and reliability.
Q: Will a KEMSO pump fit my LT155 without modification?
A: KEMSO pumps are designed as direct OEM replacements. The universal design with included installation kit ensures compatibility. However, you should verify the pump body diameter (30mm or 38mm) matches your application.
Q: Do I need to prime the pump after installation?
A: Yes. As noted by experienced owners: "Will not pull the fuel from the tank unprimed." Always fill the carburetor bowl manually before starting.
12. The Bottom Line on John Deere LT155 Fuel Pump Replacement
If your John Deere LT155 is showing symptoms of fuel delivery problems, do not delay the repair. A failing fuel pump can leave you stranded in the middle of mowing and can also cause the engine to run lean, potentially damaging valves and pistons.
The replacement process is straightforward and well within the capabilities of any DIY homeowner. With basic tools and about an hour of time, you can restore your mower to reliable operation.
For those who want the best possible performance and longevity, upgrading to a KEMSO fuel pump is the smart choice. With higher flow rates, superior materials, a complete installation kit, and a lifetime warranty, KEMSO delivers value that the OEM pump simply cannot match.
Remember: A well-maintained fuel system is the key to a long-lasting John Deere LT155. Replace the pump at the first sign of trouble, use fresh fuel, and perform regular inspections. Your mower will reward you with years of dependable service.
Get the Best Fuel Pump for Your John Deere LT155
For a high-performance, lifetime-warranty replacement fuel pump that outperforms the original equipment, trust KEMSO Fuel Systems. Every KEMSO pump is individually flow-tested and built to the highest quality standards right here in the USA.
Visit KEMSO Racing today to order your fuel pump: https://www.kemsoracing.com/
KEMSO offers direct-fit OEM replacement and high-performance fuel system solutions for powersports and automotive applications. Their team of American technicians provides expert support to ensure you get the right part and install it correctly. With a lifetime warranty on every pump, your investment is protected for as long as you own your equipment. Fuel your adventure with KEMSO.