Carburetor Identification and Fuel System Notes for Michigan 75A Loader

[MikePhua]

Quick answer
The Michigan 75A loader, often powered by a Waukesha gasoline engine, typically uses a Marvel-Schebler TSX-series carburetor. Identifying the correct model requires matching the engine serial number and intake manifold configuration. Fuel delivery issues often stem from sediment bowl blockage, worn accelerator pumps, or incorrect float settings.
Michigan 75A loader background and engine options
The Michigan 75A was produced by Clark Equipment Company between the early 1960s and mid-1980s. It was a mid-sized wheel loader designed for municipal, industrial, and aggregate applications. The 75A came in both gasoline and diesel variants, with the gasoline version commonly equipped with a Waukesha 6-cylinder engine—either the 230 or 262 cubic inch model.
These engines were known for their torque and simplicity, but required regular maintenance of ignition and fuel systems. The carburetor played a central role in cold starts, throttle response, and load handling.
Typical carburetor models and identification
Most Waukesha-powered 75A loaders used a Marvel-Schebler TSX-series carburetor. Common variants include:

• TSX-422: Found on Waukesha 230 engines
  
• TSX-662: Used on later 262 engines
  
• TSX-813 or TSX-882: May appear on industrial variants with governor linkage
  

To identify the correct carburetor:

• Locate the stamped model number on the carburetor flange or body
  
• Cross-reference with Waukesha engine manuals or Clark parts catalogs
  
• Match throttle linkage and governor arm configuration
  

Some loaders were retrofitted with Zenith or Carter carburetors, especially in field repairs. These require custom linkage and may affect fuel-air ratios.
Fuel system layout and common issues
The fuel system includes:

• Gravity-fed tank or mechanical lift pump
  
• Sediment bowl with screen
  
• Inline fuel filter (optional)
  
• Carburetor with float bowl and accelerator pump
  

Common problems:

• Sediment bowl blockage: Rust and debris restrict flow, especially after long storage
  
• Float misadjustment: Causes flooding or starvation
  
• Worn accelerator pump: Leads to hesitation under load
  
• Vacuum leaks: At throttle shaft or intake gasket
  

One operator reported that his loader would start but stall under throttle. After inspecting the carburetor, he found the float needle stuck due to varnish buildup. Cleaning with carburetor solvent and replacing the gasket resolved the issue.
Rebuild kits and sourcing advice
Marvel-Schebler rebuild kits are available from vintage tractor suppliers and industrial parts vendors. A typical kit includes:

• Float needle and seat
  
• Accelerator pump diaphragm
  
• Gaskets and seals
  
• Main jet and idle mixture screw
  

Before ordering:

• Confirm the TSX model number
  
• Inspect throttle shaft wear—excess play may require bushing replacement
  
• Check for cracks in the cast body, especially near mounting flange
  

If the carburetor is missing or beyond repair, replacement units can be sourced from salvage yards or rebuilt by specialty shops. Some operators have successfully adapted farm tractor carburetors with similar CFM ratings.
Ignition and fuel synergy
Proper carburetor function depends on ignition timing and spark quality. Recommendations:

• Set timing to factory spec (usually 4–6° BTDC)
  
• Use non-resistor plugs for stronger spark
  
• Replace points and condenser every 200 hours
  
• Verify coil output and ballast resistor function
  

A misfiring engine may mimic carburetor problems, so always test ignition before adjusting fuel delivery.
Conclusion
The Michigan 75A loader’s gasoline variant relies on a Marvel-Schebler TSX-series carburetor matched to its Waukesha engine. Identifying the correct model and maintaining float, jet, and pump components are essential for reliable operation. With proper sourcing and rebuild techniques, even decades-old units can be restored to full functionality.