Cat IT28G Excessive Fuel Use & Smoking — Case Study & Troubleshooting

[MikePhua]

In a repair forum, an owner of a 2003 Cat IT28G tool carrier reported extremely high fuel consumption — around 5 gallons in 15 minutes — along with noticeable smoke. Such symptoms point to serious engine or fuel system malfunctions. Below is a synthesized, fully original analysis of likely causes, diagnostic steps, and preventive measures — blending technical reasoning with real-world anecdotes.
Machine & Engine Context
The Cat IT28G is a tool carrier / loader-style machine typically used for construction or site work. It often houses a Cat 3200 or 3300 series diesel engine or a model in that family, which is designed for heavy duty duty cycles and moderate loads. These engines rely on clean fuel, proper fueling pressure, intact injection systems, and good air intake. In good condition, they can run many thousands of hours if well maintained.
Because the owner claims extreme fuel burn and smoke, it's clear the machine is not operating in its normal efficiency envelope — something is forcing excessive fuel delivery, poor combustion, or both.
Symptoms & What They Imply

• 5 gallons in ≈15 minutes — That’s a fuel flow rate of about 20 gallons per hour, which is extremely high for a medium engine under moderate load. This suggests the engine is being flooded, running excessively rich, or burning in multiple cylinders inefficiently (incomplete combustion).
  
• Smoking (likely black smoke) — Black smoke usually signals unburned fuel, indicating overfueling, poor air supply (insufficient air), injector leakage, or clogged air system. Blue smoke (which was not emphasized) would suggest oil burning; white smoke might suggest coolant or other contamination.
  

From experience and community examples, such symptoms often trace back to fuel system faults, injector or pump malfunctions, or major air intake restrictions.
Common Causes & Plausible Faults

1. Fuel Injection System Faults
   • Leaking or stuck injectors delivering excessive fuel
     
   • Maladjusted injector timing or over-rich calibration
     
   • Faulty injection pump delivering too much fuel
     
   • Return lines restricted, causing overflow back into the rack instead of returning properly
     
2. Air Intake / Turbo / Filter Issues
   • Massive restriction in air filter or intake path, starving the engine of air and making combustion inefficient
     
   • Turbocharger failure (worn bearings, leaking seals) reducing boost pressure
     
   • Intercooler or charge piping leaks, dumping air and upsetting air/fuel ratio
     
3. Engine Mechanical Problems
   • Head gasket failure allowing cross-flow, causing misfires or extra fuel demand
     
   • Cylinder compression loss or piston ring wear causing inefficient combustion
     
   • Overheating from cooling system issues leading to fuel demands rising to maintain power
     
4. Fuel Quality / Contamination / Air in Fuel Lines
   • Dirty or contaminated fuel causing injectors to behave erratically
     
   • Water in fuel causing misfire or poor combustion, forcing more fuel
     
   • Air intrusion (leaks) in the fuel supply side causing pump or injectors to compensate with extra fuel
     
5. Overload or Misuse
   • Operating at extremely heavy load beyond design limits
     
   • Excessive idling or cycling under partial loads that reduce efficiency
     
   • Operator technique (full throttle constantly, poor gear match) exacerbating fuel consumption
     

Diagnostic Steps & Checks
Below is a prioritized checklist you or a mechanic should follow:

• Injectors & Pump Check: Remove injectors and inspect spray patterns. Swap injectors among cylinders to see if smoking or fuel consumption changes.
  
• Fuel Pressure & Pump Calibration: Measure fuel pressure in the line from pump to injectors and compare to spec. A pump set too rich or over delivering is a red flag.
  
• Air Intake Inspection: Remove/inspect air filter, check for blockages, inspect turbo compressor side, examine hoses for leaks or collapsed sections.
  
• Smoke Color & Behavior: Black smoke on load suggests overfuelling. If smoke persists under no load, injection system likely fault.
  
• Cylinder Compression Test: Check if all cylinders hold proper compression. A failing cylinder may cause imbalance.
  
• Fuel Return / Overflow Lines: Check for blockages in return lines. Ensure fuel isn’t recirculating improperly.
  
• Cooling System & Overheating: Monitor coolant temperature, check radiator airflow, ensure all thermostats, water pump are functioning. Overheating forces engines to burn more fuel.
  
• Fuel Quality & Contaminants: Drain at bottom of tank, test for water or sediment, replace filters, flush lines if needed.
  
• Exhaust Restrictions: A clogged muffler or DPF (if equipped) can cause back pressure, increasing fuel use.
  

Real-World Anecdotes
An owner elsewhere reported a similar symptom on a Cat 3204 DI engine: after filter replacement and air in line, the machine would start but stall. Another user in a separate community had an IT28 running on just two cylinders, producing smoke; the solution turned out to be blown head gasket between those cylinders. These stories underscore that fuel/air mismatch or mechanical damage are frequent culprits.
Corrective & Preventive Measures

• Replace injectors in sets if irregular performance or leakage is detected
  
• Use fresh, clean fuel and fuel filters matching spec
  
• Maintain air system and turbo, ensure no intake restriction
  
• Regular compression checks and proactive engine overhaul as hours accumulate
  
• Avoid persistent overloading or misuse
  
• Monitor fuel consumption and smoke regularly as an early indicator of drift
  
• If calibration or pump settings are off, have a qualified service shop reprogram or recalibrate
  

Conclusion
An IT28G burning fuel at such an extreme rate and producing smoke is symptomatic of a major fault — likely in injection, air supply, or internal wear. With careful diagnosis using the checklist above, most causes can be found. A machine in fair condition should not burn 20 gal/hr, so aggressive investigation and repair are well justified. If you like, send me more engine model data and any diagnostic readings (fuel pressure, compression), and I’ll help narrow further.