Troubleshooting Common Combustion System Issues (and How to Fix Them Fast)

When your combustion system fails, whether it’s a sudden flameout or a loss of fuel, production grinds to a stop. Every minute of downtime hits your bottom line, so pinpointing the issue quickly and accurately is critical.

Even the best combustion systems run into problems, but most issues follow familiar patterns. With the right know-how, your maintenance team can diagnose and fix them efficiently, saving you from swapping out parts unnecessarily or calling in expensive technicians.

Here’s a practical guide from ECS field experts to help your team troubleshoot common combustion system issues fast, keeping your burners, fuel trains, and controls running smoothly and safely.

1. Flame Failure at Start-Up

Common Symptoms:

• Burner lights briefly, then shuts down
• No flame signal detected
• Lockout occurs during trial-for-ignition

Likely Causes:

• Dirty or misaligned flame sensor
• Weak ignition source (worn spark rod or transformer)
• Improper air-fuel ratio during light-off
• Blocked pilot orifice

Quick Fixes:

• Clean and reposition the flame rod; check wiring and grounding
• Inspect spark gap and replace ignition components if weak
• Adjust air damper to enrich the start-up mixture
• Verify pilot gas pressure and clean the pilot line

2. Unstable Flame or Pulsing Operation

Common Symptoms:

• Flame “hunts” or pulsates
• Audible rumbling or vibration
• Frequent lockouts during modulation

Likely Causes:

• Improper air-fuel ratio or tuning drift
• Worn linkages or actuator lag
• Sudden changes in load or fuel supply
• Blocked air inlet or flue

Quick Fixes:

• Retune the burner across the full load range
• Check actuator response and linkage integrity
• Inspect combustion air filters and blower performance
• Verify draft conditions and check for backpressure

3. Low or Inconsistent Gas Pressure

Common Symptoms:

• Burner trips at high fire
• Incomplete combustion or elevated CO levels
• Pressure switch faults or lockouts

Likely Causes:

• Clogged or undersized gas train components
• Regulator malfunction
• Upstream supply fluctuation
• Control valve positioning

Quick Fixes:

• Clean strainers and filters
• Verify regulator setpoints and performance
• Inspect main and vent valves for full stroke
• Compare live readings to pressure switch trip points

4. Frequent Lockouts Without Clear Cause

Common Symptoms:

• System locks out intermittently
• No consistent pattern to shutdowns
• Operators unsure how to respond

Likely Causes:

• Sensor noise or intermittent wiring issues
• Outdated flame safeguard logic
• External interlocks (fans, purge switches) dropping out
• Aging components such as relays or timers

Quick Fixes:

• Inspect and tighten wiring connections
• Log and interpret error codes from the controller
• Test interlocks for mechanical wear or drift
• Consider upgrading obsolete control hardware

5. Excessive Emissions or Failed Stack Test

Common Symptoms:

• High NOx or CO emissions
• Failed compliance or permit test
• Poor flame quality

Likely Causes:

• Air-fuel ratio drift or improper tuning
• Faulty oxygen sensor or trim controller
• Fouled burner nozzles
• Malfunctioning stack damper or draft control

Quick Fixes:

• Conduct a full burner tune-up
• Calibrate oxygen sensors and analyzers
• Clean burner nozzles and combustion chambers
• Verify damper and draft control performance

Final Tip: Start with the Basics

Before diving into advanced diagnostics, check these first:

• Wiring connections
• Sensor cleanliness and alignment
• Control panel fault logs
• Valve operation feedback
• Burner manuals and tuning curves

Most combustion system failures are mechanical or tuning-related, not catastrophic. By starting with these fundamentals, maintenance teams can resolve most issues quickly, safely, and without major disruption.

Partner with ECS for Expert Support

When problems go beyond quick fixes, Engineered Combustion Systems (ECS) provides expert diagnostics, field service, and retrofit solutions for complex combustion challenges. From flame safeguard upgrades to complete burner overhauls, our technicians help industrial operations minimize downtime and restore safe, efficient performance. Contact us today!