Modern diesel fuel systems operate at pressures up to 35,000 PSI—enough to cut through steel.

At these pressures, even microscopic debris or a drop of water can act like a bullet to your fuel injectors.

Problem Overview

Engine misfiring, hard starting when warm, and excessive black or white smoke are primary indicators of fuel system distress.

Sudden engine shutdown while driving often points to a loss of rail pressure or a failed high-pressure pump.

Common Causes

Contaminated fuel containing water, sediment, or incorrect additives.

Leaking fuel injectors 'washing' the cylinder walls and causing oil dilution.

Failed fuel pressure regulator allowing pressure to spike or drop uncontrollably.

Air being drawn into the low-pressure side of the system through a cracked line or seal.

Change both the primary and secondary fuel filters every 10,000 miles in dusty or wet conditions.

Drain the water-separator daily—don't wait for the dash light to come on.

Use a diagnostic tool to perform a 'cylinder contribution' test to identify weak injectors.

Perform a 'return flow' test on the injectors to check for excessive internal leakage.

Never loosen a fuel line while the engine is running or recently shut down; the pressure can kill.

Buy fuel from high-volume truck stops to ensure the fuel is fresh and free of settled contaminants.

If you suspect water in your fuel, stop the engine immediately to prevent destroying the injectors.

If your 'Water in Fuel' light stays on after draining the separator.

When the truck will only run on starting fluid (and then dies)—do NOT keep spraying ether.

If you have a massive fuel leak on the high-pressure side that creates a fine mist of diesel.

Clean fuel is the only way to get 500,000+ miles out of modern injectors.

An extra $50 on high-quality filters saves $5,000 on a set of injectors.

Fuel issues holding you back? Our mobile diesel technicians specialize in common rail diagnostics and on-site injector services.