Identify the type of smoke first
The KTA19 is a 19-litre inline-six widely used as a marine main or auxiliary engine. Black smoke means incomplete combustion, so start by classifying when it appears:
- Only during acceleration — fuel response versus turbo lag; usually transient.
- Continuous under load — look for insufficient air or poor atomisation.
- Cold engine only — low-temperature combustion; check preheat and thermostats.
Five components to check first
1. Fuel filters and water separator
A restricted filter reduces supply and atomisation quality. Replace by hours rather than waiting for a blockage alarm, and always bleed the system afterwards.
2. Injectors
Poor atomisation, dribbling or excessive return flow all produce black smoke. Test opening pressure and spray pattern on a bench; a simple cylinder cut-out test is not enough to condemn or clear an injector.
3. PT fuel pump and governor
PT pump delivery and timing set the air-fuel ratio. Check throttle linkage travel and whether idle or full-load fuel settings have been altered. Do not dismantle the pump without the right test stand.
4. Fuel supply pump and lines
High inlet restriction, air ingress or excessive return back-pressure all move actual delivery away from the setting. Inspect ageing hoses, fittings and the tank pick-up for air.
5. Turbocharger and aftercooler
Low boost with normal fuel is the classic black-smoke combination. Check impeller clearance, wastegate operation, aftercooler restriction or leaks, and hose clamps on the intake path.
When to replace instead of adjust
- Injector spray pattern deformed or dribbling with no adjustment possible.
- Turbo impeller rubbing the housing, excessive axial play, or oil entering the intake.
- PT pump cam chamber wear with delivery drifting as temperature changes.
- Aftercooler core blocked or pressure drop out of specification.
Prevention on board
Keeping the air and fuel paths clean is cheaper than replacing parts: filters on schedule, regular tank draining, and a quarterly check of intake clamps and hoses. For KTA19 injectors, PT pump parts, turbochargers and filters, see Marine Turbocharger and Marine Filter, or contact us with your engine model and symptoms.