Fuel System Operation and Tests
FUEL SUPPLY QUALITY CHECK
NOTE: Illustration shows fuel supply pump on engines
with rotary injection pumps. On engines with
in-line injection pumps, the supply pump is
mounted on the side of the injection pump. The
following procedure is the same for both.
The quality of diesel fuel affects engine performance.
Check your operators manual for correct fuel
Poor quality or contaminated fuel will make the engine
hard to start, misfire, run rough or produce low power.
If poor quality or contaminated fuel is suspected, perform
1. Check primary (if equipped) and final fuel filters for
servicability. If filter is equipped with with a water
separator, empty and clean separator bowl.
2. Start engine and operate under load, observing engine
3. Disconnect fuel line from inlet side of primary fuel filter
(if equipped) or inlet side of supply pump on engines
without primary filter.
4. Connect a hose to inlet port.
5. Submerge hose in a container of clean, good quality
fuel meeting engine specifications.
6. Operate engine under load and observe performance.
If performance improves, fuel is contaminated or not of
the proper grade. Check fuel source.