Sufficient Clean Fuel
Figure 1. Diagnostic Form
The sufficient clean fuel procedure determines if the fuel system is getting sufficient clean fuel to start and operate the engine. For a reproduction of the applicable portion of the diagnostic form, see Figure
Follow this procedure to check for sufficient clean fuel to start and operate the engine:
- Obtain fuel sample from the fuel tank.
Note: Fuel must be of proper grade, clean and undiluted.
- Check for air in fuel: Check for leaks in the supply line from the tank to the fuel transfer pump. If in doubt, connect a piece of clear plastic tubing from the filter to the transfer pump inlet. Run the engine and watch for air bubbles. No air bubbles should be present.
Note: Cold weather can cause fuel waxing of certain grades of diesel fuel. This could result in fuel filter plugging.
- Check fuel odor for the presence of other fuels such as gasoline or kerosene.
- If engine oil is present in the fuel, it may indicate an injector O-ring leak and subsequent loss of injection control pressure. If that is suspected, perform the following:
- Drain some fuel from the fuel filter and check the color of the fuel. If the fuel appears darker in color, compare the fuel to a small quantity of newly purchased fuel to confirm contamination.
- If comparing the fuel is impossible or inconclusive, remove the fuel filter and cut the filter can using a filter cutter. If the filter element appears black, oil may have entered the fuel system past the injector O-rings.
- Check the injection control pressure during engine cranking. Use the Electronic Service Tool (EST) or follow the procedure outlined in part 9c of the Diagnostic Form. Refer to “10.14 Injection Control Pressure”
Note: If fuel quality is okay and the engine does not start, depress the priming valve plunger. If the plunger offers no resistance, it is an indication that fuel is not present in the system. Perform the fuel pump pressure test as outlined in 11 of the Diagnostic Form to check for fuel pressure. Refer to “10.16 Fuel Pump Pressure”
Low or No Fuel Possible Causes
Causes for low or no fuel follow:
- No fuel in tank.
- If equipped with an inline fuel valve, it is shut off.
- Fuel supply line from the tank(s) is broken or crimped.
- Fuel is waxed or jelled (most likely in cold weather with No. 2 fuel), the pickup tube in the tank is clogged or cracked. If there is excessive water in the tank, it is likely to freeze, preventing the fuel from being drawn to the engine.
- If the vehicle is equipped with supplemental filters or water separators, check for plugged filters or leakage that is allowing the fuel system to draw air.
- Cloudy fuel indicates that the fuel may not be a suitable grade for cold temperatures. Excessive water or contaminants in the fuel may indicate the tank and fuel need to be flushed and cleaned.
Clear container, approximately 1 quart.
|Series 40E Troubleshooting Manual – 6SE241|
|Generated on 10-13-2008|