As the engine warms-up the WRD leans the fuel mixture as you probably know. So hot starts happen at the leanest engine cycle. This typically can add to hot start problems. Now if there is any other contributions to lean running during this period, the problem can be severe. First, all starting aids have to be functioning correctly during this period. Any other factors causing lean running must be corrected. Basic setting of the injection system "too lean" will aggravate the problem. Check engine during warm running with the split linkage test.
Low fuel pressure can be another item causing lean running. As fuel pressure drops, the system leans out. Problems which may cause low fuel pressure can be: a clogged delivery system (tank screen, defective elec. fuel pump or clogged screen in fuel pump, clogged main filter, or improper connection of fuel lines at IP or inoperative fuel regulator/check valve. Fuel pressure effects critical fuel volume, and circulation also. Large volume of fuel continually circulates through the system Starting at the fuel tank, and returning to the fuel tank. This continuous volume of fuel cools the IP and the fuel itself as it circulates. If the fuel volume or pressure is low, the fuel system will become leaner. and hotter. Fuel can actually boil or vapor lock in the IP or the injector lines in severe cases. Good fuel volume and pressure during start up, helps clear the lines and cool the fuel system. This is why a plugged fuel return line can cause sever starting problems, since the fuel cannot circulate or cool the system. Dan C. has suggested that the "swirl effect" in the fuel tank "flower pot", actually contributes to the fuel cooling. This makes sense.
If you are not using an original electric fuel pump, and the replacement is not up to specs, this may be your issue, even though the engine runs fine. Starting problems, especially when hot, are a sign that the after-market elec. fuel pump, may not be up to the task.
If the check valve/reg. at the IP is not functioning correctly the pressure may be too low or it may not be allowing fuel to return to the tank. This will cause the fuel system to run warm, cause vapor locking and hard hot starting.
Identify which starting aids are used on your engine. Look at the chart and information in the "starting aid tour". Make sure your system is operating as it should. Some systems use the starting aids during warm and cold starting.
The CSV on the intake can become clogged. Some have a fine fuel screen built in the intake fitting, clear it. Sometimes the fuel jet itself becomes restricted, clear it. Test the functioning of the electric solenoid on the CSV and the injection pump.
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