My 930 doesn't start when it is warm

[abdulcito]

Hi friends, my 930 1979 starts very well when it is cold, but when it is warm, starts very well immediately after turn off, but after 5 minutes starts so so hard, some times I need to push the screw over the plate with the switch on.

I changed both pumps, the fuel filter but nothing.

Can you help me please !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Thanks

[mark houghton]

This is a pretty common question lately. First guess is fuel accumulator malfunctioning, second is fuel injectors allowing fuel to seep into the engine when shut down and basically flooding it. Other things can be WUR malfunction, or....here are a few that you may also want to look at (Google results for K-Jetronic troubleshooting - pretty generic):

Hot Starting Difficulty

1) Loss of rest pressure;
Perform a pressure test and focus on the rest pressure.If it does not pass,check for a defective fuel pump check valve,defective fuel distributor,faulty system pressure regulator and leaking cold start injector.

2) Airflow sensor improperly adjusted;
Check height,centering and for binding. Loosen the center line on the fuel distributor to relieve control pressure.

3) Sticking or binding control plunger;
Remove the fuel distributor and ensure that the control plunger moves freely.

4) Injectors leaking;
Remove the injectors from the intake manifold and with the ignition key on and engine NOT running,press on the center plate to pressurize the system.Inspect and replace any injectors that are leaking.

5) Cold start injector leaking;
Same test as above.

6) Shorted thermo-time switch;
Cold start injector is dependant on this component functioning.

7) Incorrect control pressure;
Perform a pressure test and verify that the warm control is within specs