Injector leak or ECU failure?

[DKneble]

I have been having some hard starting issues with my car for the last couple months which led me to test pretty much every sensor and every possible source that I could think of including compression testing, leak down testing, replacing all the ignition sensors, tps, CAS, etc.

If I shut the car off and let it sit for about 20 minutes or more, when I go to start it it will crank over for about 6-8 seconds, misfire once, crank for another 2-4 seconds then start. If it is less then the 20 mins or so then it starts right away.

I did one test this weekend and found that if I shut the car off, unplug all the injectors, and try to start the car again that it will actually momentarily start meaning that there is fuel left in the cylinders. Then if I plug all the injectors back in it starts perfectly. Seems to me that the cylinders are flooding when the car is shutting off.

Is it possible that the injectors are leaking when the car is off but there is still fuel pressure in the line? All of this started about the time I relocated my battery to the trunk as well. Is it possible that there is some current going to the injectors after the ignition is cut, allowing the injectors to stay open?

Thank guys.

 

[TALONTRAX]

That`s possible. To check this, connect a fuel pressure guage to the pressure line & note the pressure at engine shutoff. Then, after your 20 minute mark, check the pressure again - if it dropped more than 5 or so psi, you probably have 1 or more seeping injector(s) . . .

 

[91dsmgsx]

you can also check the voltage at the injectors after you shut the car off, if there is voltage check everything that you changed when you relocated the battery.

 

[DKneble]

Update:

Fuel pressure is at the usual 43.5 psi when idling with the vac line disconnected. As soon as the car is shut off the pressure drops to almost 0 (about 5-8 psi). Note I am running a -8AN feed and -6AN return with an aeromotive FPR and 255 in-tank in series with a Bosch 044 in-line.

I checked voltage and there is none going to any of the injectors when the car is off.

Ideas?

 

[DKneble]

Capacitor failure in ECU possibly?