When the engine does not start, does it crank over and not start or does it not crank over at all?
When the engine does not start, will it fire up with starting fluid? If so, maybe you just have a fuel delivery concern??
I would rec to start by checking the fuel pressure. Fuel injected cars are very fuel pressure sensitive. Fuel pressure is very important and must be within specifications! But if the pressure is low, it does not mean the pump is bad. A plugged fuel filter, a pinched line, and low voltage at the pump can contribute to low fuel pressure. All three must be check before replacing the pump.
Thanks for the information. Have you actually checked power to the fuel pump when this is happening? If not, this would be the next step.
THanks for the info!
It sounds like you are definitely on to something! Lets check for voltage at that fuse with a voltmeter to see how many volts are are actually getting.
Let me know!
I get 12 volts at front blade #30 whether cranking or not. Then I get 12 volts at left blade # XXXXX but only when cranking did this with relay unplugged and probe in blade connection on fuse box.
SO I take it the relay is not getting activated when cranking the engine over? IS the computer supplying a ground to trigger activate the relay?
Are there any anti theft lights or security lights on or flashing on the dash with the key on?
Thanks for the update!
Have a great night!