Hey all, hoping someone can help me as i'm almost bald from tearing my hair out. I was driving my 05' Mustang last night (August 7th, 2015) and the car just shut off completely in traffic. Lights, battery, etc all working just fine. It would turn over without any battery power loss, but it would not start. It would not even try to catch. The fuel pump was not priming. I had it towed to the shop and the next morning they checked both of the fuel pumps and fuses and all were good. The car is getting spark. The battery is good, the alternator is good/charging, The inertia switch has not been triggered either. The fuel pump was actually replaced about three years ago and is checking out ok.

Now, at the shop after all of this had been done, the car actually started up without fail, but again I did not hear the fuel pump priming when i turned the key on (maybe it did and my hearing was bad at the moment??) They ran a scan of the electrical and computer, codes, etc and nothing came up. The engine light is not on at all. I drove the car about 15 miles and the EXACT same problem above happened again! Could it be the fuel pump driver module? Could it go bad without the engine light coming on? I need some ideas seriously.

 

Clean all the ground connections you can find. Especially the one for the PCM, which is on the radiator support.

 

crank position sensor. I know with Mercedes, the fuel pump doesn't run without a crank signal. crank sensors go out often, in the MB world. Easy to test. Hook up ohm meter to sensor, (need to remove from car) and watch ohm reading when you put a heat gun to sensor. should't take but a few seconds for reading to go to infinity. Needles to say don't cook the crap out of the sensor, or start melting it. 5-6 inches away will do the trick. If you don't have a heat gun, a hair dryer on high will work

It doesn't always leave a code either