Mustang Stalling and will not start

I was driving down the highway until the engine until the engine check light came on. I pulled over to see what it was and it was for “p0420”- Catalyst System Efficiency Below Threshold, I knew I had a cat delete so I thats probably what it was. I continued to drive until the car rpm started to drop and I was pressing the gas and it wouldn’t do anything. I rolled it over to the emergency lane and as soon as it stopped; it died completely. I started it back up but it died almost instantly and on the 3rd/4th attempt it wouldn’t even start.I ran the scanner and the code was “P0148”- Fuel Delivery Error. I towed the car to the mechanic and he said that the fuel pressure is good however no-one of the coil packs are getting any power= no spark.



MSD coil packs

Cold air intake

blow of valve

So what year is this imaginary Mustang?


2015 Mustang Ecoboost

So this is the same Mustang you’ve had 2 posts previously for stalling and no start?

If you really have removed your catalytic convertor you are in violation of federal law and I would hope no shop will fix your problem until a catalytic converter is reinstalled.

yup, i installed new fuel pumps

What does that have anything to do with stalling?

For the later model Mustangs, they recommend replacing the sensor when this error occurs. That often clears this error code. You might have the mechanic test fuel pressure with the engine running (though this can be tricky to do). As I recall, that car has a sensor to control fuel pressure. It could also be the fuel shutoff. Most FI engines kill the fuel when the engine is turned off. The car will usually restart because a different sequence is used at that time. With the coils receiving no power, it sort of points to that being a possibility since fuel and spark seem to be shut down. (It’s a relay that comes on with the key is in the “run” position.)

On a different note… you might have problems trusting the computer since you’ve overridden the factory system. As mentioned, putting in a Cat Delete is a really dumb thing to do, but not just because (in rare cases) it can cost you $10K. Your car needs the inputs from the O2 sensors to determine the proper fuel mix. With the O2 sensors in place, the computer thinks it’s running too rich and will lean the mix. With those gone, it’s a toss up between running too rich or too lean. Both are bad for engine life… not to mention dumping 100 times as much pollution.


Can you explain a little more on the sensors? but The mechanic has tested the fuel pressure even though the car isnt running and he told me its good. Im still confused on what could lead to no power going to the coil packs?

The mechanic told me he plugged in a light that connects from the coil and into the sparkplug which should light up if there is power. He said it failed to do so.

As I recall, there is a line running across the rear of the engine compartment, that has a sensor in it. When that goes bad it can throw the low fuel pressure fault.

As for the other, when the key is turned off, fuel injectors (or a fuel valve) cuts gas and coils are switched off, to prevent dieseling. In the modern cars I’ve seen, this is via a relay. If the relay shuts off (fails) it can kill both circuits. If the coils are still not receiving power, that would be my first suspect. Fuel pressure is up, but injectors aren’t injecting, I’d guess.

The alternative could be the car’s computer is telling the relay to shut down.

Here you go… someone using the proper terminology.

Okay well its not the PCM because I replaced it last week. I know you can do flood bypass if you press the gas all the way down when starting the car.