2001 mustang gt, crank no start

Hello everyone. My 2001 mustang gt will crank but not start. My theft light is flashing once per second without the key in the ignition I think it was flashing slower before the trouble not sure. However the light will go out while cranking. After 3 seconds it does prove the key. If I use a non programmed key, the light will flash very very fast while cranking. So I assume it is seeing the programmed key. The fuse for the fuel pump is good with 12 volts on each side. There is 12 volts into and oput of the inertia switch. I can hear a relay click under the passenger fender well when turning on the key. I want to check the fuel pump driver module to see if it is being pulsed. I didn't check for spark yet or if the injectors are firing.I don't want to throw a $600.00 fuel pump in without being sure it is bad. Any suggestions to point me in the right direction would be appreciated. Thank you. Frank Aiello

Give it some fuel in the form of a shot of something flammable like brake cleaner/ easy start / propane in the intake whilst cranking. If it runs on that then you have a fuel problem, if not it's spark, compression or timing (more or less!)

Hello Wightscope, Did as you said I gave it a shot of starting fluid, damn thing started right up and stayed running. Turned it on and off a few times ran fine if I let it sit a few days (like I have in the past) it will act up again. This really mystifies me once while running, the fuel pressure dropped to zero without stalling, I blipped the gas and it shot up to 40 PSI. then back to 30 PSI and stayed there. Doesn't throw any codes. Last time when I changed the fuel filter (I thought maybe it was clogged) when I cycled the key the pressure went to 10 PSI, cycled the key again and it went to 20 PSI but no higher no matter how many times I cycled the key. It started with 20 PSI then after running went up to 30 PSI.I still don't know if I am looking at a bad fuel pump or fuel pump control module. Any ideas? Thank you for your input, I really appretiate the help. Frank Aiello

Have you looked at your fuel trims to see where they are at? Is the fuel pressure gauge definitely good too?

Thank you for the info, when I get time I will try another fuel gauge and hook up my scan tool to check fuel trim. This morning car wouldn't start again. I found if I cycle the key on and off a few times it will start. Am planning on cleaning the ignition switch, not much faith in that though, am thinking by cycling the key it's bumping the fuel pump. Not sure though.

Ok so that narrows it down to fuel at least!

It could be the pump that has dead spots and it will not re-start when it stops on one. An easy test for that (I'm assuming you don't have a scope) - next time it is dead give the fuel tank a good couple of thumps, if it starts right up then the vibration just moved the pump enough to get to a live spot and it will start running. - The easy-start worked for the same reason, the vibration of engine startup kicked the pump into life.

It could also be that one of the relays or wires between the battery +ve and the pump or -ve and the pump earth can not pass enough current to run the pump at full pressure. A voltage drop test would be the way to go on that, I can advise if you are uncertain, or I am sure SD has a video on it.

If it was the key I would expect you to have a dead dash when on, not just a dead pump.

If it is the pump it may well be possible to dismantle and clean and/or replace brushes.

Makes perfect sence what you said about dead spots on the pump as this has been an intermittent problem. I do have a scope but it is ac powered, I am afraid to use it due to the different grounds between my house and the vehicle. If it is the pump driver module I would be looking at, I don't have the pin-out for it. Can I assume that since it has spark and the injectors are firing that the PATS is not causing trouble? From what I read PATS disables spark and fuel pump. I will check SD videos for voltage drop tests. Thank you for your input, I am really appreciative.

Yes, I would say as it runs and keeps running you are good as regards PATS.

I think the thump test is going to be pretty conclusive - if it works.

If not, you could substitute a load such as a headlight bulb for the pump, then watch it when you turn on the ignition - Ideally you would want a wiring diagram (someone on here might have one), but the power wires at the pump should be obvious as they will be thicker than the sensor wires. However whilst that would tell you the powers and grounds to the module are good, teh wires in between can carry current and the pump driver module is good, it would not tell you if the pressure sensor was bad or if the module was not responding properly to the sensor.

The beauty of a scope with an amp clamp is that you can clamp it on the power supply for the pump and see the dead spots from the current drop outs to give a near as 100% diagnosis as possible.

Once again, thank you for your input. I tried the thump test but it didn't work. I will borrow a DC powered scope, and possibly an amp clamp. ( as soon as I find a wiring diagram for the fuel pump driver module ) and send a photo of the display. Will the waveform show the dead spots in the fuel pump? Thank you again. Frank

Yes.
Here is Eric O on the subject
(trying and failing not to look like a Picoscope advert!)

This is our host SD on the same returnless system I assume you have (not many Mustang GT's in the UK!)

Execellent videos, Can I assume I can hook my scope up to the fuel pump fuse, and get the pump waveform? If not would back probing the fuel pump control module like in the video produce any usable waveforms. Thank you.