Stumped with fuel delivery problem.

[3yearplan]

The drivetrain is 2004 Mach 1, DOHC 32V, Mustang fuel tank, pump etc. Here is the dilemma: Turning the key to the on/acc position the fuel pump will come on, pressurize the system and stop, like it normally would. Turn the key to the crank position and the vehicle will start, but the fuel pump will NOT kick back on, therefore the engine only runs for a few seconds. Changed out the fuel pump, fuel pump control module, the crank trigger sensor. Double and triple checked wiring, matches up with the schematics from the Mustang, have plenty of ground wires that have also been triple checked. The computer was flashed by Ron Francis to ONLY remove the PATS and after cat O2 sensors. ANY help or information is appreciated. This has been going on for far too long. I prefer to keep this set up, but if I can't figure it out I'll be forced to get a complete new fuel system, which I don't want to do. Had it hooked up to a Ford dealer scan tool, no codes came up.

Thanks, Mike

[GoDadGo]

Mike,

Could the culprit possibly be an issue with the inertia switch?
It's that goofy looking thing up by the main wiring harness with the big Red Rubber Button with the mounting tabs on each side.

Steve

[Straversi]

I chased fuel pump wiring problems and finally got the electrical correct but still wouldn't start. Discovered the fuel pick up hose had slipped off. Fixed that and it would start but then quickly died. I assumed it was still fuel pump related but found out I had my MAF sensor in backwards. Flipped it and runs like a champ

[3yearplan]

I will certainly check both of those items. ALL ideas are appreciated.

[phileas_fogg]

Am I understanding correctly that when you go from ON to CRANK the fuel pump doesn't kick back on? If so, what happens when you go from OFF to CRANK? Does fuel pump come on and stay on?


John

[Itchief]

Do you have a pressure gauge on the fuel line so that you can verify what the fuel pressure is doing

The pressure may not have dropped to a level that would cause the pump to turn on


Rick

[Big Blocker]

So what you're saying is; Fuel pump comes on at initial start sequence, turning the key to ON, you get a single pulse to the pump (normal). Then when you crank the engine over, there is NO fuel pump function (I believe that's normal). Then when the key is returned to ON to keep the engine running, there is no fuel pump function? How am I doing so far??

To the best of my knowledge, The fuel pump needs to "see" the engine [actually] running and that function is controlled by the crank trigger. Once the engine is spinning, the pickup at the crank trigger constantly re-triggers the fuel pump to cycle again and again.
If possible, check your wiring at the crank trigger to ensure that the trigger pulses are in fact happening - sounds like they are if the engine will run until the fuel pressure drops off to a point where the engine won't continue. That being said, you may be getting the trigger pulses for ignition but not the fuel pump, causing the pump to NOT run.

IF the inertia switch was bad, you wouldn't get the initial pump run cycle, it's in series to the power lead to the pump. It's either open or closed, not intermittent.

If your fuel pump runs and gets to design pressure, it's not the fuel pump.

HTH

Doc

[Erik W. Treves]

This a classic run and stop with PATS still enabled... could be that while you asked for it to be disabled it isnt.

[3yearplan]

Gentlemen, I have no idea how to do the "quotes" thing. So I'll answer in order:

John, It will come on just for an instant and when the engine fires it will not come back on.

Rick, the initial pressure is at 45-47 psi, after it starts it will slowly drop and the engine will die.

Doc, first paragraph, yes, yes, and yes. I'll double check the wiring at the crank trigger pickup. Hmmm how could I get a crank trigger pulse for ignition, but not the pump? I've eliminated the fuel pump as the issue, put in two different ones. We have wired the fuel pump to run constantly to eliminate it. The engine runs fine that way. I know the factory pump is not designed for that type of operation, it was just a trial of two-three minutes.

Erik, how would I actually test to see if the PATS is actually disabled ?


Thanks again, this forum is invaluable for things like this. Unfortunately I don't have the "normal" engine to help out that many people.

Thanks again, Mike

[michael everson]

I have a PATS disabled car here I am working on. I believe its a 99 Computer and harness. When PATS is active, it kills the injector power too. Maybe this is specific to this year, but something to look into on yours. Sounds like you have injector power.
Mike

[3yearplan]

Thanks Mike, I'll add it to the checklist.

Thanks again, Mike.

[frankeeski]

Mike, resurrecting this thread because I'd like to see a picture of your under hood fuel lines. If your feeding the engine return-less style this won't help but if you are using a return on the factory fuel rails this may be as simple as swapping your lines. It's not uncommon to get them reversed. For reference the FPR goes on the return NOT the supply.

[Ducky2009]

Not sure if this issues is resolved, but I saw the new post dated today.

Check the MAF sensor. If it's in backwards, the engine will start but not continue to run. The fuel pump will work until the sensor doesn't see airflow after start, then turn off.

[GFX2043mtu]

I can just about guarantee it’s a pats security issue. Get a $40 vehicle mobilizer bypass like one listed below. Wire it in and life will make sense again. Gm uses a vats system like the ford the engine will fire right up and then die after a few seconds.

https://www.sonicelectronix.com/item_33818_Fortin-KEY-OVERRIDE-ALL.html?utm_source=google&utm_medium=cpc&utm_campaign=shopping-campaign-general&utm_keyword=&gclid=EAIaIQobChMIxae435TO2gIVCLnACh2HLwdYEAQYBCAB EgKxMfD_BwE

[3yearplan]

Frank, it is a returnless set up. Ducky, the MAF sensor has been checked, and actually replaced to rule it out. GFX, definitely something to look into, way cheaper than my current plan. Thanks again for the suggestions. I NEED life to make sense again.

Mike

[Ducky2009]

Did you try running a hot wire directly from the battery to the fuel pump, completely circumventing the computer, ignition, etc...? (In case the computer wasn't flashed correctly). You might want to include a toggle switch to shut off, in case of an emergency.

[3yearplan]

Ducky, that was done early on. It runs fine like that. We are in the process of coming up with a fuel system that will be standalone from the rest of the system. It will most likely have to include a return line and quite possibly a different fuel pressure regulator. Originally I didn't want to do this, just wanted it to be turn key and go, not that turning on a fuel pump is all that much trouble, but you get the point. Now I don't really care, I'll read tarot cards and do black magic if I thought it would help. PATS has been eliminated as a problem, it is turned off.

Mike

[frankeeski]

It runs fine like that. We are in the process of coming up with a fuel system that will be standalone from the rest of the system. It will most likely have to include a return line and quite possibly a different fuel pressure regulator. Originally I didn't want to do this, just wanted it to be turn key and go, not that turning on a fuel pump is all that much trouble

Mike

I ask again, get us a picture of the underhood fuel line setup. I'm working on a 4.6 right now in the shop and your description of a "returnless" system may not be the same as mine. If it works when wired directly then it's a problem with the wiring or a problem with the ECU/flash.

[Ducky2009]

Ducky, that was done early on. It runs fine like that. We are in the process of coming up with a fuel system that will be standalone from the rest of the system. It will most likely have to include a return line and quite possibly a different fuel pressure regulator. Originally I didn't want to do this, just wanted it to be turn key and go, not that turning on a fuel pump is all that much trouble, but you get the point. Now I don't really care, I'll read tarot cards and do black magic if I thought it would help. PATS has been eliminated as a problem, it is turned off.

Mike

Mike,
If it runs with a direct hot wire, it sounds like the fuel lines are good as is. You could pick a/any hot wire, when the ignition is on, feed the fuel relay and inertia switch and be good to go. Do you need to go through the computer? Not sure.... Does the computer turn the fuel pump hot wire off if the key is turned on but the car is not started (turned off after a set amount of time)? Is this what you mean as a "Stand Alone" system?

[3yearplan]

Well it ended up being a "fuel vapor pressure sensor". We didn't have it installed, basically because we didn't know it existed. Thanks for everyone's input and suggestions. It runs, shuts off, stars back up, does everything it should. Still kicking myself for going with this motor, but it's on its way to go cart stage. Not bad, only 5+ years. At least it's paid for.

Thanks again, Mike.