2001 Mustang Gt Will Not Start

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by Dr_Mark, May 21, 2014.


  1. Dr_Mark

    Dr_Mark New Member

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    I have a 2001 Mustang GT. Here is a brief history in case any of this sparks a thought with somebody.

    The car ran great most of the time ( 2 yrs ago). The car would sometimes start hard and run very poorly (lots of misfires and would not hold an idle) if it had rained or was raining. High humidity (in Florida) seemed to be a factor as opposed to something actually getting wet. After the car warmed up, the car would immediately run fine. I am assuming the computer switched to closed loop and the O2 sensor kicked in. Then I moved to Texas (no humidity) and drove the car for a year without a problem. About a year ago, the intake manifold cracked at the thermostat housing but didn't have time to replace it. So the car sat for about a year.

    Fast forward to 2 weeks ago. I replaced the intake manifold and charged the battery. The car started hard and ran very rough as it did on high humid days in Florida. But even after the car warmed up, it would not run better. I let the car sit for a couple of weeks, recharged the battery again, and purchased an OBDII device.

    Now. I put the OBDII on the car and kept the car running until the car warmed up and the closed loop condition started. After a few minutes it ran pretty good, but would not hold an idle unless I helped a bit with the gas pedal. The car eventually stalled. When I restarted the car, it ran very poorly again. It would run slightly better in the closed loop condition, but it still ran very poorly. It sounded like half of the cylinders were not firing. Eventually the car stalled at low rpms and now the car will not start. The engine turns over but will not fire. If I touch the gas pedal, the pistons spurt a bit like they are trying to fire and the rpms kick up just a touch, but that's about it.

    When the car was running in closed loop, the O2 sensors on one side were fluctuating wildly between 0.1 and 0.9 V. The other side seemed rather stable (I don't recall the voltage but I think it was mostly at 0.9V on the pre sensor and lower on the post sensor). Unfortunately I did not get any other information before the car died.

    When I try to start the car now, the first set of fuel trims (presumably short term memory?) fluctuate between 30-50% while trying to start the car and the second set of fuel trims are set at 99% (presumably long term memory?). The MAF is set at 3 g/s and goes up to 5 g/s or so when cranking the car. The fuel pump reads around 15 when cranking and drops to zero when I touch the gas pedal. The Timing Advance is at 10 degrees.

    Because the battery was dead I don't have any error codes from past days. And the current starting and stopping hasn't generated any error codes.

    I don't get why the fuel trim would be so high. Is my computer screwed up and running the car too rich to start? I am assuming at this point that either the computer is screwed up or I blew something that is preventing a spark or the injectors from working properly.

    Any thoughts on where to go from here?
     
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  2. Three50won

    Three50won Member

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    First,make sure the pump is activating when you turn the key to the On position. You should hear it kick over. If no noise, then check the fuel pump disable switch in the trunk and/or the fuel pump fuse under the hood. If they are both fine and still no kick over then your fuel pump is dead. If you do hear it, then go to your schrader valve and check to see if fuel is actually getting to the fuel rail. Pop off the valve cover and carefully press on the valve to see if any fuel squirts out. If so then your problem is with the injectors or there is a timing/spark issue.

    If no fuel is present through the valve then something is preventing fuel from getting from the pump to the rails. Either a clogged line, clogged fuel filter, or the pump itself is clogged. You can isolate the problem by using a fuel line disconnect tool to disconnect the fuel line from the fuel filter. Place a think rag on the tip of the fuel line and turn the key to the On position. Go check the rag for fuel. If fuel is present then the problem lies with your fuel filter or somewhere between the filter and the fuel rails. If no fuel is on the rag then your problem is in the tank. Another way to do this check is to have someone turn the key to the On position while you hold the rag in front of the fuel line and see if any gas comes out.

    If you are getting fuel through the line and up to the schrader valve then you need to check your fuel pressure. Maybe you're not getting enough pressure to start and run the car. Maybe check your fuel pressure sensors. Or pop the fuel line off and check the injectors...maybe they're toast. For what its worth it might be a good idea to just get a set of stock injectors. You can get them very cheap. If you don't need them then either keep them as spares or re-sell them. I personally keep a set of 19s and 24s just in case I should ever need them. If you have adequate fuel pressure, no clogs in the rails, and all the injectors are functioning properly, then your problem may be with the ECU or it may be a different problem altogether...maybe spark. I hope I helped you.
     
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  3. Kilgore Trout

    Kilgore Trout Fried or Broiled ?

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    I agree with the above fuel related troubleshooting, however check the plug wells real quick for liquid. That could be shorting out the spark. Fluid and debris tend to accumulate in those plug wells and it kinda sounds like that could be part of your issue. Do not spot check, actually examine each and every plug well with a flashlight to really see what is down there.
     
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  4. Dr_Mark

    Dr_Mark New Member

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    OBDII says I have fuel pressure, but I'll pop off the line just before the rails and check it like you suggested. I just had the rails off to do the intake so they shouldn't be clogged. I can pop them off too and check to make sure they have fuel flowing, easy enough.

    I'll check the buildup in the plugs wells. I just did the intake so they should be clean unless there was a problem with my installation. I don't have a problem double checking my work though.

    Is there an easy way to check for spark? I sure do miss the carb and distributor days, lol.
     
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  5. Kilgore Trout

    Kilgore Trout Fried or Broiled ?

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    You can have the coils bench tested at the stealership. That is the best way, are there codes indicating a miss? The miss code indicates which cylinder is missing also...
     
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  6. Three50won

    Three50won Member

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    One thing I missed...you changed your intake manifold. Did you run a new intake manifold gasket and torque the bolts down in the proper sequence to the proper torque specs? Are you sure you ran the proper connectors to the proper injectors and COPs? Are you sure you ran all the vacuum lines properly? And did you check for vacuum leaks? Are the injectors seated properly? Is the rail seated on the injectors properly? Because if your car ran fine 2 years ago until the intake manifold issue, and then you changed the intake manifold, and now you're having issues, then I'm thinking the problem is somewhere with the intake manifold.

    And one last thing, not to scare you, but did you make sure that nothing was inside that intake manifold before you installed it? No bolts or washers or anything? And did you make sure that every single last washer and bolt that came off the old manifold was accounted for. Because your problem might not be fuel after all. If you had a washer slip out and get into the intake track, then I bet it got into the cylinder head and slipped into the valve and is keeping the valve open. If your car sounds like its not running on all cylinders then I think that may be your problem.
     
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  7. Dr_Mark

    Dr_Mark New Member

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    The battery was dead so any old codes were erased. No new codes have been generated.

    I've double and triple check the manifold work. Torqued everything down to spec with new seal that came with manifold. I labelled the connectors to injectors and all vacuum lines so I wouldn't mix them up. Injectors and rail are seated. I checked them again today. I was neat with all bolts and such. Nothing missing or extra at end of work.

    It seems to me that something was dieing slowly, but I can't imagine what that would be. It ran poorly with humid conditions (in the past) until O2 kicked in. It ran fine in TX for a year but no humidity where I am. Yesterday, it ran like it did in FL with high humidity until it completely died. It seems that something finally died but I can't put my finger on what it could be to cause this problem. The basics are check spark and fuel. Fuel is easy to check at the rails. I'll pull the plugs and check for spark on each plug. I'll do both of those in the morning. Perhaps that will reveal more clues.

    I'll post my findings tomorrow. Until then I'll keep checking back for more ideas here. Thanks!
     
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  8. Dr_Mark

    Dr_Mark New Member

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    I checked for fuel just before the rails, nothing. I'm going to back track and find the issue. Thanks guys! I'll let you know what I find.

    Thanks!
     
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  9. Dr_Mark

    Dr_Mark New Member

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    I checked the fuel line back to the fuel tank, dry.

    I checked voltage to the fuel pump from the shut off switch in the trunk. The shut off switch is not getting voltage under any conditions (key on; or key on and cranking).

    I checked the 2o Amp fuse under the hood for the fuel pump and the fuse is good. I also checked voltage to the fuse and the fuse has voltage (12V).

    So somewhere between the fuse and the fuel pump cut off in the truck, I am loosing my voltage to the fuel pump. I know there is a relay somewhere but am unable to identify where it is or how to test it.

    Any thoughts on how to track down my problem?
     
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  10. Three50won

    Three50won Member

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    Hmm, is there a way you can check the actual wires that go to the shut off switch? Because if the wires are hot then you know that something is wrong with the shut off switch. Just kinda spit ballin here. Also, there is an electrical switch that goes somewhere in the trunk before the shut off switch. I forget the name of it. I actually have one...I'll try to look up the name. If that goes bad then you lose voltage to the pump. Its in my trunk. I'll grab it and post a pic to show you.
     
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  11. Dr_Mark

    Dr_Mark New Member

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    I checked the voltage coming into the cutoff switch in the trunk. The input line to the switch had no voltage even when cranking the car.
     
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  12. Dr_Mark

    Dr_Mark New Member

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    Actually, when the key was turned on (not cranking), the voltage did a quick spike (about 0.3 volts on a digital meter) and then dropped (and stayed) to zero immediately.
     
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  13. Dr_Mark

    Dr_Mark New Member

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    I'm studying the wiring diagram today. It looks like the hot for the inertia fuel shut-off switch in the trunk comes directly from the constant control relay module (CCRM) which also feeds the same hot line to the PCM.

    Any idea how to test if the CCRM is bad?
     
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  14. Dr_Mark

    Dr_Mark New Member

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    Are you talking about the Fuel Pump Driver Module (FPDM). Is that between the inertial shut off and the fuel pump or is the inertial shut off between the FPDM and the fuel pump?
     
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  15. Three50won

    Three50won Member

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    Yes, I believe the FPDM is what I was talking about. I bought one a few months ago but I couldn't find out where it actually goes. I didn't see anything that looked like it in my trunk. Besides, that wasn't the problem I had with my car anyway, lol!
     
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  16. Dr_Mark

    Dr_Mark New Member

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    LOL, ok. I found the schematics for the CCRM. Tomorrow I'm going to check all the fuses to make sure the ECU and CCRM are both getting power. Then I'll check the inputs and outputs to the CCRM to make sure they are good. Hopefully that will identify the problem. At least I'm getting closer.

    What I'm going with now is that the fuel pump cutoff isn't getting the voltage from the CCRM. So either the CCRM isn't getting a relay signal from the ECU or the fuel pump relay in the CCRM isn't working.

    If anybody else has any thoughts I'm all ears.
     
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  17. Dr_Mark

    Dr_Mark New Member

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    It's my fuel pump. The wiring diagram in Hayne's is wrong, big surprise. The inertial fuel cutoff does not run directly to the fuel pump (as Hayne's indicates). As best as I can determine, the inertial fuel cutoff acts as a sensor input into the fuel pump driver module (FPDM) which controls voltage to the fuel pump. The FPDM relays voltage from the CCRM to the fuel pump. I found the pinout for the input voltage to the FPDM from the CCRM and it was 12V. I checked the output of the FPDM at the fuel pump connector and it was 12V. So I connected 12V directly to the fuel pump connector and I heard nothing. From what I have been able to find to read, I should hear the fuel pump if I apply voltage directly to the fuel pump at the connector behind the fuel tank (brown/pink (hot) and red/black (ground). I heard nothing.

    I did a little reading and the hardest part of replacing a fuel pump seems to be dropping the half full tank I have. Other than that the job seems pretty straight forward.

    Thanks for you help guys. The tip on the FPDM was a life saver!

    I wont be able to work on the car again until next weekend. I'll let you know how it turns out.

    Mark
     
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  18. Dr_Mark

    Dr_Mark New Member

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    Sorry, wrote that wrong. It's been a long weekend. The CCRM relays voltage to the inertial fuel shutoff. The inertial fuel shutoff relays voltage to the FPDM. The FPDM relays voltage to the fuel pump.
     
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