New Fuel pump, wont start. Please Help! 99 V8 Mustang GT

Chantelb

New Member
Feb 3, 2020
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Springfield,OR
Please Help! Changed the Fuel pump, primed it, it started and ran great! When i shut it off, a couple hours later when i get in and try to start it, it cranks over but wont start. Ive checked to make sure everything is plugged in on the gas tank, checked the fuel pump reset button in the trunk, and thats pushed in, all fuses check out okay. The only thing that is out of the ordinary is that the Fuel Rail under the hood, when i pushed the valve stem in no gas came out of it. It is completely dry. What do i do now? This is so frustrating.
 
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wmburns

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Aug 14, 2009
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Just wondering. Did you remove the battery during the work? There's a ground wire that goes from the radiator core support around the battery. This is the PCM and CCRM ground. This ground is sometimes disconnected during a battery swap.

Turn the key on but do NOT crank.

Does the check engine light come on?

Does the theft light go out after a 3 second "prove out"?

Otherwise let's work through the steps in the "crank with no start" check list.

 

Chantelb

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Feb 3, 2020
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No I didnt. However the battery was dead while doing the work. The check engine light does come on and the theft light does kick off. Thank you for your response
 

wmburns

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Cycle the key on/pause/off several times. Do you HEAR the fuel pump run at each key cycle?

What about the other items in the "crank with no start" check list?
 

Shuttleman83

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Jun 30, 2019
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Check Valve can do this. Try bypassing the inertia switch, they sometimes get stuck or start losing voltage. Put a small fuse in the ends of it with wires and tape or zip tie it in. Only recommend doing this to test not for the long haul, you can get a new inertia switch on ebay cheap. Also, try new fuel pump relay or fuses, and make sure the fuel rail ground is connected under the hood.
 

wmburns

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Aug 14, 2009
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Try bypassing the inertia switch, they sometimes get stuck or start losing voltage.
IMO there are simpler ways to rule out/in a problem at the IFS.

With a volt-ohm meter (VOM), test for and confirm key on power on both sides of the IFS switch. For some models years it will be necessary to cycle the key off/on to force the fuel pump to prime. This test will work best if the motor starts and runs with the fuel pump actually running (drawing current).

Another way to test is to use the voltage drop method ACROSS the IFS switch. If the IFS switch is bad, it will show up as a measurable voltage drop across the IFS switch. In normal operation the voltage drop across a IFS switch should be sooooooo small as to almost not be measurable.

IMO one of the advantages of the voltage drop testing method is that nothing has to be disconnected. Nor do you have to have long fused jumpers.

Howto perform charging system voltage drop test

Bonus. If it does turn out to be a voltage drop problem, if understood and followed a voltage drop test can be used to narrow down WHERE the weak connection is. Even down to the inch in some cases.
 

Chantelb

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Feb 3, 2020
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Everything checks out under the hood. But now it the coolent fan light won't turn off. The radiator is full of 50/50. When it had died once again on me I had took off the radiator cap which I realize I'm not supposed to until the engine cools. But there was little to no pressure when taking the cap off and my dash doesn't say it's over heating. Thank you guys for all your help I really appreciate it
 

wmburns

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But now it the coolent fan light won't turn off
A disconnected ECT sensor can cause the coolant fan to run all the time. Another possibility is that the PCM is not alive. At the very least the CCRM is not seeing a signal from the PCM.

Have you double checked that the fuel rail pressure sensor (FRPS) is connected?

Does the cluster display the mileage at key on?

Does the check engine light go out during cranking? This is important because it means the PCM is "seeing" a signal from the CKP sensor.

You haven't answered the question about IF the fuel pump primes at each key on. Have you CONFIRMED key on power at the trunk mounted IFS switch?

1996+ Crank with no start check list

Did you go through the items in the crank with no start list? Did you see the part about confirming power in/out of Fuse F2.34, F2.2, and F2.8?

Go back to the basics. By that I mean confirming powers and grounds. The details matter here.

Do you have an ODB2 scanner? If you did it might make very short work of this problem. Knowing some key PID's might make all the difference in the world.

ForScan ODB2 scanner w ELM327 USB
 
Last edited:

Chantelb

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Feb 3, 2020
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Springfield,OR
The etc sensor is connected, the fuel rail pressure has fuel and the pcm checks out okay. The Service engine soon light is on when I turn the key before trying to start it. I can hear the fuel pump when I turn the key before starting it as well. I honked up a OBD2 to my car and it gave no codes. But when I had went 5o the I/M readiness option everything checks out okay on the list except for the HCAT and AIR
 

wmburns

SN Certified Technician
Aug 14, 2009
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The etc sensor is connected
It seems to me that most of the easy things have been checked. Things will get more complicated from here on. IMO you are working with one hand tied behind your back until you have access to an ODB2 scanner that can monitor PID's. The USB adapter is only $30.

For example. What does the PCM, Think's the value of:
  • Fuel rail pressure sensor (FRPS)
  • RPM's during cranking
  • MAF during cranking.
  • ECT
  • IAT
Yes we know some new parts have been installed. BUT...........do you KNOW for certain what values the PCM are actually receiving?

Have you CONFIRMED spark during cranking?

Does the motor make good chug chug sounds during cranking?

What about the other items in the "crank with no start" check list?
 
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