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Daniel, Ford Technician
Category: Ford
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Experience:  Ford Technician
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Hi, I have a 95 mustang GT 5.0 car wont start, just cranks

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Hi, I have a 95 mustang GT 5.0 car won't start, just cranks till battery dies or I give up,
sometimes dead battery is jump started and it starts, works fine for a few days weeks or months then won't start again. thought at first maybe fuel pump but when key is turned on I here the fuel pump run 2 sec thought pump may be ok so instead replaced fuel filter, car worked great few months thought cool, but again won't start, this time checked coil and plug wires to see if any spark. (NO SPARK) replaced power pack. car starts now I think I have it licked, some time goes by and same thing. so I replace the ignition module. car works great again for a time then again the problem starts.
So now I am sitting in parking lot after work car won't start O degrees out side great here we go again, this time I turn key and here pump run 2 seconds then crank engine
not starting, this time I left key to the on position by accident, I'm calling for a ride home, then I here a sound from the fuel pump like the two second sound that I here at first crank, I turn key to crank engine and it starts, so every time this problem starts to happen this my new procedure. (sit wait for sound of pump w/key to on position) now that I have this info I talk to a mechanic and he says I should try to replace the pump relay and the main ECU relay. He thinks one of the relays are hanging up. what are your thoughts, fustrated in Chicago

I say its worth a try. But you could have a bad ground also. A fuel pressure test wil also tell you if your pump is getting weak or have a bad regulator.



Provides pressurized fuel to the fuel injectors.

The pump is a turbine type hydraulic unit directly coupled to a permanent magnet motor. Fuel is used as a lubricant and coolant for the motor.
A check valve is incorporated in the fuel outlet and a pressure limiter valve is located on the pressure side of the fuel pump housing with a return passage to the fuel inlet side.

When the rotor disc rotates, the rollers are pressed outwards by centrifugal force and act as a circulating seal. A pumping action is created by the circulating rollers which draw in fuel at the inlet port and force the fuel through the outlet port into the fuel system.
When the pump is shut off, the check valve in the fuel outlet will close, therefore prohibiting the fuel from returning to the fuel tank via the fuel pump. The check valve will therefore maintain a pressure in the fuel lines called the "rest pressure".
The maximum fuel pump pressure (not fuel system pressure) is dependent on the calibration of the pressure limiter. If the fuel pump pressure exceeds a preset limit (for example a clogged fuel filter), the pressure limiter will open a by-pass to the fuel inlet side of the pump.



Key On Engine Off 35 - 45 psi
Key On Engine Running 30 - 40 psi

Customer: replied 7 years ago.
sounds good, but I still won't get any spark to the plugs or from the pack, i can't see that the fuel pump will control the spark from coil pack or the spark to plugs. There has to be something that will control both the spark and the fuel, that is why I am thinking the relays. or a computer problem. ti seems the most logic way to go.

Ok I must have mis read you. You dont have spark at first right? then when the pump sounds you can start it, is this correct?


If this is correct then your pump relay could be the issue. It works with your pcm that could cuase the no spark condition in your mustang. I have included some more discription for you.




The Constant Control Relay Module (CCRM) interfaces with the Powertrain Control Module (PCM) to provide control of the cooling fan and A/C clutch. The module includes the PCM power relay to provide power to the PCM.
These relays are contained in one housing, resulting in longer service life and reduced wiring requirements for operation.

The CCRM has one 24-pin connector. Relays contained in the housing are independent of one another.

The relays contained within the CCRM are interdependent and work with each other. The following describes the different relay functions within the CCRM:

EEC Power Relay
For any other circuit in the CCRM to operate, this circuit must be powered up. This prevents actuators from being turned on without the EEC system having control over them.

Fuel Pump Relay
The fuel pump relay circuit controls the fuel pump. The PCM provides the ground circuit for the primary side of the relay. The secondary side supplies Battery Voltage (B+) to the fuel pump itself.

Cooling Fan Motor Relay
The cooling fan motor is controlled during vehicle operation by the constant control relay module (CCRM) (12B581) and powertrain control module (PCM) (12A650) which energizes the cooling fan motor under the following conditions:

  • When the engine temperature is higher than normal the cooling fan motor starts operating at 105°C (221°F) and stops when temperature drops to 94°C (200°F) .
  • When vehicle A/C is on and vehicle speed does not provide enough natural airflow, the cooling fan motor starts running at or below 69 km/h (43 mph) and stops at 77 km/h (48 mph) .

Low Fan Control Relay
The Low Fan Control (LFC) relay controls the electric cooling fan. The primary control circuit of the LFC relay is normally high (B+) . In this state the low speed cooling fan runs continuously. To turn the fan off, The PCM grounds this circuit, pulling it low (near zero volts). A "fail safe" is built into the LFC circuit to run the fan anytime the EEC power relay is activated, should the PCM fail open circuit.

High Fan Control Relay
The High Fan Control (HFC) relay circuit operates the high speed electric cooling fan. If the Engine Coolant Temperature (ECT) sensor relays a high temperature or overheat condition to the PCM, it activates the HFC. In order to turn the high speed cooling fan on, the PCM grounds the primary circuit of the HFC relay. The secondary circuit applies B+ to the cooling fan motor.

Wide Open Throttle A/C Control Relay
This circuit controls the A/C compressor clutch during normal operation. This circuit also disengages the A/C clutch as commanded by the PCM during Wide Open Throttle (WOT) conditions. This solid state relay has two control circuits. One is used to engage the A/C clutch upon demand from the vehicle operator and the A/C cycling pressure switch. The other control is used to disengage the clutch upon command from the PCM.

Power Ground
This circuit provides the CCRM with a ground source for operating various controls. The circuit uses one pin that goes to the battery negative terminal.


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Customer: replied 7 years ago.

right, first car won't start, then I turn ignition to on position, the pump makes the 2 sec pumping sounds that are normal when first starting I wait till the car makes a pumping sound a second time but shorter than usual, some times i wait for a few minutes sometimes i wait 5 min. or more but eventually i will here the sound of pump then i crank it over and it starts. (if i don't here the second pumping sound and crank engine I have no spark). that is why i don't think it is pump because the pump does not control that spark.

crazy i know.

Customer: replied 7 years ago.
thanks for the info about the relays. but it is not giving me an answer to my problem.