Changed fuel pump now car won't start?

You hear the pump prime right?........do you have a mini fuel pressure gauge on the fuel rail? if you don't, prime it up and press the schrader valve on there to see if any pressure built up, if you got nothing and the pump is priming I would have to say culprit is the fuel filter or something somwhere in the line.

Have you confirmed you have adequate fuel pressure at the Schrader valve?

I would recommend utilizing JRichker's Cranks but no start checklist. A quick search will reveal it.

Good luck.

Its on the fuel rail.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Revised 21-Mar-2007 to correct wire colors on fuel pump relays.
All text applies to all models unless stated otherwise.

Note: 94-95 specific changes are in red

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) Coil
C.) TFI module
D.) PIP sensor in distributor. See paragraph 5A - a noid light will tell if the pip is working by flashing when the engine is cranking.
E.) No ECC or computer power - ECC or computer relay failure
86-93 models only: ECC relay next to computer - look for 12 volts at the fuel injector red wires
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
F.) No ECC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
H.) Computer
J.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI.

See the following links for wiring diagrams...

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars
Computer/fuel pump/ignition wiring diagram, 86 model http://www.autozone.com/images/cds/gif/large/0900823d80167158.gif
Computer/fuel pump/ignition wiring diagram, 87 model http://www.autozone.com/images/cds/gif/large/0900823d8016715e.gif
Computer/fuel pump/ignition wiring diagram, 88 model http://www.autozone.com/images/cds/gif/large/0900823d80167162.gif

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars
Computer/fuel pump/ignition wiring diagram, 89-90 cars http://www.autozone.com/images/cds/gif/large/0900823d8019595f.gif
Computer/fuel pump/ignition wiring diagram, 91-93 cars
http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars

2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.

Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the Upper RH corner to ground.


If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In a pinch, you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have. If you have any doubts about having sufficient fuel flow/pressure, rent a fuel pressure test gauge from the auto parts store. That will tell you for sure if you have adequate fuel pressure.


4.) No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) 86-90 models only: Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay.
91-93 models only Blown fuse link in wiring harness. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
The fuse links for all model years 86-93 live in the wiring harness near the starter solenoid.
94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
F.) Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running. If fuel is coming out the vacuum port, the regulator has failed.

5.) Fuel pressure OK, the injectors are not firing.
A.) A noid light available from any auto parts store, is one way to test the injector wiring.
The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and it will flash if the injector is firing.
B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
D.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
E.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
F.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the ECC relay and the red wire for the 10 pin connectors.
G.) TPS voltage exceeds 3.7 volts with the throttle closed. This will shut off the injectors, since the computer uses this strategy to clear a flooded engine. Use a DVM, a pair of safety pins, and probe the black/white and green wires to measure the TPS voltage. It should be .5-.99 volts with the key on, engine not running. Note that if the black/white wire (signal ground) has a bad connection, you will get some strange readings. Make a second measurement using the battery post as the ground to eliminate any ground problems. If the readings are different by more than 5%, you may have a high resistance condition in the black/white signal ground circuit.

6.) Spark & fuel pressure OK.
A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently).
D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
HO & 351W 1-3-7-2-6-5-4-8
Non HO 1-5-4-2-6-3-7-8
E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.

69Rcode_Mach1 said:

Hmmm I will do a search, where is this valve located, I haven't dealt much with fuel injection yet.

Click to expand...

on the fuel rail, (1 of the 2 chrome tubes going to your injectors)

pretty much right in between the alternator and the first spark plug, on the fuel rail.....might have a little plastic cap on it, unscrew it and it will look like a tire valve stem, press the center pin and fuel should come out if its pressurized, use a rag and screwdriver so it doesnt spray all over everything

did you get the lines back on the right way. Maby the first time it was running with the new pump you were running off the fuel in the lines

I agree with Roland69. Check the lines going to the fuel tank, I replaced my pump, and got the same exact problem only mine ran for a whole day, then it just died in the driveway (lucky me). After going through some checks on jrichter's list, I decided to just check the lines, and one was not off, but just barely on. Reconnected it, started right up. Just a thought from a past experience.
Good luck to you.

Fuel Pump Troubleshooting for 91-93 Mustangs

Clue – listen for the fuel pump to prime when you first turn the ignition switch on.
It should run for 5-20 seconds and shut off. To trick the fuel pump into running,
find the ECC test connector and jump the connector in the lower RH corner to
ground.



If the fuse links are OK, you will have power to the pump. Check fuel pressure –
remove the cap from the Schrader valve behind the alternator and depress the
core. Fuel should squirt out, catch it in a rag. A tire pressure gauge can also be
used if you have one - look for 37-40 PSI. Beware of fire hazard when you do this.


No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – press reset button on the inertia switch. The hatch
cars hide it under the plastic trim covering the driver's side taillight. Use the
voltmeter or test light to make sure you have power to both sides of the switch

B.) Fuel pump Relay: On 92 and later model cars it is located below the Mass Air Flow meter.

C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect
for fuel escaping while pump is running.

The electrical circuit for the fuel pump has two paths, a control path and a power
path.

The control path consists of the computer, and the fuel pump relay coil. It turns
the fuel pump relay on or off under computer control. The switched power (red
wire) from the ECC relay goes to the relay coil and then from the relay coil to the
computer (light blue\orange wire). The computer provides the ground path to
complete the circuit. This ground causes the relay coil to energize and close the
contacts for the power path. Keep in mind that you can have voltage to all the
right places, but the computer must provide a ground. If there is no ground, the
relay will not close the power contacts.

The power path picks up from a fuse link near the starter relay. Fuse links are like
fuses, except they are pieces of wire and are made right into the wiring harness.
The feed wire from the fuse link (pink/black wire) goes to the fuel pump relay
contacts. When the contacts close because the relay energizes, the power flows
through the pink/black wire to the contacts and through the dark green\yellow
wire to the inertia switch. The other side of the inertia switch with the
brown\pink wire joins the pink/black wire that connects to the fuel pump. The fuel
pump has a black wire that supplies the ground to complete the circuit.

Remember that the computer does not source any power to actuators, relays
or injectors, but provides the ground necessary to complete the circuit. That
means one side of the circuit will always be hot, and the other side will go to
ground or below 1 volt as the computer switches on that circuit.


diagram of the wiring for 91-93 cars.

Power circuits:
Power feed: Look for 12 volts at the pink/black wire (power source for fuel pump relay).
No voltage or low voltage, bad fuse link, bad wiring, or connections. Remember that on 92
or later models the fuel pump relay is located under the Mass Air meter. Watch out for the
WOT A/C control relay on these cars, as it is located in the same place and can easily be
mistaken for the fuel pump relay.

Relay: Turn on the key and jumper the ECC test connector as previously described. Look
for 12 volts at the dark green\yellow wire (relay controlled power for the fuel pump). No
voltage there means that the relay has failed, or there is a broken wire in the relay control circuit.

Inertia switch: Check the brown/pink wire, it should have 12 volts. No 12 volts there, either
the inertia switch is open or has no power to it. Check both sides of the inertia switch: there
should be power on the dark green\yellow (inertia switch input) and brown/pink wire
(inertia switch output). Power on the dark green\yellow wire and not on the brown/pink wire
means the inertia switch is open. Press on the red plunger to reset it to the closed position.
Sometimes the inertia switch will be intermittent or will not pass full power. Be sure that
there is 12 volts on both sides of the switch with the pump running and that the voltage drop
measured across the switch is less than .75 volts.

Pump wiring: Anytime the ignition switch is in the Run position and the test point is jumpered
to ground, there should be at least 12 volts present on the black/pink wire. With power off,
check the pump ground: you should see less than 1 ohm between the black wire and chassis ground.

Control circuits:

Relay: The red wire for the fuel pump relay coil gets its power feed from the ECC relay.
No 12 volts here, and the ECC relay has failed or there is bad wiring or bad connections
coming from it. The ECC relay is located on top of the computer, which is under the passenger’s
side kick panel. It is not easy to get to, you must have small hands or pull the passenger side
dash speaker out to access it.

Relay: The light blue/orange wire provides a ground path for the relay power. With the test
connector jumpered according to the previous instructions, there should be less than .75 volts.
Use a test lamp with one side connected to battery power and the other side to the light blue/orange
wire on the fuel pump relay. The test light should glow brightly. No glow and you have a broken
wire or bad connection between the test connector and the relay. To test the wiring from the
computer, remove the passenger side kick panel and disconnect the computer connector.
It has a 10 MM bolt that holds it in place. Remove the test jumper from the ECC test connector.
With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow.
No glow and the wiring between the computer and the fuel pump relay is bad.

Computer: If you got this far and everything else checked out good, the computer is suspect .
Remove the test jumper from the ECC test connector located under the hood . Remove the
plastic cover over the computer wiring, but leave the computer wiring connector plugged
into the computer. With the ignition switch in the run position, connect a test lamp to the
battery and back probe pin 22, the light blue/orange wire with it. The lamp should glow
brightly. No glow and the computer has died a sad death. If you used a voltmeter instead
of a test lamp, you should see battery voltage, whatever that may be…

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Fuel pump runs continuously: The light blue/orange wire has shorted to ground. Disconnect
the computer and use an ohmmeter to check out the resistance between the light blue/orange
wire and ground. You should see more than 10 K Ohms (10,000 ohms) or an infinite open
circuit. Be sure that the test connector isn’t jumpered to ground.

Gotta second (or third? Fourth?) the above suggestions to verify you're getting proper fuel pressure to the rails. Have at least 5 gallons in the tank, and check your PSI at prime and during cranking, and make sure it holds steady even when you switch off - if it bleeds down, something ain't kosher.

Without reading the above line-for-line, I'll go ahead and throw out the question: Have you verified you're getting fuel AND spark? You can have all the fuel pressure in the world, but if something up front ain't clickin' a spark to your plugs, you're stuck. I know it might seem totally unrelated and coincidental, being that you're working on the other end of the car, but it's entirely possible that something in the ignition system is amiss - either the switch (verify your coil's getting 12 volts with the key on), the coil (getting spark to the dizzy?), the cap/rotor (any fuzz/burn marks?), the TFI module (many parts houses test 'em for free), and/or the ignition wires (check for continuity). Worst-case scenario in that respect, maybe your pickup coil suddenly decided to give up the ghost - happened to me before, and I beat my head against a wall for a week trying to figure it out until I replaced it on a whim and woke it from its little comatose state.

Absolute worst-case scenario - you gotta drop the tank again and verify your electrical connections and fuel plumbing to the pump are good. Things happen, stuff gets knocked loose during re-installs. It happens.

Another random thought: double-check all of your electrical grounds. Maybe, just maaaaaaybe a lose or corroded ground to something like your fuel injectors has become an issue. Totally a shot in the dark, but never hurts to look, if all else fails.

69Rcode_Mach1 said:

Okay I went through and tried to jump the ECC connector like in jrichkers post. The fuel pump solenoid clicked but the pump didn't run. I have noticed that when I turn the key it is hit or miss sometimes the pump comes on for only 1 second, or not at all. Any ideas, I am so frustrated, I am not fit to deal with electronics. I really don't want to drop the gas tank again. Also at the schrader valve it was empty but then suddenly it had gas in it, so that means that I did hook the lines up properly. If i mixed up the return line with it then, it wouldn't have gas correct?

Click to expand...

I would do testing at the FP relay socket next if it were me. This will tell you which element/terminal is not hanging around as long as it should.

Good luck.

Regardless of whether you installed the lines incorrectly or even if you didn't install them at all, the pump should still run when you turn the key or trick it via the test connector. However, since it was priming before when you primed it for a hour, it has worked since installation. Maybe you burnt the pump up by priming it so much.

If your pump will not turn on when turning the key or grounding the test connector, this is what I would do:

There is a connection at the rear of the car that connects the inertia switch, fuel level sender and fuel pump. Look under the rear of the car next to the passenger side gas tank strap - it's on the side toward the middle of the car. Unplug that connection and figure out which of the 4 prongs go to the fuel pump. Use a wire to ground the ground wire and another wire to give 12v to the power wire (look the colors up on a diagram), and see if the pump will run then. If the pump runs, you know your pump seems to at least run (although it may not maintain adequate pressure). If the pump does not run (and you're attaching the correct wires), then the problem lies before the pump.

After you're sure the pump is working, you might consider removing the fuel line that goes into the fuel filter from the fuel tank. Fix the fuel line where the fuel can drain into a container and turn the pump on and see if it shoots fuel. If it does, you at least have your lines hooked up correctly and it's shooting fuel. Once you reattach the fuel line that inputs into the fuel filter, you might consider detaching the one on the output of the filter. Do the same thing and see if it shoots fuel (to make sure the filter isn't clogged...or just change the fuel filter). If all is ok there, go to the schrader valve and see if you're getting fuel there (again).

You've gotta pinpoint where this problem lies. Sooner or later, you may have to obtain a fuel pressure guage to ensure that you're, in fact, getting adequate pressure. Perhaps the pump will run, but is just not providing adequate pressure. You can buy a detachable fuel pressure gauge from autozone, etc for about $20. It doesn't stay on the car, you simply attach it to the schrader valve, check your pressure and remove the gauge when you're done.

Proper voltage is necessary for the computer and fuel pump to run. If the voltage gets too low, the fuel pump output drops off and so does the ignition output.

Use a good DMV (Digital Volt Meter) to monitor the voltage at the computer. Pins 37 & 57 are the main power feed for the computer.


Diagram courtesy of Tmoss & Stang&2birds


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif