New engine won't start, part 2

I'm not very good at this but do think it is possible that maybe one of the fuel lines is in the wrong place? If you don't have pressure on the shrader valve on the rail then you have a prob. in your fuel system, because you should have pressure when the key is on

If you can get it to crank again check for spark. I had an identical problem with my car. Car would crank, mine had fp thought but in any case wouldn't start after I did the motor and wiring in the car. I tested everything and everything tested was fine. I ended up giving up on it after weeks of messing with it. I had it towed to a garage and he somehow got it to run. He tested everything like I did and said everything was fine. In any case the car started for him and he had no idea what the problem was or how he fixed it. Go figure. I know how it feels.

There is always pressure when the pump is priming. So the problem would seem to be from the pressure gauge back. Are any lines kinked? Is the pump confirmed good? GL

your static voltage is low - can you charge the battery up?

if you are sure the pump electronics are working, i would troubleshoot the lack of pressure - kink (as Blk said), bad pump, bad FPR, etc. if you can carefully do it, i might safely crimp the return line and see if pressure goes up (or you get pressure).

good luck.

I meant the lines in the back of the car around the fuel filter and the lines going to the top of the pump. I don't think you can switch the lines on the fuel rail. But could the fuel pressure regulator be a problem here also? Is it aftermarket or anything. But I would check the rubber hoses in the back... make sure the hoses are going to were they should. Cuz if you switch them... wouldn't the fuel just return to the tank? I don't know just check it out

crunchie12268 said:

I meant the lines in the back of the car around the fuel filter and the lines going to the top of the pump. I don't think you can switch the lines on the fuel rail. But could the fuel pressure regulator be a problem here also? Is it aftermarket or anything. But I would check the rubber hoses in the back... make sure the hoses are going to were they should. Cuz if you switch them... wouldn't the fuel just return to the tank? I don't know just check it out

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i cant remember the line situation in the back enough to remember if one could switch the lines. you would have no pressure if the lines were reversed, as far as i can tell (though i have not thought about it).

i might go back further (up the line, toward the pump) to see if i can find pressure. if there is none back by the filter, i would be worried.

with the FPR, check for fuel in the vacuum line that goes to it. then the crimp on the return line test works for helping to decide which went south (do note that people use the test on a previousl-functional set up. since yours was down and there are other variables (lines themselves, etc), it might invalidate the test.

good luck.

StabNsteer said:

I spent today trying to get this car to run with no luck. As I said in my last post, i have a '91 LX that I put a new DSS 306 in with Edelbrock heads, Crane 2031 cam, Cobra intake. Almost everthing is new. Last week the engine would turn over, had oil pressure but no fuel pressure at the gauge on the fuel rail.
Today I put in a new fuel filter but theres still no pressure. the cut-off switch is not tripped. the new MSD distributor seems to be in phase and on the right cylinder. The pump comes on when the key is switched on and the relay clicks. I sprayed some starting fluid into the TB but still no start.
With the key on, I have 11.6volts at the coil. I pulled a pug off an injector and theres 11.7volts there.
I think I cooked the starter because now the engine won't even turn over anymore, so I could'nt check for spark at the coil and plugs.
I'm starting to think about taking the car to a shop to get it running but I don't know of any in the San Fran. Bay Area that I trust for this. I'd really like to get it done myself, I've gone this far. Any ideas?

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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. See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html for a description of the test connector. 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. 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 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.
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.

See http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif for a diagram of the wiring for 90-93 cars.

Now that you have the theory of how it works, it’s time to go digging.

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.

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 less than 1 volt.

StabNsteer said:

I think the starter is cooked because it won't turn over anymore.

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Take a screwdriver and jump the terminals on the starter relay...the thing just right of the battery that's attached to the firewall. Watch for sparks. If it cranks, your starter is fine. If not, climb under the car and hit the starter a few times w/ a rubber hammer or something and try again. As a last resort, you can pull the starter and have it tested at autozone, but be warned that it could do perfectly fine on their test, but fail under load. Good Luck.

BTW, you do have gas in the tank right? No gas would produce no pressure

Did you remember the ground strap from the back of the head to the firewall?

you probably just ran the battery down too low to turn the starter motor. you are recharging it - good job.

there is someone else who just had the same issue going on (no pressure being read, but pressure after all).

good luck.