Help! Mustang wont start :(

[mustanglover71]

Hey jrichker

Jrich-

We tried a tire pressure gauge a few days ago out of desperation... The pin is too far inside the valve to read the pressure. Doesn't work.

To be honest, if we had bought our own fuel pressure gauge, we wouldnt have been able to afford the regulator. We then spent $7.00 on a tire pressure gauge that didn't work either. It was unfortunate that the fuel pressure gauge we borrowed didnt fit, and that the tire pressure gauge wouldnt work either. We had to make a choice based on very limited funds and what we what symptoms we had.

We called every auto shop/service station in town to see if they rented out fuel pressure gauges, none around here do.

Do you think the fuel pump continuing to run while the car is in the "ON" position means that the system is not pressurizing? The pump doesnt cut off when the key is in the ON position.

We have been told that the pump should stop when the system is pressurized and thus the car would then be able to turn over.

Considering our symptoms and diagnostics....What do you think?

Mustanglover71

 

[jrichker]

There is no pressure sensor that tells the pump relay to turn off. The computer has a built in timer that it uses to tell when to turn off the fuel pump relay.

Beware of fire hazard before you do the next step
To check the fuel pump flow, remove the schrader valve and connect a 3 foot length of hose to it. Put the end of the hose in a 2 liter soda bottle and turn the key on. Jumper the selt test connector to make the pump run continously. You should fill the soda bottle in less than 3 minutes. You could use the same method to connect a pressure gauge to the system.

 

[mustanglover71]

New regulator, still not starting

Hi guys...

Update for you... We put in a new regulator, and it still wont turn over..

Cranks fine. Now we are looking for the relay because we have someone here that can test it.

I'll keep you posted.

 

[mustanglover71]

New Relay- Still wont turn over

Ok new fuel pump relay didnt help either-
Seem to make the noises on the pump worse, clicking, knocking, coming on (humming) and then cutting out intermitently.

Check engine light is really dim, until we try to crank the car..
Could that have something to do with grounding somewhere or insufficient voltage to the computer?

The tach needle moves when we crank the engine, to about 600-700 rpms.

How do we check the ground for the computer?

Like I have said before if we buy that fuel pressure gauge, we wont have any money for these parts. Sadly we are limited on the tools we have access to. Have to work with what we havbe got. Would have been more convenient for the car to break down when we had money, of course.

Any ideas?

 

[HISSIN50]

well, Jrichker gave you an option for the lack of a FP gauge (knowing how many liters/hour your pump flows would allow you to figure out how much it should flow in one minute or some other arbitrary amount of time (like taking your pulse - do it for 15 seconds, or 30 for more accuracy). same idea.

you can get a schrader valve core removal tool for like 5 cents. that might be a route to consider, since you are very upset about the pressure gauge funds. just be careful, as Jrichker said. dont underestimate the flammability of fuel (dont forget the vapors).

good luck.

 

[mustanglover71]

probably not a code???

well, Jrichker gave you an option for the lack of a FP gauge (knowing how many liters/hour your pump flows would allow you to figure out how much it should flow in one minute or some other arbitrary amount of time (like taking your pulse - do it for 15 seconds, or 30 for more accuracy). same idea.

you can get a schrader valve core removal tool for like 5 cents. that might be a route to consider, since you are very upset about the pressure gauge funds. just be careful, as Jrichker said. dont underestimate the flammability of fuel (dont forget the vapors).

good luck.

What does the Schrader valve core removal tool do?

Just a side note- We just tried to pull codes in the KOEO position using the check engine light, but only the airbag light flashed what appeared to be a code 44, which we cant decifer....????????? Honestly we think we are not getting codes.

wha do you think?

 

[jrichker]

What does the Schrader valve core removal tool do?

Just a side note- We just tried to pull codes in the KOEO position using the check engine light, but only the airbag light flashed what appeared to be a code 44, which we cant decifer....????????? Honestly we think we are not getting codes.

wha do you think?

Schrader valve core remover - takes the schrader valve out ot the fitting. Once the valve core is removed, the fuel will flow out the fitting into whatever container you provide. You can use a cotter pin if you are careful to pick the right size and trim the legs up to the same length.


Code 44 is not relevant to you no start problem, but here is the test path:

Codes 94 & 44 - AIR system inoperative - Air Injection (smog pump)
Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source any power, 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 the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

 

[mr.p]

"We noticed that when we turned the key to the on position on the stang last night, we could hear the fuel pump come on, but it didnt cut off like it normally does after a few seconds, it just kept running... Then we heard that "Rushing fuel" sound near the rail. It just kept going until we turned the key to off."

As I have said earlier in this thread, I had the exact same problem with my 1991 Mustang and it was the computer itself. I went through jrichter's checklist and it inded was a major help. I also noticed that I had an amperage draw even with the key in the off postion. Several in the thread felt that it was rare for the computer to go out but in my case it did. I had the rushing fuel, fuel pump not shutting off, etc. I borrowed a computer from a friend and all of my problems went away and the car ran fine. For what it is worth, a remanufactured computer is ~125.00 at the local parts store.

"P"

 

[mustanglover71]

Relays....

well, we are thinking now that we may need to replace the ECC relay. Looks like it will be tough to get to, we'll have to take the computer out to reach it.

As for that schrader valve core remover idea, I am not really understanding how that would help. We already know that plenty of fuel comes out of it, we did that days ago.

It was odd to us that the new fuel pump relay actually started to make the pump sound funny (well different anyway), maybe we bought a bad relay (it was new). So we put the old fuel pump relay back in.

So now we think that this will either be a ECC relay problem, a bad computer, or the actual fuel pump. The fuel pump is the only thing out of the 3 that is less than a year old. It appears to be priming fine.

We have access to a voltmeter today, anyone have some suggestions about testing the pump or relays with it?

Please keep in mind that we dont know much about cars or wiring here. We just want to know if there is a simple way to check these components for power.

Thanks for your help.

 

[mustanglover71]

Fuel pump relay wires?????????

Ok, so we removed the fuel pump relay to check the wiring at the harness... here is what we got...

Key OFF-

Pink/black wire- 12 volts
Red wire- very little resistance
Green wire- 0
Blue wire- 0

Key ON-

Pink/black wire- 12 volts
Red wire- 12 volts
Green wire- 0
Blue wire- very little resistance

Can you guys tell what this means?
Anything else we can check with this voltmeter?
We think the green wire comes from the fusable link, is that right? If so, how do we know which harness under the hood is the fusable link, there are so many down there behind the battery. HELP!

 

[jrichker]

This path is for 87-93 cars, so the wire colors will be different for a 94 or later car. The principals are still the same. Make a trip to the auto parts store and get a Chilton Shop manual for your year car. The library can get one for you for free if you give them the ISBN number off the Chiliton manual.


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 inertia switch, 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 inertia switch (red wire) then from the inertia switch to the relay coil and then from the relay coil to the computer (green 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 (orange/ light blue wire) goes to the fuel pump relay contacts. When the contacts close because the relay energizes, the power flows through the contacts to the fuel pump (light pink/black wire). The fuel pump has a black wire that supplies the ground to complete the circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/t...witchWiring.gif

http://www.veryuseful.com/mustang/t...inks-ign-ac.gif

http://www.veryuseful.com/mustang/t...91eecPinout.gif

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

Look for 12 volts at the Orange/Lt. Blue wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring or connections. There is a mystery connector (one I haven’t found) under the dash somewhere, between the fuel pump relay and the fuse link.

Turn on the key and jumper the fuel pump test connector to ground as previously described. Look for 12 volts at the Light Pink/Black 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.
Check the Red/black 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 Red wire and Red/Black wire. Power on the Red wire and not on the Red/Black wire means the inertia switch is open.

The Tan/Lt Green wire provides a ground path for the relay power. With the test connector jumpered to ground, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the Tan/Lt Green wire. 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. 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.

If and only if you have followed the test procedure to this point and still haven’t found the problem, the computer is suspect.

 

[mustanglover71]

Jrichker or any fusable link expert....

Trying to follow the post you sent us.....What is a "fuel pump test connector"? Is that the wiring harness that the fuel pump relay plugs into? If not, please tell us where that is.

If so, that IS what we tested and got the readings we posted. Problem is...
We have volts to 2 of the 4 wires when we should have volts to 3 of the 4 wires.

We have been told that the blue wire goes from the relay harness to the fusable link. At the fusable link, there are 4 wires with a fuse on them, a yellow/black, black/orange, Black/Pink and solid yellow. NO blue wires. So how are we supposed to find the right one?

Also all of the fusable links feel stiff, and we have heard that if they are bad they should feel squishy right? Maybe our wiring is messed up somehow?

Any help appreciated....

 

[mustanglover71]

relay problem too?!?!?!?

Good grief you guys, we are at wits end here,

Put the new fuel pump relay in again, and cant hear the pump, we even tapped it, nothing.

So then we put the old fuel pump relay in and didnt hear anything, so we tapped it and pump came on! WTF!?!

Does this mean the new fuel pump relay we bought is bad? Maybe the ONLY problem is the fuel pump relay still? So now we have to take this relay back and get a new one. Still trying to figure out which wire is the fusable link too in case another new fuel pump relay doesnt do it....Will it ever end

 

[mustanglover71]

ECC relay

we finally got the ECC relay out, out the OHM meter on it, and nothing.....
original fuel pump relay gets .62, seems decent, but we still had to hit it to make it prime the pump.
new fuel pump relay only gets intermittent readings, wont prime the pump at all.
and ECC relay doesnt get any reading SO....

We will have to try a new ECC relay now and see if that does it.
Will also pick up a new fuel pump relay just in case, since the old one works, but could still be part of the problem.

I'll keep you posted....

 

[HISSIN50]

Trying to follow the post you sent us.....What is a "fuel pump test connector"? Is that the wiring harness that the fuel pump relay plugs into? If not, please tell us where that is....

i think he is referring to jumping the fuel pump with the self test connector (the connector under the hood where you plug your tester in to retrieve codes). you can ground a terminal in the connector the run the pump (connects ground to a ground pulse normally supplied from the computer, IIRC).
if i follow correctly, you could still have an intermittantly bad relay. swap the "new" one you got for a really new one.

im confused on the colors of wires you tested (the latter two wires). you list green and blue. i think there should be a tan/light green wire and an orange/lt blue wire. orange/lt blue is what supplies the pump with juice (wire comes from the starter solenoid and terminates at the FP relay connector (with a fusible link off of the solenoid).

i think tan/lt green supplies ground from the puter (it is the same wire referenced in regard to the self test connector above).

so i think if you have good constant power on the orange/lt blue to the FP connector, make sure you have pulsed ground from the puter (tan/lt green).

if so, you should be ok.

ive lost track of all the symptoms and details, so i just replied to your question in your last post(s). good luck.

Jrichker, please correct me if i messed any of this up.

 

[mr.p]

This path is for 87-93 cars, so the wire colors will be different for a 94 or later car. The principals are still the same. Make a trip to the auto parts store and get a Chilton Shop manual for your year car. The library can get one for you for free if you give them the ISBN number off the Chiliton manual.

For what it is worth, you can find an online equivalent of a shop manual on Auto Zone's web site. For instance, you can find wiring diagrams for the 1989-1993 mustang at

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp


"P"

 

[jrichker]

For what it is worth, you can find an online equivalent of a shop manual on Auto Zone's web site. For instance, you can find wiring diagrams for the 1989-1993 mustang at

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp


"P"

WOW!!! If you use the 91-93 engine controls wiring diagram, all you need to do is to follow the colors and you'll be able to find your problem.

 

[mustanglover71]

EEC relay

Wow, that autozone site is great, has a lot of information. We are going now to pick up that new EEC relay and new fuel pump relay and to see how that works. Then we will come back to the wiring diagram if that doesnt work.

Weird thing was the EEC relay available at ALL the parts stores is a 5 pin, the port had allowed for 5 pins too, but the relay we took out was only 4 pins. Don't think it will hurt anything to put a 5 pin in there since it appears there is a spot for it anyhow. Just cant figure out why the ECC relay that was in there was only 4. Weird Does anyone know what the difference this would make if it is the same number?

Anyway, We will keep you posted.

Happy Memorial Day!

 

[mustanglover71]

Giving up

It didn't work....We have decided that this is way too much for us to handle. We have to tow it to a shop...

Thanks for your help.

 

[mustanglover71]

Mustang is fixed

HI all-

Just wanted to update you, Car is back from the shop. She starts up like a dream now. It was the computer itself. They couldnt even pull codes from it. I am hoping someone else having similiar problems can read this and cut to the chase, so to speak. For good measure mechanic adjusted timing too.

The computer itself is a FORD only part, so with labor it was a spendy fix. I guess we had hoped that it would have been something simple that we could fix to save $$$. Overall we did replace about $100 worth of parts and spent money twice on towing, once to bring her home for us, and once to the shop when we gave up. So, My advice to others would be, if you have checked the inexpensive parts, don't waste any more time or money, get it to someone who can pull those codes, its worth it.

Thanks again to all of you for your help! I hope now we can fix her up to look as pretty as she sounds.

Mustanglover71