Running Extremely Rich

What year is it? if its fuel injected, Dump the codes and report back. These cars injection systems are entirely electronically controlled and dumping the codes should always be your first step to diagnose ANY drive ability/running issues.

Coboose003 said:

Okay so i tired dumping codes with the reader and it says system not responding and i tried unhooking the battery for a little bit no such luck its a 90 and injected it has 24# injectors and im now trying to get 19# cause one of my buddies said that should help ( i bought the car with 24s on it) also the fuel pump is running constantly ive tried the testing method that jrickter posted in a previous thread but dont know if i poked the right wires and if my multimeter can display megaohms

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is it the 1990 mustang? drop the code reader and grab a paper clip. i could not get a code reader to work either. the contacts on the test port are probably corroded from years sitting unprotected in the engine bay. i used the paper clip to scratch away any garbage on the contacts and it worked like a charm. to this day i still have the useless obd1 code reader unused sitting in the tool box.

Coboose003 said:

Okay so i tired dumping codes with the reader and it says system not responding and i tried unhooking the battery for a little bit no such luck its a 90 and injected it has 24# injectors and im now trying to get 19# cause one of my buddies said that should help ( i bought the car with 24s on it) also the fuel pump is running constantly ive tried the testing method that jrickter posted in a previous thread but dont know if i poked the right wires and if my multimeter can display megaohms

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If you don't have much done to the vehicle, 24lbs are way too much for the car. There is a write up on the math of how to choose your injectors based on your HP. I am too lazy too look for it, but I am sure jrichker will chime in with some helpful guide!

It sounds like you need some basic electrical help....

Automotive circuits are mostly simple stuff: a power source, a connection path, a control device, a load, and a ground.
The battery/alternator is the positive power source.
The wire and fuses are the connection path.
Control devices are switches, relays and sensors.
A load is a light, motor, solenoid or heater element.
In automotive circuits, grounds are the return path so the electrical power can flow from the load to the negative side of the power source.
Electricity flows like water:
Voltage is like pressure,
Current in amps is like volume,
Resistance is like the kink you put in a garden hose to decrease the pressure or volume.
Power is pressure multiplied by volume or voltage multiplied by current (amps)

Digest that, and you just got the first 3 days of Electricity 101.

Use some jumper wires (connection path and ground) to hook up a switch (control device), a battery (power source), a light bulb (load). Now make the light turn on and off with the switch.

That's the electrical lab for the first week of Electricity 101. People pay hundreds of dollars and sit in hard chairs in a stuffy classroom to learn what I just told you for free. So smile, you just got an expensive lesson for free

For free automotive electrical training, see Automotive Training and Resource Site . I have personally reviewed the material and it is very good. If you are new to automotive electrical troubleshooting, I highly recommend you spend a hour or so going through the material. You'll save at least that much time troubleshooting problems.


Using a Multimeter to measure resistance
Almost every meter has a different method for showing an open circuit. An open circuit is one with a break in it somewhere. That break can be a switch turned off, a fuse blown, a lamp burned out, a bad connector, a damaged circuit board or a cut or burned wire.

Without reading the instruction manual that came with your meter, I would not try to guess what your readings mean.

Step 1.) Find the instruction book that came with your Multimeter. Read it and familiarize yourself with how it works and how use it. If you lost the book or didn’t get one with it, do a Google search on the web to find the manufacturer’s web site & download a copy of the manual. Remember that while some meters auto-range to find the correct voltage range, the Ohms function ranges are usually set by the selector switch. Most of the resistance testing done in automotive troubleshooting uses the lowest Ohms range possible.

Step 2. ) Make sure that you know what test lead plugs into which jacks on the Multimeter. There are usually several different jacks on most Multimeters, and they have different functions. Make sure that your battery(s) in the Multimeter are good: if you have any doubts, replace the battery(s).

Step 3.) Once you are sure that the Multimeter is functional and you have the leads plugged into the jacks for Ohms ( the upside down “U” symbol), do some simple measurements to make sure that you know how to use it correctly. Set the switch to the lowest range and touch the leads together: you should not see “nothing” but you should see 0.3-1.0 ohms. Measure a 60 watt light bulb: cold it will measure about 17.5 Ohms. It you measure it while it is hot, the reading will be greater.

Step 4.) Make several test measurements using the ohms function and the DC volts function. Remember all resistance measurements must be done with the power off the circuit. This avoids false readings and possible damage to the ohmmeter.. Repeat steps 3 & 4 until you are sure that you can do it without making any mistakes.


Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.





If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10




Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30-$36.

Coboose003 said:

Okay so i tired dumping codes with the reader and it says system not responding and i tried unhooking the battery for a little bit no such luck its a 90 and injected it has 24# injectors and im now trying to get 19# cause one of my buddies said that should help ( i bought the car with 24s on it) also the fuel pump is running constantly ive tried the testing method that jrickter posted in a previous thread but dont know if i poked the right wires and if my multimeter can display megaohms

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The fuel pump running constantly will cause you to not get codes. KOEO test turns the fuel pump on and then off, if the computer can't do this, you can't get codes. For what it's worth, I just recently picked up a '92 F250 with similar symptoms. Ran extremely rich when it would start, constant fuel pump running and couldn't get codes. I had to put a used computer in it and it fixed it. I also have a buddy whose F150 would continuously have the fuel pump running and it wouldn't start when this happened. He ended up going to Autozone and buying a reman computer and it's been months now that he hasn't had this issue. I'm not saying for sure you have a computer issue (The cars are less prone to it than trucks due to location) but I'm just throwing out suggestions.

Also another thing is make sure your MAF is calibrated to your injectors. If you have a stock MAF and bigger injectors, that'll cause it to run rich. If you actually have a 24 lb calibrated MAF and you step down to 19's, you're going to run lean.

Coboose003 said:

ok so i changed the computer it took quite a while for me to find an a9p none of the autopart stores had one but as soon as i plugged it in and turned the key the car started right up and it ran amazingly i had the injectors changed before the computer got swapped out and the car runs compeltely fine without the scent of fuel and the fuel pump doesnt run constantly so i guess this is another instance to add to the list 88lx

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It's good to hear you got it going!