Code 96

[prgt347]

Still having issues with car not starting. Have posted twice before on related issues (Coil Bad? & Erratic TPS) that have been fixed but now onto code 96.

After I replaced the coil last week I noticed far more spark coming from my coil wire than before but car still wouldn't start. Playing with it today and pressed the fuel pressure valve and got mostly air. Primed it a few times by turning the key on & off but still got air. Gas tank is definitely low so I put a gallon in the tank and it started right up! I ran around the block at various speeds and it ran great. Got back home, turned it off and now it will crank but not start again. Ran codes and got 15, 21 / 96. (yes, I added more gas to make sure that wasn't the problem!)

15 is likely due to my battery dying a month or so ago and even though I have a new one in the car it hasn't started in over 3 months with the exception of today. I could be wrong but I think after driving for a couple of days this should clear. If I remove the SCT chip the code will go away.

21 could just be due to the fact that it's cold out right now. Testing in 50 degrees or so...

Code 96 - First off, I am now getting fuel at the Schrader valve - no more air. With key in On position I can hear the fuel pump start up. Lasts about 2 seconds (as it always has) then cuts off. I hooked up a fuel pressure gauge and when the key is turned on pressue jumps immediately to 38-39 psi. As soon as the pump turns back off pressure drops to 29 psi then continues to fall slowly to under 20 psi. I jumpered the fuel pump and ground in the test connector and the pump comes on and stays on. Fuel pressue stays at 38-39 psi while pump is running. Green/yellow wire has full volts at relay; Pink/black wire has full volts at relay. I even tried cranking the car with the fuel pump jumpered to stay on but it still didn't start.

One more thing. While the car has been sitting for over 3 months there hasn't been much gas in the tank. After driving it and trying to get it to start again as I primed the pump (key on & off) I could hear somewhat of a grinding noise coming from the pump. But as it did it a few more times it went away and sounded smooth again.

I have a spare fuel pump but really don't want to have to drop the tank and replace it just to see if this is the problem. I've read through the various checklists put out by jrichker, who I thank tremendously for getting this far, but before I run back through them all again wanted to see if anyone had suggestions based on some of the testing I have done.

 

[prgt347]

I need to mention I am also getting a code 95. Both point to fuel pump circuit. Will keep testing but if anyone has suggestions in the meantime please let me know.

 

[jrichker]

No info about your car's model year. Makes it hard to troubleshoot when we don't know what you have.

Therefore, no clue as to which wiring diagram you need. The wiring changed several times between 79 & 95.

That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.

 

[prgt347]

Right. You had mentioned that before so I went into "my garage" and updated everything I've done to it. Are members able to see that? Hope so in case you need a list of everything. But I didn't catch the sig...my bad.

Update on the car. Been running through your "cranks won't start checklist" and everything seems to be passing but still no start. Went out Monday morning and it turned over and started. I turned it off and tried it again and it started right up again. I ran around the block and noticed under load the car hesitates but cruises just fine. I came back and ran codes and got the 15 and 21 again but 11 on the 2nd set (codes 95 & 96 cleared out). Engine running code was 11 also.

I was getting fuel pump related codes before so wondering if the hesitation is fuel-related. I haven't tried it since but will in the next couple of days. Will post again after testing...

 

[jrichker]

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error. Warm the engine up until you get good hot air from the heater and then dump the codes again.

The ECT sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the RH front of the engine in the water feed tubes for the heater.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector from the rear. A pair of safety pins may be helpful in doing this. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

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 Mustang FAQ - Wiring & Engine Info

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

 

[KobraLX]

If you look down below this post, you'll see I had that code also along with 33, and 87.

Replaced the EGR and fuel pump relay.......and I am currently at work with it. Started and shut it off several times and it appears to be good. Plus the intermittent check engine light is off right now that was occurring at 3000rpm.
Admittedly it would appear the EGR was causing most of my problems though as I did them on at a time........

 

[prgt347]

The code 21 was the key I was overlooking...my ECT sensor went out which apparently causes the car to not restart. Learned this by holding my foot on the gas pedal while trying to crank it up. It was rough, but it would start back up every time and was the only way it would start back up again. Then the hesitation issue was because with the dead ECT the engine was running rich and flooding it out under load. Replaced the $20 part and it's running good again...Now onto the other repairs, maintenance, cleaning......