Just an appeal for your wisdom with a 1992 5.8L that starts then dies within about 5 seconds. Replaced (so far) the Fuel Pump (was 20psi, now 40psi), Fuel Filter, Fuel Pressure Regulator. Replaced the Ignition Coil, Distributor, Cap, Rotor, Wires and Plugs. Replaced the ECM (computer). The IAC and EGR valves, MAP and ICM sensors, the Starter Switch, Fuel and ECM relays. The only codes at KOEO are 55 (no or low volts (less than 7.5 volts) Key Power to ECM pin 5) and 56 (Vane Air Flow (VAF) or Mass Air Flow (MAF) sensor high - VAF MAF) although I have a MAP, not MAF, sensor in this year engine.
The engine starts then immediately dies.
I'm completely mystified and have no solutions. 2 other mechanics have come out and they can't figure it out.
Can you help?

 

Ford started to transition to 3 digit codes in 1991. Not to say all Ford vehicles were 3 digit in 1992, just that the possibility is getting smaller.

How did you pull those codes? And where were they displayed? (KOEO, CM or KOER). Code 55 is a Key On Engine Running (KOER) only code. That implies the engine had to be running.....

 

KOEO codes that I determined by jumping the OBD1 connector and reading the flashes on the Check Engine light. These are genuine 2-digit codes that repeat as part of the first set of codes. I do get a 512 code in the second set of codes (after the 1 flash separator) (512=disconnected the battery and lost the long term codes). The 55 and 56 codes I have registered since this 6-week effort began.

 

So now you just contradicted yourself. You will get either 2 or 3 digit codes, not both.

I am not trying to be an *** here. Just pointing out all the signs of mis-read codes.

 

Some really good EFI no-start info from my buddy Joel5.0: How to Solve an EFI No Start

I realize yours starts, but there is some good info to see if spark or fuel is dropping out.

 

The OBD1 codes are displayed in 2 sections separated by a single flash. In the first section I receive the 55 and 56 codes, which then are repeated. After the single separation flash, the only code I have received is 512, which is then repeated also. I have not mis-read these codes. I have pulled these OBD1 codes at least a dozen times during the last 6 weeks.

 

@rla2005
Excellent link and very comprehensive tool. I've suspected its either the Timing or the Injectors. Tomorrow I'll break out the electrical test equipment. Thanks....

 

You are preaching to the choir here dude. I know darn well how the codes are displayed. You are flat WRONG. You get 2 digit codes or 3 digits codes, not both.

 

Over the last 6 weeks I have found numerous references for Ford OBD1 trouble codes for the EEC-IV that support 2-digit and 3-digit codes. Please document for me that it is an either/or situation for the codes; somewhere there is a mis-communication since counting flashes of my Check Engine light is pretty simple. I've used the documentation at the link below as one of my references to verify codes 55 and 56 in the first set of codes and 512 in the second set codes (the long-term memory codes)
http://www.troublecodes.net/Ford/

 

It's a common misconception that happens quite often on this and many other forums. Yes there is documentation for 2 and 3 digit codes. But that does not mean the vehicle will display both. It's either one or the other.

A few recent examples:

https://www.ford-trucks.com/forums/1...the-death.html

https://www.ford-trucks.com/forums/1...150-codes.html

https://www.ford-trucks.com/forums/1...-question.html

https://www.ford-trucks.com/forums/1...-not-23-a.html

https://www.ford-trucks.com/forums/1...ing-rough.html

https://www.ford-trucks.com/forums/1...-question.html

https://www.ford-trucks.com/forums/1...250-codes.html

Cut from the Equus 3145 Ford Code Reader Manual:

Ford Diagnostic Trouble Codes are composed of two- or
three-digit numbers.
* Most early model Ford vehicles (up to 1991) use a two-digit
code system.
* Most late model Ford vehicles (1992 to 1995) use a
three-digit code system.

Full manual available here: http://www.equus.com/Content/Support..._20NOV2002.pdf