I have a 91 Ford F-150 XLT Lariat. Original 72,000 miles, 5.8l 35. I've been a mechanic for 30 years and this old guy has me stumped! I put a high pressure fuel pump in line just to make sure it is getting fuel. My fuel pumps in the tanks are also working great! I have checked the spark at the coil and at all 8 plugs! it is getting plenty of spark! I have ruled out spark and fuel issues. I have a feeling I'm missing something. It did sit for 12 years in a barn. The tanks look new inside and out! I doubt it's an injector problem because it tries to start with just the fuel pumps or me spraying starting fluid. What the hell? Thanks!

 

Did you actually measure the fuel pressure off the rail? Specs call for 30-45 psi. Hearing or saying pumps work great is meaningless unless it's getting to the injectors at the proper pressure..We need facts.
You need these for it to run:
Spark, fuel , compression and air. If you are getting good fuel pressure to the rail, check and make sure the injectors have power and also being turned on by the computer grounding the other injector lead when it's time to turn on.. If you have all that "confirmed", maybe a compression check is in order to check for a jumped timing chain.

Considering the age of the truck and it has sat for a long time, I would look closely at the ECM. Pull the cover off and look at the three electrolytic capacitors. Any leakage or bulging is reason to replace all three and can cause fuel issues.

 

Compression is all over 120. The truck has 40 psi of fuel pressure and very strong spark to each plug. I have checked all of this 3 times now. The truck wants to run, you can hear it trying to fire and almost does. This is probably the issue? I just pulled the ECM.

Maybe this is the problem?

 

Sitting for 12 years, I would double check the condition of the pump strainer
I would also take a fuel sample from inside the tank before it goes through the strainer or filter
Sometimes when they sit, the inside of the tank can "look" clean
But after filling with new gas and driving around a bit, the crud in the tank gets mixed in with the new gas
3 fuel pumps later you put a new gas tank in it

 

Yep the green capacitor on the right

 

Replace all 3 capacitors

 

See if you can find a good one at the JY, getting them online can be a bit tricky. It is best if you can get one with the exact catch code, which is the 3 or 4 letter/number code generally in the middle of the connector. HUG0 in this case.

 

I changed the ECC, compression is normal, strong spark at every cylinder, good fuel pressure, I'm even spraying starting fluid right into the throttle body. This thing wants to start but doesn't. It makes no sense to me! Spark, compression and fuel. What the heck else could it be?

 

Perhaps I missed it scanning through this thread, but has the timing been verified? IIRC, should be 10 BTDC with the SPOUT connector pulled out.

 

No, but this truck only has 72,000 original miles on it. Do you honestly think it jumped time? I've turned to distributor and get nearly the same results.