1988 Ford F150 lariat, 5.0L 302, Automatic, 4x4 single cab short bed, 56k miles

This truck sat for a few years, and no doubt both front and rear fuel tanks are 100% full of rank gasoline which now looks and smells like a very dehydrated person peed in some diesel fuel. I'm working to get this thing going. My dad replaced the high pressure fuel pump thinking this was the issue. I acquired the truck and have tested both the old and new inline fuel pumps, they're both fine. The two pumps in the tanks have failed, and I'm in the process of replacing those as well. The truck cranks over and is getting spark at least to the distributor, and all systems work except for fuel.
The problem: The EEC relay comes on with ignition as it should, providing 12V to the Fuel Pump relay coil, but no fuel pump power because the FP relay does not close. This is due to the second leg of the coil having 10+ volts from the ECU (pin 22), which creates almost zero potential across the fuel pump relay coil, not allowing it to operate. The computer is supposed to ground this leg on pin 22 to allow the FP relay to fire the fuel pumps. This happens when the ignition is turned to on, and it runs the fuel pump for 1-2 seconds, and it also happens when the computer receives PIP signals from the ignition control module signaling that the engine is cranking and needs fuel. When I short his wire on pin 22 to ground, the pumps kick on like they should because the FP relay closes...I get 12 v to the inline HP pump and to the tank pumps (I measured all three sets of wires for the pumps to make sure). Why wont the computer do it? Being that the fuel pumps run from the FP relay, I know my tank selector switch is good and the inertia switch is healthy.
Has anybody experienced this? I found the black wire from pin 6 for the computer ground to be unhooked somehow, it is now cleaned and securely grounded with no change to the fuel pump situation. I've attempted to chase the orange wire from pin 49 down but I don't know where it's supposed to be landed so I cut into it to verify bonding and it is connected to negative somewhere. Tonight after work I'm going to check pins 40 and 60, as per another fuel pump wiring diagram they show that they are to be connected to the negative on the battery post. Is there anymore? Maybe someone knows where that orange wire goes? I can't get codes from the truck because It has sat too long without a battery and won't run to throw any codes. I'm hoping in my dad's efforts to get it going that he possibly pumped some bad fuel to the fuel pressure regulator or something and it's now rotted and plugged off. If that is the case, is there a fuel pressure sensor that could be failed high, telling the computer not to run the fuel pumps? Are there anymore tests I can do before I go on a painful hunt for a new ECU?
Thank you in advance to everyone who takes the time to read/reply to me. All the help is appreciated.

 

I should also mention that the ignition coil is successfully providing spark to the distributor.

 

Your symptoms lead me to believe you have a bad computer. Even though the battery has been disconnected you can still run the Key On Engine Off (KOEO) tests. If they pass you will get System Pass Code 11 (displayed twice). Then the computer will go on to display any stored codes from Continuous Memory(CM). If there are no stored codes you will get System Pass Code 11 again. Given the age of the computer I would suspect the capacitor(s) inside the computer has gone bad.

FYI...there is no fuel pressure sensor to tell the computer what the fuel pressure is. The computer is hard coded to trigger the fuel pump relay for 1-2 seconds every time the key is cycled from the Off to Run position.

You can verify the fuel pump relay energizing circuit is good by jumpering Pins 2 & 6 of the data link together then turn the key to the Run position. This simulates the low applied by the computer. If the circuit is intact the fuel pump(s) will run continuously until you turn the key to Off.

 

Thank you rla2005. I really hope it's not a bad computer, but if it is, maybe it's possible I can solder in a new capacitor. I have a bunch of other work to do on this truck to get it going, so for the mean time I may just run with the fuel pump relay shorted to ground so I can at least get fuel and get this thing running (if it will). FYI - I have not actually used an OBD1 tester, just the shortcut of jumping the test input wire to the self test return pin #2 on the data link, and waited for signals from the check engine light, but nothing. Perhaps I'm doing this wrong, or your correct that my ECU is trash.

 

Try grounding the STI pin to a known good ground. Perhaps the data link ground is bad?

Another quick test is to verify the Check Engine Light (CEL) turns on when cycling the key from Off to Run. Some have reported their trucks of this vintage did not have a CEL lamp from the factory. Others have found a PO removed said bulb....

 

rla2005 - Thank you again for your input. I will verify the STI pin to ground continuity. I do know the CEL is working, I can see it when cycling the key in the ignition. It is very dim, so perhaps I have a wiring/grounding issue there as well, but it is there.