I have an issue with my 86 short wheel base F-150. It has a fuel injected 5.0 and a C-6 trans. Here is what is going on:

- Start the truck in the morning, and it starts up as normal.
- Ran the truck down the road about 25 miles and parked it for 4 hrs
- Went to start the truck again after sitting for 4 hrs and it would just crank and crank until I put the pedal to the floor and continued to crank. Then it will start up and smells like it is running rich.
- Drove it for about 2 miles, shut it down and tried to restart after sitting for about 20 minutes. The truck will just crank and crank with no start.
- Tried to hold the pedal to the floor as before and it will fire and die.
- Tried to put some gas in the gas tanks thinking it didnt have enough in it or because it was parked slightly at a downward angle that it wasnt getting enough gas - no change.
- Eventually killed the battery. Let it sit for about 20 min and got a jump. Held the pedal to the floor and it started and you could see rich exhaust smoke coming out of the tailpipe.
- Drove it back about 25 miles to home, put it in park for about 2 minutes while moving the other car so I could pull the truck in the driveway, got back into the truck, put it in reverse and backed up about 10 feet, put it into drive and it died again.
- Gave up on trying to troubleshoot as I was too frustrated to continue.

Here is what has been done to the truck so far:

- Stock 5.0 with newer coil, new Accel cap and rotor, new Accel 8mm wires, new Motorcraft copper plugs, new TFI module. Cap, rotor, plugs, wires, and TFI module replaced last month and only have about 100 miles on them.
- Replaced front tank low pressure pump about 2 months ago.
- Replaced fuel pump relay about 2 months ago.
- Replaced valve cover gaskets about 1 month ago.
- Replaced the IAC.
- Timed the truck to ~ 11 degrees BTDC after replacing all the things above. And yes, I set the time with the spout connector disengaged.

Things to note:

- Key does not "bounce" back to the run position after going to the crank position. Need to drop the column and fix this.
- Havent pulled or tried to pull codes yet. Plan to do this soon.
- Havent checked the plugs to see how they are burning.
- Checked the vacuum line on the fuel pressure regulator for any gas seeping by and did not see any.

Anyone have any suggestions/recommendataions?

 

Check your fuel pressure after you shut it off. I bet it drops quickly. It should hold for a long time. I suspect some of your fuel injectors are leaking. When it sits, the fuel injectors are dribbling fuel into the engine and flooding it. Holding the pedal to the floor while cranking puts the computer into a "clear flooded engine mode" and turns the fuel off to the injectors, so that's why that is helping you start it. Does it idle a little rough when you do have it running? That's another sign the injectors are sticking, and not spraying the fuel into the cylinders evenly.

 

My only suggestion is to pull the codes, and let the computer tell you what it thinks is wrong..

 

OK, finally had time to pull the codes from the truck. Here are the codes:

KOEO:
51 - ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
24 - ACT sensor out of self test range 0.3 to 3.7 volts.
87 - Fuel pump primary circuit failure. When the FP relay was activated by the EEC, voltage was not detected on the control circuit.

KOER:
21 - ECT out of self test range 0.3 to 3.7 volts.
24 - ACT sensor out of self test range 0.3 to 3.7 volts.
41 - No HEGO switching detected always lean (right side
34 - PFE or EVP circuit has intermittently failed above the closed limit of 0.67 volts.
77 - System failed to recognize brief WOT during Dynamic Response Test (user error).
25 - Knock not sensed during dynamic test.

I think I will try the KOER test again since I didnt let it really warm up (2000 rpm for 2 minutes) and I didnt do the WOT. But, what is alarming is that my ECT and ACT sensors are failing. How can I check the ECT and ACT circuits? I am assuming that they are 5V supply sensors. Any suggestions?

 

if it cold out, they will read as failed. They are easy to pull and check, and its usually pretty damn obvious if they need replaced. They look like they have been sensing turd temperature in the sewer system for 15 years, best replace them. My 5.0 did the same thing until i replaced them, i had the same codes, pulled both those sensors out and was like DAAAYAAMM now mine starts fine all the time.

 

btw they can be checked with a good ohms meter, but the reading will be dependent on temperature. There's a graph somewhere for them but i dont recall where, might try google search, i think there may be one on mustang forum. But pull them out and check them for sludge. Sometimes they fail and they think you have a cold motor when you dont, so they richen you up and it hard starting warm. I fought that for 2 years before i found mustang forum.

 

I'm so glad my truck is carbureted and I don't have to deal with this stuff. As if carbureted engines are fool proof.