Hello all, newbie to the forum looking for help. Have read lots here but can't find and answer to my problem. We bought an '86 F150. 302/auto. Fuel injected. 4x4. Bought it as a non-runner. It cranks fine. Has spark to all spark plugs. Put a gauge in place of the schrader valve. Have 40 pounds of pressure. Previous owner replaced main fuel pump and inline filter. We changed and cleaned the canister filter, pulled and cleaned the fuel injectors. Two of them were completely fouled. They are all squirting a good spray pattern. One thing there, everything we read said 1.5-3 volts should fire the injectors but it took a full 12 to get them to fire. Stands to reason I guess since there is 12v sitting on the red wires to them when they are installed. Tested the EEC relay and it is working as it should. Pulled codes. The only one it showed was 22. MAP out of range. Not sure if it is old because the MAP is new. The rear fuel tank is missing. There is not an injector cooling fan on the truck. Have checked grounds. Ohmed wires looking for breaks. We checked the TFI module and found no signal from pin 5. Pulled it out and had it checked. Failed at the parts house. Replaced it but still no start. Spark plugs are dry as a bone. New cap, rotor, plug wires (8mm). Can hear the fuel pump run initially when we turn the key on. We are at the limit of our knowledge. Our multimeter doesn't measure in Hz so can't check anything that way. Long winded but I'm sure there is something I forgot to say. Thank you for your help.

 

Pull the battery cable off for a minute or so, and then re-install it. Then pull the codes again. If you still get that 22 I would investigate that further.

 

I would also check the sensor inside the distributor; this is, in effect, a crankshaft position sensor but Ford calls it something else, PIP or some such. Regardless, the computer sometimes won't fire the injectors if that thing has failed.

 

Ok we pulled the negative cable off for about 30 min and retested. Still pulled 22. Going to get a multimeter that measures Hz to test the MAP. Checked for the PIP signal and it is there. What signals are required by the PCM to fire the injectors?

 

If the computer wasn't getting pulses from the dist, it "should" give you a code for that. Probably a 18 or something related.

 

Checked out the MAP with a meter. The frequency reads where it should and decreases as vacuum is applied. Can't get the code to clear from memory. Left the cable off overnight then pulled codes without trying to start it and code 22 is still there. ECM is supplying 5v to the MAP. Haven't traced the signal wire back to the ECM yet. TPS is correct. PIP signal is coming out of the TFI. Checked the power and grounds to the ECM and they are good. Just not getting the signal to fire the injectors. Frustrating. Has anybody fixed a problem like this or is it time to go old school and put an intake/carb on it.

 

The fuel injectors should always have 12V on the RED wire when the key is in RUN position. The computer provides ground for a pulsewidth modulated signal on the other wire. Hooking straight 12V to them will burn out the coil if left for too long. You can use a 9V battery to test injectors, just by tapping the contacts not leaving voltage on.

TPS output is reading less than 1V, correct? Dark green positive, orange negative. If reading too high it'll go into "clear flood" mode and shut off the injectors. TPS 5V for pretty much all the sensors comes from the same place on the PCM. Ground for TPS, MAP, and EGR position sensors all come from same point on PCM.

 

SSellers, yes the TPS has .93v and 4.8 at WOT. Can't find what all signals the PCM looks for to fire the injectors. All tests that we have found so far have passed. Still haven't traced the MAP sensor wire back to the PCM yet. Thanks for your help.

 

It runs! Thanks to all who tried to help.

 

And the problem was....?

 

Not sure what was wrong. Got tired of chasing our tails. We checked for continuity of all signals going to/from PCM. Tested all sensors. Pulled and tested all vacuum lines. Checked fuel pump and relay operation. Disconnected and cleaned all connections with electronic cleaner. Verified all grounds were good. Basically did a hand over hand of the entire EFI system. Put it all back together and with a little coaxing, it fired up. Turns out the truck has sat for about 7 years. Oil pan is leaking like a sieve. That's next on the list. Learned quite a bit about early Ford fuel injection. Now if only we can have the same luck on the Powerstroke we picked up, we'll be happy.

 

The old "take it apart and put it back together" trick. Works more times that you would think. The wiring and connectors are getting very old in these trucks.