Ford: loading up on gas, vacuum leaks, engine vacuum

Question
QUESTION: Yes I have a 1986 ford f150 302 efi changed a few parts like egr temp sensor cap rotor fuel filter checked fuel pump its good will the air control temp sensor make it run bad cause I unplugged it and it made it rin worse I don't know what else to check. PLEASE HELP! Thanks

ANSWER: hello.


I'm not sure what your complaint is.


Is the truck running poorly?

Let's start with the basics.

1.Is the CEL (check engine light) on?

What codes are stored in the PCM.

2.What is the fuel pressure
KOEO and KOER

3. engine compression.

4.exhaust back pressure

5. state of tune-up and ignition timing
6.engine vacuum at idle.

7.tested for vacuum leaks


get me as much of this as you can and we'll see where that leads us.

---------- FOLLOW-UP ----------

QUESTION: Oh sorry been a long week but its got a rough idle and lots of black smoke out the exhaust the emissioins light is on which is the check engine light there is only fuel pressure when you turn key on and when you turn the key off there is no gas coming out of the check valve like the injectors are stuck open and vaceum is good and compression is good I will have to send the codes in a little bit not in the shop THANK YOU first person to answer my qhestion and the other sites are a joke thank you very much

Answer
Ok..

On these vehicles, when you turn the key on, the fuel pump will "prime". that is , it will turn on for 10 seconds to chsrge the fuel line.  the pressure (with a guage) will drop a bit, the hold residual pressure a long time. once the vehicle is running, the pump will turn back on.

This is to prevent serious damage that could occur if an injector stuck open or a fuel line broke.