I am having problems getting my truck to start. I have a
90 f150 with a 5.0. The engine is turing over but the only time
it will start is when you hold the gas pedal to the floor. After it
starts if you let off the gas it will die but if you hold the gas down
for a few min. it idle. Also when it starts it has black smoke coming out of the exhaust. I have already replaced the control
module. please help.

 

If memory serves this truck is equipped with an EEC IV ignition and port FI. It is obviously getting way too much fuel. Holding down the pedal is the clear flood mode and shuts off the injectors, but yours keep pumping fuel for some reason. Check to see that the fuel pressure regulator has vaccum. Give it a big vaccum leak, stay off the pedal and crank it. might start and go ballistic so be ready on the key. I can't beleve that your injectors would all go bad all at once and I don't think one bad leaker would give you so much trouble. Injector pulse get its signal from the pick up and the TFM on the distributor. You already adressed the module, did you happen to change the pick up too. It produces a wave signal used by the module. I guess if it went wack it could fire the injectors and the plugs double time although I have never heard of this happening. I still want to think fuel pressure or injectors. wish I could be of more help. Let us know!!

 

Check your IAC (Idle Air Control Valve).

 

hi there! you know im having the same problem with my '89 f-150 but mines got the 300 I6 in it.its hard to start(but mine dont start)and when it does its black behind.try turning the key to the on posistion,wait for the fuel pump to shut off,turn the key off then back on again and so on. let the fuel build up pressure then try to start it(the more you do it,the more chances it might stay running) if it does start and idle its your low(in tank)pump.now check your fuel pressure regulator. take off the hose from the regulator and turn the key on and have somone watch the reg. if it pumps out fuel out of where you disconnected the hose from, your pressure regulator is shot. oh yeah take out the plugs and see if they were black like mine were!!!

 

Black smoke= rich mixture
Blue smoke= Oil
Gray smoke= moisture(water or coolant)

If it is blowing black smoke and is blubbering it is too rich. It is not a fuel starvation problem.