87 efi 300 l6 4.9l runs fine the black smoke comes out the tailpipe???

[baul1]

Hi I have replaced all my sensors changed plugs and wires timing is set at 10 fuel pum is pumping fine. Replaced egr valve and sensor. could it be the fuel regulator??? or the idle air valve??? it will run fine then trys to stall and black smoke comes out then give it gas and it will stop and run okay again. i unplugged my battery and computer for 1 hr but that did not help. it was running fine but then it just startred acting like it was running out of gas sometimes then it would be ok. gas mileage is baddddddd. i know it is going out the tailpipe but why? I ran a code scanner and everything i have replaced shows up again when i test it i thought i was erasing the codes like the book said but i guess not. i am stumped please somebody helpppppp meeeeeeeee. Thanks to all of you that reply. Oh i am new to the forums so please bear with me.

Tim hoffman
farmerville, louisiana
1987 ford f150 4.9l fuel injected 300 inline 6

[ModMech]

Yup, it sure could be the fuel regulator, or a bad coolant temp sensor, vacuum line to the BARO sensor, leaking (bad) injector, or a bad EEC.

Usually with black smoke, it is something obvious and simple.

[baul1]

thanks modmech i already replaced the cts. checked the vacum lines. guess i will try the idle air valve next when i get paid. then the fpr. thanks again

[fordtrucksonly]

That seems like a fuel regulator, my buddy had a simular froblem with his 85.

[baul1]

Hey fordtrucksonly thanks i just replaced the ildel air no luck so i am going to get a fpr. thanks again i will let yall know how it goes. later folks

[baul1]

i unplugged the computer and battery after replacing the idle air it seems to be running good now but the idle speed is too high. i have the timing set on 10 it was on 0 when i checked it when i didn't know what was wrong with the truck. 10 is what is written under the hood. any ideas guys??? thanks later folks

[badasstour]

change your cats