Look'n for bluegrass
 

Hey friend!
I posted last week

Hi. Having problems with my F150 4.9L. Will start and idle fine but when I take off it will sputter and blows black smoke until it stalls or cleans up and power returns. Only to happen again at the next stop and take off. If I let the truck run for 15m or so the problem is gone. ect.

You gave me this.

There are a number of things that could cause this and a fuel filter in not one of them.
The fuel pressure regulator allowing to high a pressure.
The OX sensors are very slow reacting (the heating you mention) helping.
The ECT and IAT faulty. These still have a large effect on fuel at all times.
Any fault that suddenly makes the injection go very rich (the black smoke).
You should have a fault code stored with this kind of problem.

I tested and got back a code 118 ECT high or open. What i need to know is what and where is it! I'm sure it's a dumb question! but I don't know till I know. Thanks to all!

118 ECT= Engine Coolant Temperature senor.

The sensor is a temperature sensitive thermister that lowers it's resistance with increaseing temperature.
If it is open or very high resistance, the PCM considers the engine temp very cold so dumps a large amount of fuel thru the injection like winter time.
Later on, the PCM sees the resistance still high and considers it a fault.
This sets the code 118 and subs it's own internal resistance value so the fuel injection level comes back to a reasonable range to keep the engine running since this is not a real catastrophic failure, hence the problem 'seems' to go away but really did not, only to reapear again when there's enough of a cooling period that the PCM keeps trying this circuit for 'expected' action.
This is how an intermittant would be handled if say the cable were going open etc.
See how much common sense there is to all this from a design stand point?
What year is the truck? There are small differences, so someone can tell you for exact location.
Good luck.

I had one of those go bad on my 88 302. Thing damn near got me killed a couple cold mornings. When the truck died on take-off it wouldn't re-start. Left me trying to push it out of an icey intersection twice before I figured out what was causing the problem. Changed it out and it solved the problem. Like 6 bucks I think.

Easy change on the 302 don't know about the 300 though. Good luck.

WOW - Thanks again Bluegrass!! :bows: It's a 1994 if that helps. And WVtrucker same thing happend today to my wife. It died when she pulled on belmont st.Its 2 lanes North and South. Not a good place to stall in the morning. She called me when she got to work....&%$#@%$& and again when she got home ......damn thing almost got me killed to!!!!

Sorry to hear of the near misses.
A further note on the ECT is that often with an open condition exist, starting will be difficult or impossible on a Speed Density (non-mass air) type engine control the older engines have.