I have a 97 F150 4x4 with the 5.4L Triton. I have had it less than 2 months. My son just had to have it. The truck was running too rough to make it home without changing plugs. The plug on cylinder 4 had ejected at some point when the pervious owner had the truck and we had to take it to the shop to have everything on that cylinder fixed and the plug and coil replaced. At this point we have replaced the plugs, coils, MAF, and the 175v maxi fuse (due to it arcing and blowing one side of the fuse because there is no cover on it and it wasn't taped up to prevent it from touching anything). Now the truck will not start unless you are pumping the gas, hold your foot on the gas until the idle level comes up, and then when you shift into reverse, the truck will stall and you have to repeat the procedure again. No dummy lights on, but the auto parts store scanned the truck and came back with the codes P0354 ignition primary 4, P303 misfire on 3, P0306 misfire on 6 and B1932 driver air bag (which is new). All plugs and coils have been replaced. Since the issues cranking and stalling have started occurring, there is now a strong smell of gas and whitish smoke coming from the exhaust and it is using an extreme amout of gas. There are no visible leaks that I can see. After you drive for a while, the smoke stops. It is just primarily after you finally get it to start up and the first little while of driving. I am at a loss as where to go from here. Please help and thank you in advance.

 

Seems like multiple gremlins, check the Crank shaft position sensor and its connection.


Clearly someone has been in there before so a thorough inspection of connections and wiring

check for vacuum leaks , clean and or replace the IAC

 

Typical symptoms of either a sticking IAC valve or of a severe vacuum leak plus....more.

What did the mechanic use to repair the blown #4?

 

Sticky injectors?

 

The paperwork from the mechanic says "remove and install Triton time cert #4 and install plug and coil."

 

Good, he used one of the highly recommended inserts.

The "strong smell of gas and whitish smoke coming from the exhaust"can also be caused by a severe misfire and/or a vacuum leak.

 

My son is drove the truck this morning and he said that it is not running rough, didn't stall when in reverse and didn't smoke. He is going to the mechanic as we speak and it has started doing everything all over again. Someone told him that it could be the fuel pressure regulator?

 

Checked for vacuum leaks and couldn't find one, but the engine compartment smells like gas when it is cranked. Still having to pump the gas pedal to get it started. I am leaning toward fuel delivery. It is acting like the motor is not getting enough gas to start.

 

Remove the vacuum hose from the fuel pressure regulator. If it's wet with gas, replace the FPR.