I am not very familiar with Ford fuel injection, as most of the vehicles I have owned are carbureted. I have a 96 F150 with the fuelie 300 six, with MAF. As the weather has gotten hotter I have noticed the truck is starting much harder than it did when it was cooler outside. The engine turns over fine, but I have had to crank it 2 or 3 times before it starts. Sometimes when I try to start it, it will spit and spudder and barely hold an idle. Sometimes it will stall out, sometimes it will rev up to the normal idle speed. If I step on the accelerator to keep it running it makes no difference. Typically when this happens I get a strong raw fuel smell once it starts. Can any one give me some insight on what could be wrong here? BTW once the engine starts, it purrs like a kitten.

 

Sounds like perhaps an injector is bleeding down into the engine when it is not running. Also, is the blower for the injectors working? Many 300 I-6 EFI engines have a blower that blows onto the injector area to prevent vapor lock.

 

Bleeding injector? Hmm didn't think of that... wouldn't that give me problems all the time regardless of temp or weather? Also wouldn't I find gas mixed with the oil in the crank case? A buddy of mine thinks it might be the IAC or an air temp sensor. Does that seem possible?

 

Sorry to say, but I work on Honda cars to pay the bills. Anyway, I remember service bulletins linking similar problems (especially after a hot soak) to the amount of alcohol in the gas. It would vaporize in the fuel rails due to engine heat after sitting. Seems there's more alcohol in winter formulation gas, so we usually ran across this problem when the weather started changing. Don't know if your problem is related to this, though. Just something to think about.

 

That's why I asked about the intake blower. Might help the heat soak problem.

 

HMMM vapor lock, never thought of that. Intake blower? Where exactly is that located? Could mine be bad, can it easily be replaced?

 

If it has one, it will be towards the front left of the engine. It looks like a smaller version of the heater blower motor. Circled in red on the left of the picture.

 

Cool thanks LxMan1 I'll have to check into that. I assume this is for additional cooling for the fuel rail and injectors?

 

Yeah, since they sit right over the exhaust, it is supposed to come on for a bit after shutting down the engine hot to keep the fuel rail cool. I'm not sure what all years had them.

 

I think I'll pop the hood this morning to check the oil, meanwhile I'll look to see if my truck has one. I would think that being it's a 96 it would have that blower.

 

I thought the later year 300s replaced the blower with just a heat shield?

Its possible the spark module on the distributor is going out, or the fuel rail is bleeding down. Get a fuel rail pressure gauged hooked up, fuel pressure should hold even after you turn the key off

 

I would change the IAC. I had a similar problem in a v6 Ford Aerostar some years back, and it cured hot weather issues immediately. (At one time on a 105 degree summer afternoon, I had to come home in a van that would not go over 25 MPH with the pedal to the floor. Very frustarting.

Also, I wrapped my exhaust system with Thermo-Tec header wrap. Best thing I ever done. It cuts underhood heat by half, at least, protecting many engine parts (starters ect. ) from unecessary high heat conditions.

In the winter, it insulates, and you enjoy toasty heat on chilly, foggy, early mornings, nearly immediately. The pipes hold more heat, which helps make more power in the combustion chamber. Not a huge difference, but it's more effiencient at it. The engine takes longer to cool down, which is a benefit, because there is more ambient heat inside the engine as compared to one that is stone cold. This allows the oil to remain warmer longer, the coolant, ect. It's a win-win situation all around.

I've had the wrap on for at least 55 K now, with zero problems. Just some thoughts.

Ed