I've got a 96 F150. 300 inline 6. It starts fine when cold. In warm weather, after running only 15 minutes or so it is super hard to start. Sometimes it won't, till cooled down. F&R tanks, fuel pumps both seem to be okay as the truck runs fine when it runs. I'm an old timer without much knowledge of computers, fuel injection & modern contrivances such as "sensors". Is vapor lock possible with the fuel pressure as high as it is in the fuel injection system? Any other ideas as to what my problem might be? Thanks in advance for any help offered. I may be slow getting back to you as I don't move as fast as I used to.

PS---truck starts extremely well when cold, either ambient or truck temp or both.

 

Your starter sounds like it is getting heat soaked and may be on its way out.

 

Define "hard to start."
Does it crank slowly or does it crank normally but not fire.

 

The starter is going great guns. Turns normally. It's getting fire, as it will sometimes start & run briefly on what sound like 2 or 3 cylinders. If it runs long enough, & you can feather the throttle & build some RPMs, it will eventually clear it's throat & run okay. It is definatly a heat related problem & I'm pretty certain it's fuel related. If you hold the throttle to the floor, it will sometimes start. Other time not.

 

You may have leaky fuel injectors.

 

May be that fuel rail heat issue the inline six's are famous for. I don't know much about it since I haven't experienced it, but it goes something like the exhaust manifold heats up the fuel rail and atomizes the fuel or something fancy like that.
It would be nice if steve was around.

 

The heat soak on the fuel rail is not an issue on a 96 as long as the heat shield is still in place between the exhaust manifolds and the fuel rail.

 

Okay my bad, I did not know that.

 

Bought the truck used & don't see a heat shield in place. May have found the problem. Gonna have to locate another 96 4.9 litre & take a look at it. Then see if I can find one on a junk truck. Although that may be hard, as the 300 6 cylinder's seem to run forever. Thanks for everyone's help. I'll be back if that ain' it. I'll be back anyway. An old guy still has a lot to learn.

 

I have a 1996 f150 with the straight 6 engine, i rarely drive it due to working so much, but occasionally when i start it after its ran awhile, it will start but sound like an engine that diesels when shut off, only i am trying to start it. I will usually turn it off then it restarts fine...any ideas would be helpfull.
problem 2... not sure what they do but on top of the engine, i believe going into the fuel injector manifold is a couple of rubber hoses with a plastic junction. the little rubber boots are all dryrotted. could this be a problem waiting to happen. i was told by a mechanic that they were for unspent fuel vapors and had to do with the emissions, and not to worry. any help or replies are welcomed. thanks

 

No.Sounds like it's running rich. I'd check the FPR and both temperature sensors (ECT #56 & ACT/IAT #61).

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If they look OK, keep testing things - there are links in those captions, or just browse the albums.I've never had or heard of a problem with a 4.9L fuel rail.

 

Steve83---I finally found the problem. In tank fuel pump. No understanding of how that could be affected by warm weather/hot engine, but there it is.I much appreciate all the help from everyone. I think I know why auto mechanics make the big bucks. They do magic in addition to turning wrench's.

 

The other captions in the album with that last diagram may interest you. They describe how to R&R the in-tank pump. This album shows the "easy" way to access them:

 

Thanks Steve. From a previous poster I guess you must be the Inline 6 guru. I have driven 300cids for years, both personally & as a service vehicle. I don't know of a better engine. And the LATEST iteration of Ford engines scare me to death. The last generation, i.e. the 4.2 litre, had many problems according to friends who had or have them. Leaky intakes, bad sensors,a recurring problem with the clutch slave cylinder, (ouch). Wish Ford would bring back the old reliable 4.9. Fraid it'll never happen.

 

The 4.9L wasn't even supposed to be a vehicle engine - it's too overbuilt to pass modern emissions.