I have a 97 F150 with the 4.6. My problem occurs when the truck is cold and hasn't been driven for a day or so. I will try to start it everything turns over but will not fire. After I cycle the key a few times I can finally get it to start. When it is warmed up it starts and runs great the rest of the day. I have changed the fuel filter which was very dirty and put some chevron fuel system cleaner in the tank. Should I try replacing the fuel filter again to make sure that everything is clean now? Could a new filter get clogged up when the old filter was that dirty? I also heard that a bad IAC could cause cold hard starting but when it starts it idles all right. I don't think it would be a bad fuel pump because it starts fine when it warms up. Sorry for the long post just trying to figure out whats wrong.

 

It could definitely be a IAC problem. Unless there is some reason for you to suspect that there could be a lot of dirt from the fuel tank clogging up a new filter, then I would not worry about that. Good luck!

 

Well I finally got a fuel pressure gauge to see what might be the problem. I hooked up the gauge turned the key to run and the fuel pressure primed to around 15 I then cycled it again and it went to 30. When I started the truck it ran around 32. My question is the fuel pump getting a little weak with that low of pressure when cycled for the first time. Or could it be something else that is causing it not to prime to at least 30. Other than that the pump was right at 32 of so when it was running.

 

I think you've found the answer to your problem.

The second that a fuel filter starts to become clogged the fuel pump has to work harder to supply the fuel upon demand.

You stated that your fuel filter was very dirty. So, it appears that your fuel pump has been working overtime, for a very long time, in order to keep your truck running.

The pressure reading of 30-32psi seems a little low to me. For some reason I'm thinking that the fuel pump should operate in the 40-45psi range. But, I've been wrong before.

However, the 30-32psi might be enough to keep your truck running due to the fact that you have installed a new filter.

I usually change my fuel filter every 10k-15k miles. They are inexpensive, easy to replace, and it's cheap insurance against premature wear on the fuel pump.

Your fuel pump is tired. Have it replaced soon before you're left stranded at a State Park, 120 miles from your house, on a Holiday weekend (my personal experience).

 

Thanks for the replies. I guess I will fork over the money and have my fuel pump replaced. Better to be safe than sorry.

 

Hi I'm having the exact same problem with my 97 f150 4.2. Could you please let me know if changing your fuel pump solved the problem ? I also checked my fuel pump pressure readings and all the numbers seemed to matched with the specs in the manual. I also replaced my fuel filter,plugs,wires,added fuel cleaners,air filter,reg oil changes,cleaned M.A.S and still the same cold start problems your having. Please let me know if your fuel pump was the problem..

Thanks,
Kyle