sharper410

I have a 99 F150 with the 5.4 engine. When the engine is cold it starts up with the first turn of the key everytime. But, when it is warm it takes a fe turns of the key and when it starts I get a sort of unburned fuel smell. Any ideas what causes this or what to do to fix it?

C Michael

Check fuel system for leaks when it is at operating temp. Heat causes expansion. Can you isolate where the smell is coming from, ie engine compartment or exhaust. Is the engine running alright? Any other symptoms?

sharper410

Everything else runs great. I suspect the smell is from the exhaust as I get it when I turn on the A/V.

C Michael

Have you checked your O2 sensors? Cat maybe?

sharper410

I put new O2 sensors on this past spring. I'm pretty sure the smell is the unburned gas from when it doesn't start. If I could figure out why its hesitant to start when warm, then it will go away.

C Michael

Have you cleaned your MAF and IAC?

sharper410

I'm still having this problem and hoping for more insight. Seems to be a little worse when its warmer outside.

Mytrucksbroke

Mines doing the same thing. Sometimes starts right up and sometimes takes a little longer to start. Was like that for about a month and now my truck sputters when easing on the throttle. (No matter what speed) almost like a coil prob, but no cylinders misfiring when put on the scanner

biglee88

Weak fuel pump? Check fuel pressure

sharper410

I'm still having this problem. I know the un-burned fuel smell I get isn't good for the catalytic converters and I sure don't want to replace those. I'm hoping someone has some experience with this and can lend some advice. Again, it only occurs when the engine is warm.