I have a 1999 F-150 and i'll be driving along, minding my own busness and the engine will rev-up the RPM's or sometimes it will just stop working. This morning was it. I couldn't get it started. It acts like it isn't getting fuel but there is a half tank of gas. I'm pretty sure that it's not battery/alternator because it gets right on the edge of turning over and nothing. HELP ME!!

 

could be a bad TPS (throttle position sensor)?

 

Seems a little strange to me that this is happening while driving down the road, but who knows? If you are seeing a surging idle, say while sitting at a stop light or in a drive-thru, then the Idle Air Control Motor may be the culprit.

Question about the hard starting. Does it not start at all, or does it start briefly and then die? Does pushing the gas pedal some keep it running?

If it doesn't start at all, disregard. If it starts and dies, or keeps running if you baby it with the throttle, seriously think about replacing the Idle Air Control Motor.

Just my two cents,
Mike

 

What he said.

 

I started to mention the Idle Air Control valve myself, I had a 4 liter Ranger that had one go bad once but like you stated it was only during start up that it would act up. If I could ever get it reved up enough to get going it was fine. I was just glad mine went bad that way, from what I had heard they can also go bad and cause the engine to go WOT at idle.

Off topic, but F151, that Stang in your siggy is gorgeous! I had a '89 GT for a while, which the previous owner had done the 5 lug conversion/Bullet wheels on before I bought it. I think that is about the best looking wheel combo to put on the Fox bodies. One of these days I am going to buy another one to build/play with, but its going to be a LX coupe.

 

Got the engine diagnosed today. All sensors and computer related items are fine. The only thing they could figure was that the spark plugs are very bad and is making it act funny. Along with that, the fuel filter was completely filthy. Who knows. I'll keep everyone interested posted.

 

Ok, we use to have 97 expedition with somewhat of the same problems. We ended up changing the fuel filter, oxygen sensors however if I am correct it was the spark plugs and the spark plug coils.