Can't start, and can't idle.

[zzb3886]

Hi, I bought a 2000 XLT a short time ago with 100k on it. It's been well maintained by the previous owner. Everything was fine until today. This morning, I couldn't start the truck. I started the key, heard the crank, but it didn't start. On the second try, I depressed the gas pedal to the floor, and it started. It stayed alive when I gradually released the pedal, but died again when the pedal was completely released. Seems it can't idle at all. But it was fine yesterday. Where should I check? Thanks much!

 

[zzb3886]

IAC seems problematic

I took off the IAC. It's resistance is 10 ohms-- should be fine. Applying 12V on it I heard the click but hardly saw any movement. Should the valve be closed when no power supply and open when appying 12V? Thanks,

 

[zzb3886]

OK. I think it's the IAC problem. It was not that dirty, but the valve stuck. I pried it open and the engine can idle now. But the valve still can't move freely when applying 12 V. Guess I need a new one. Or is there a way to fix it?
Thanks.

 

[Rick]

Do a search for "cleaning IAC" on this site. It's been discussed several times.

Welcome to the forum

 

[zzb3886]

Thanks. I cleaned it and put it back. Now it seems OK. I'm wondering how big the movement of the piston should be. When I applied 12V, the movement was tiny, way less than 1mm. But this little movement appears to be pretty important -- if the IAC harness is unplugged, the engine won't start again. Is that normal?

 

[MustangP51]

My guess if it started when the gas pedal is put to the floor that the fuel pump isn't working. When you turn the key you should hear the fuel pump prime for about 3 seconds. listen for it. If you don't hear it check to see if the inertia sensor has been tripped. It is in the right kick panel on the passenger side floor.

 

[MustangP51]

Thanks. I cleaned it and put it back. Now it seems OK. I'm wondering how big the movement of the piston should be. When I applied 12V, the movement was tiny, way less than 1mm. But this little movement appears to be pretty important -- if the IAC harness is unplugged, the engine won't start again. Is that normal?

Ok, disregard my last post lol.

Yes the IAC moves very little, and I have never tried to start the engine with the IAC unplugged so I cant help you there.

 

[zzb3886]

Thank you. Now I know what that 3-second sound is.

 

[Sams01XplrSprt]

welcome

 

[BrooklynBay]

Welcome to this forum! Cleaning the IAC should work, but it eventually might go bad just like any other part.

 

[tlhorine]

What is an IAC. I had taken my teen daughter and 3 other girls to thier HS football game. The car started gurgling and shut down. I could start the car and all would work, lights,radio air etc. For some reason whenever I went into gear (Drive) I shut down again. I called a mechanic who had replaced the joints for me ( frantic that I had young girls inthe car) He told me to leave the car in P and rev at 2 to 2.5 which I did and then slowly go into drive. I was able to get the vehicle to a safe neighborhood by driving with my foot on the brake and the gas (as instructed) I kept blowing my horn and blinking my brights as I entered stop signs or intersections. I was not at all comfortable driving like this....My vehicle has been at the mechanics since Friday night and I have not heard nor have they given me any idea of the issue...My oil is always changed before 3,000 miles , the starter,belts and battery were all new in early 2007... Any ideas?

 

[BrooklynBay]

Welcome to this forum! The Idle air control is the main control valve for controlling the idle by varying the amount of air entering the intake manifold through the throttle body. It's an electric solenoid which is computer controlled.