Stumped... overheating? (female learning)

[sheeton]

I have been having one problem after another with my truck, (89 Ford F-150 Lariat 5.8 4X4) and have put several hundreds of dollars (because i guess i can get suckered into buying crap that I dont need) Just to let you know... I am a female, but not completely stupid about vehicles, but I'm stumped. I work about 10 miles from my home, and my truck trys to stall when I stop at red lights or go really slow (in school zones). If I put her in N, she is ok for about 30 seconds, but then i have to rev her a little bit to keep her from quitting. If I rev her too much though, she will stall too. About a month before she started this crap, I was having a problem with my starter not shutting off. In the last 6 months, I have bought: 3 starters, a new battery, new battery cables, starter sylanoid, fuel pump, air filter, vacuum hoses, and i'm sure more, but I dont remember. By the time I get to work (about 45 minutes of slow driving) she wont start when you switch her off. The only person that would talk to me said it's a starter heat shield. anyone know what's going on?

[butch h]

I would,first,find out if there are any fault codes. You said truck would not restart after shut down. Is it turning over? If it is,the problem may be fuel delivery related,if not I would be checking primary electrical connections including grounds. Low voltage at the starter can cause it to keep turning,as could a faulty starter relay. At any rate,a tune up,and systems check is indicated.

[sheeton]

Well, the last time I took her in to a mechanic (about 2 years ago) the only problem that came up was the Throttle Position Sensor. It's burnt on the outside but the prongs are still ok, and he said it wasnt that big of a deal since it had been that way for about 5 years or so now. Could that be the problem now? if so, i would have to get a pigtail too. i cant find the pigtail, but the sensor is about 40 bucks. I really cant spend too much money (i get about 60 bucks to spend a week after my bills). is there a way to test my parts without going to a mechanic and paying 100 bucks to put it on a computer?

[Torch]

You throttle position sensor should be nothing more than a variable resistor, unplug it from its harness...

Here is how to test it:

1. With a multimeter set on OHMS test the two outside prongs it should some to some number, I have no idea what though for your truck (check a shop manual it may tell you), whatever it is write down that number.

2. Put one lead on the center pin and the other pin on the left pin, write down that number.

3. Do the same thing with the center and right hand pin, write down that number.

4. Add the numbers from steps 2 and 3, they should come to the same number that you had in step # 1.

5. Put one lead on the center pin and another on the left pin, have someone SLOWLY open the throttle, the numbers on the multimeter should slowly climb to something close to the number you had in step # 1.

It is probably not going to start out at 0 (zero) due to the idle speed screw, and you shouldn't get any places in the middle where the number suddenly goes to 0.0 ohms or an infinity reading. If it climbs nice and smoothly it is probably fine, if you keep getting infinity readings or the numbers jump all over the place I would replace it.

But to answer your question the throttle position sensor shouldn't itself cause the engine to stall, check a shop manual on how to pull the fault codes out of your engine computer, they will tell you more than anything else what is wrong.

Your starter not stopping is another problem all on its own, your ignition switch has probably gone bad, they have a return spring inside of them that is supposed to push your key back to the RUN position instead of the START position where yours is getting stuck. If you replace your ignition switch that problem will probably go away.

There are also some cars (mainly 1970's Chevy's) where the exhaust pipes went right past the starter and were so close that the starter would overheat itself just sitting there, then the next time you tried to start the car it wouldn't start until you let the engine cool down. They eventually came out with a heat shield to put between the starter and the exhaust pipe to keep this from happening, why no one from that era had the forethought to not put something extremely hot next to an electrical motor is beyond me.

[mrfirebird]

could be the ignition switch causing all the problems being shut off ,shorted