okay so I have a 1978 ford F150 ranger 4x4 I have had it for a bit and recently drove it 2300 miles from Nevada to Oklahoma. I drove it for about 2 weeks after and then randomly one day I jumped in my truck and tried to start it there was crank but it wouldn't even turn over. So I charged the battery and I replaced the starter because it was long over do. It fired right up 2 more weeks go by and my Girl Friend used to to get to work. She said it would crank but not turn over. I showed up a bit later and I thought maybe she flooded it. So I decompressed the gas pedal and held it down and allowed the gas the equal out the truck then started right up. OH and that's a brand new carb on there as well as all the fuel filters and fuel pump. The next time it wouldn't start was 2 days later it would again crank but not turn over. After that I followed the Haynes manuals and it would seem that it would be my Distributor as I was getting fuel and power to make the crank but no spark. Since then I have Replaced the distributor and the plug wires and the plugs. The truck will crank but wont turn over still I have done every step that the manual has said to do but I am at a loss. My truck has never given me so much trouble before this Please help me if you know or even have any idea what could be wrong with my truck.

 

Check the ignition box, mounted on wheel well. Its either silver or blueish and may have motorcraft on it. Its about 4 inches square. That would be my guess

 

it may also be the fuel pump I know they don't go out often but I just replaced mine. Also if you have two tanks the switch may have went out, where the two fuel lines come together mine went out and it wouldn't switch to the other tank so it just pulled from one tank even though I was switching the switch in the cab. Also could be the starter. hope you can get it fixed

 

Could also help to know your definition of turn over. To me turn over means it wont crank, like dead battery. Some people consider turning over not catching and running on its own.

Biggest thing to know is the 3 things you need for a engine to run, fuel, spark, air. We aint under water so air is a given. When or if it happens again look in carb and work linkage, if it squirts your not getting fire at the plugs. Gotta work your way back until you either find spark or have power. These old systems are very easy if you understand and follow those basic guidelines.

 

You can also crank it and remove one plug wire from a spark plug and hold it against the block and it should spark if not then no power to distributer then maybe ignition box as JayzDaddy says. Hope you find it. Come back and let us all know what happened.Best of luck to you.