i have a 1987 f150 300 cu.in. 6cy. that has new distributor cap and roter new plug wires and plugs new fuel filter and primary pump new coil.and the thing still won't crank.the service manual isn't much help.engine turns over great good and fast.it is getting fire.

 

Hi, this is my first post. I'm not a mechanic, but I do some work on my vehicles. A few years ago I had the same truck as you have now, same year and engine in 4x4. It developed a problem in that it would be running fine and then just quit, just like the ignition switch was turned off. It would turn over fine, just not start. The problem was with the ECU (I think that was it) relay that is located in a box mounted in the engine compartment on the drivers side fender near the front of the truck. If you have a voltmeter, you can check to see if 12 volts is there to energize the relay, or you can just jumper the relay with a paper clip (like I did) and try to start the truck. If it is the problem, it's a pretty basic part, only about $10 or less at a dealer or parts store. Hope this helps.

 

Hi, this is my first post. I'm not a mechanic, but I do some work on my vehicles. A few years ago I had the same truck as you have now, same year and engine in 4x4. It developed a problem in that it would be running fine and then just quit, just like the ignition switch was turned off. It would turn over fine, just not start. The problem was with the ECU (I think that was it) relay that is located in a box mounted in the engine compartment on the drivers side fender near the front of the truck. If you have a voltmeter, you can check to see if 12 volts is there to energize the relay, or you can just jumper the relay with a paper clip (like I did) and try to start the truck. If it is the problem, it's a pretty basic part, only about $10 or less at a dealer or parts store. Hope this helps.

 

You can someone crank it and check the ignition timing (timing light). If that is in good shape. Key it on a couple of times, turn off the key, and depress the schrader valve on the fuel rail. You should have a pretty good little spurt of fuel. If not, think about the pressure regulator.

Past the fuel pressure it would be the signal going to the injectors. Put a hose on one of them to listen to see if they are firing.

 

Nice answer....

Ford had this problem for years. No matter where they put it, it seemed to get water damaged and rot the terminals out.

It is called an ECA relay, and is responsible for the power supply to the Fuel pump relay, Ignition coil,and Injectors.

There is also an INERTIA switch , which interrupts fuel pump power in the event of a collision.They can become defective, and on more than one occasion ,I have seen them "TRIP" from slamming a door too hard.

 

Thanks For The Reply It Is Sunday And I Cant Do Anything Today But In The Morning I'll Try Both Suggestions/.if They Work I'll Let You Know Thanks Again To All Who Replied. I Am No Mechanic But I Like To Tinker. This Old Truck Is My Garbage Truck But I Find It Hard To Get Rid Of It