I have a 77 F150 with the 351M. On more recent occasions when you go to start it you hear the solenoid click and then there is no power. The radio lights nothing comes on. I replaced the solenoid and it did nothing same thing. The last two times it has done this I have taken the positive cable from the battery off of the solenoid removed the two fusable links from the solenoid wait 15 seconds then replace them and it starts right up. I cant figure it out. Anybody have an idea what the heck this might be. Fusable links or the starter relay sticking? After it happens it will run for about a week before it does it again.

 

Make sure solenoid is grounded good. Sheet metal mounting screws don't always do the job. As always when all power is lost, check and clean neg cable to engine block.

 

Have you cleaned your battery terminals and battery cable ends recently?

I have had an issue similar to this in the past. There is enough contact to keep the radio going, lights on, etc but when you go to start the truck the amp draw is too much and nothing happens. If this is the problem it will solve it quickly (unless there is an issue with your battery terminals or cables).

 

I agree, check all terminals and connections. My guess is that they're dirty or corroded somehow, and taking them apart and putting them back together is making a good enough connection at first for it to start.

 

I replaced the positive and negative battery cables. Cleaned the back of the new solenoid and scrubbed it with a wire brush.
The issue with the lights and radio is what blows my mind. CLick and all power goes. turn the key bak on and nothing. Tap the solenoid and it will click again on the start attempt. But it always seems to start after I undo and replace the positive side connections to the solenoid.

 

Still sounds like a bad connection. If all connections are clean, grounds are good and cables have been replaced, than I'd consider returning the solenoid for a new one. Sometimes coincidentally, a new one doesn't always mean good. I'm still thinking there is a bad ground. Make sure the engine to firewall ground is good also. I'm also assuming that the battery is good and fully charged.

 

I know you said you replaced your battery cables, but have you taken a wire brush or "terminal" brush to the posts on your battery? There may be some build up that is preventing your new battery cables from making good contact.

 

Battery and cables are out of the loop. they are all new they were scared up and greased when i replaced them. The only thing that keeps getting my goat is the fusable links. But i will take the solenoid off the firewall and make sure it is grounded again. After I do that I guess only time will tell if it does it again.