Hi Guys,

I have a 1987 F150 Custom 4.9L.
I have been restoring the truck and finally got the thing to start after much troubleshooting.
My issue was poor grounding. but everything was starting fine. Started up on the first try, no hesitation.

I got to start it this morning, it kicked once then died. No power anywhere.
I put the key in with the door open and dont even get the annoying buzz warning sound.
The cab light thats on when I have the doors open is off too.

i put my multimeter on each of the fuzes under the steering wheel and they all test fine.
The battery is fine as well.

How do I go about figuring out what "blew"? What can cause power to cut between the battery and the dash?

Denis

 

Hi Denis,
Here we go again !
If,, you ae sure the battery is fine and charged , let's review.

We know you have good clean ground connections from the negative battery post to the engine and from the negative post to the sheet metal, Right !


Now let's look at how the juice gets from the positive post to the fuse panel and everything inside and under the hood.
Positive cable goes from the battery to post on starter relay on the fender well.
Also on that post is 1 and maybe 2 wires that have fusible links in them. Those wires feed the interior fuse panel and maybe something else that may or may not be on your vehicle.With your meter negative lead connected to a good ground , anything you touch with the positive lead that has power present should show 12 volts.
Some fuses in the panel will read 12 volts all the time and some will read 12 volts only when the key is on. As you already know , if the fuse reads 12 volts on one side it has to read 12 volts on the other side of the fuse. Thai is a nice way to do a fast check.
Power possibly goes from one of those fusible link wires to the ign switch.
Getting back to one of the things you said earlier, no buzzing when you insert the key.
The best place to start is to confirm power is available at the fuse panel and either your voltmeter or test lite should be able to show you that.
If you do have power there, a ground for the cab parts is not complete and needs to be confirmed. Simple way is to use a piece of wire, to make a jumper, (temporary path) . If everything now works ,the ground is open and needs to be repaired.
If you do not have power at the fuse panel, one of the fusible links could be open or there is an open in the supply to the fuse panel. You can check for power on both sides of the fusible link by carefully probing the test lite or a straight pin connected to your meter's positive lead. If you find the link has opened, it's purpose is to carry a fairly heavy electrical load for a short time and then open ,thus preventing a wire fire.
If you find the link has opened, now you need too find where the heavy load is and it is probably a direct short . Most likely caused by a wire in the wrong place that is not protected by a fuse or a wire that got pinched in the process of assembly.
Last is my dumb question, did anybody leave the door open or anything on to totally drain the battery?

Don't forget to make sure the battery cables right at the battery are clean and tight !

 

Hey! Thanks again Hanky,

Ill start with the obvious question first. There are no doors on the truck yet, so I unplug the battery as soon as I am done testing things.
I never leave the batter plugged in.
I will see about testing power to the Fusebox.
Stupid question, but is there an easy way to test a wire when there is the plastic over it?
I have a set of alligator probes, those could bike through the plastic if a squeeze the mouth shut over the wire, but I figured that would be a bad Idea.

As for the fusible links, im not sure i am following. is this what you mean?
https://i.imgur.com/mc7z9nM.jpg

Thanks again!

 

OK! so I think im getting somewhere again.
I did a resistance test with each individual wire attached to the ignition relay.
This is the only one that did not flow through.
https://i.imgur.com/8zWoCB0.jpg

Is it because the fuse is blown? or is it because the ignition is off.

 

The square rubber pieces are the molded connections for the fusible link(s).
If it has a fusible link on it , it usually connects to the hot -battery terminal of the starter relay on the fenderwell. Cannot answer how it started before if those wires were disconnected.

 

Ok so I got it started by bypassing the Solenoid.
Once I did, I was able to stop and start it normally... So the solenoid works after the bypass.
(I forgot to close the radiator cap, so it overflowed in the end.)

I just ordered a new radiator cause this one is leaking in one corner...
I am not sure how to seal the leak from the pipe from the heater

 

Den,
The cooling syst operates at around 15LBS press. The rad cap should have a no stamped on it over one of the ears on the top of the cap. Don't remember if that year had an overflow bottle to catch any excess coolant as the coolant expanded after getting warm.
If it didn't , just don't fill the radiator up to the top so you leave some room for the coolant to expand. Sounds good , nice job.
The moisture dripping from the exhausts is just condensate that gets blown out as the cold exhaust warms up, NORMAL in cold environments.