Model: 1986 F-250 XLT Lariat
Engine: 7.5L / 460 Gas
Transmission: Automatic
Electrical: Single Battery, Factory AC

HISTORY:

About a year ago I had the engine and transmission rebuilt. The distributor, alternator, power steering pump and starter were all replaced. The truck ran perfectly until about a month ago when the engine started turning over slowly when starting the truck, as though the battery was going dead. The battery tested weak so I elected to replace it to eliminate the battery from the equation, which did not solve the problem. The slow starting problem became progressively worse. When trying to start the truck the engine would barely turn over then ultimately start. Before I had the opportunity to troubleshoot the starter my son borrowed the truck for the day. While trying to start it he wore down the battery so he called AAA to give him a jump. He said when he tried to start the truck with the AAA truck jumper cables connected the starter would not turn over and he saw smoke coming from the area of the battery so they disconnected the jumper cables and towed the truck to my house. I asked him if the jumper cables were connected to the correct battery terminal and he said yes.

I inspected the battery area where my son said he saw the smoke coming from but I wasn’t able to locate any burnt wires. I did however discover the negative battery cable had a poor connection to the engine block, which I suspect may have been the cause of the starter problem all along.

I replaced the starter with a factory new starter, the starter relay, and all the battery cables. I wasn’t able to locate the OEM negative battery cable that is a continuous cable that runs from the battery clamps the frame and then continues to the engine block. I ran a new negative cable from the battery to the engine block and a separate short negative cable from the engine block to the frame. Life was good; the engine turned over normally and ran like a top.

Two weeks ago I took the truck to the AC shop to check for a leak since the AC started blowing warm air. The AC shop found a line leaking so they made a new line installed it and completely cleaned and recharged the system. Once again the truck was operating perfectly with the AC on and off.

Note: The AC worked fine after the rebuilt engine was installed but over time the Freon leaked out.

CURRENT PROBLEM:

While driving my truck the other day the engine shut down suddenly, as though I turned the key off. The truck had no electrical power at all, the headlights, dome light, and horn did not work. I think it shut down a few seconds after I turned I on the AC. I don't think this is related since the truck has been running fine with the AC on for a few days after having it repaired but, I have been wrong more often that I am right.

The first thing I checked was the battery voltage at the battery and battery relay terminal, no problem there. Hoping the problem was a fuse I replaced every fuse in the fuse box, which did not resolve the problem. The next thing I did was look for a burned fusible link. I located two fusible links attached to the battery relay; each one had a rubber block in line on the wire. I think one was marked 16 amps and the other 20 amps but I am not sure. To check the fusible links I used my self-powered continuity light. I inserted a probe into the wire about four inches on each side of the rubber blocks. The light illuminated when I checked each fusible link but I am sure if I checked them correctly and/or if there is another fusible link somewhere else in the electrical system I can’t find.

Sorry for writing a novel but I am hoping by providing as much information as possible someone can send me in the right direction to get up and running again.

Thanks in advance

 

Take your testlight and poke around in the fuse box. Does the testlight light up with any fuse in the fuse box?

 

Dave, I will take a look this afternoon and et back to you. I was in hopes my post would be viewed by someone that has experienced a similar problem with their truck or tell me if there is another fusible link somewhere I am missing.