What a mess. I have a 1986 F-150 with a 4.9L 300 CID 6 Cylinder with 150,000 miles. The gas milage had dropped off a few MPG so I decided to replace the original distributor cap, rotor and plug wires. I broke one distributor cap screw and stripped the head on the other so I decided to pull the distributor. With the spark plugs removed, I turned the engine by hand until #1 piston was at TDC on a compression stroke. I then pulled the whole distributor and proceeded to break the other cap screw. After drilling out the old screws and retapping the screw holes, I reinstalled the distributor with the rotary button pointing to #1 plug wire on the distributor. I then snugged the distributor bolt, installed new plugs, distributor cap, rotary button and plug wires.
You've probably already guessed my next statement. The truck will not start! I tried pulling the distributor and going 3 teeth each direction. I took the TFI off the distributor and had it tested at AutoZone on a Wells tester and it checked good? I have an inline sparks light and it won't light at all. One other strange observation? The timing mark on the harmonic balancer is over 90 degrees away when the #1 piston is at TDC on a compression stroke? Does anyone out there have any suggestions?

 

Check your wiring and the stator in the distributor. Even if the timing is off, it still should have spark.

 

I've checked the wiring in the distributor. Does anyone know how to check the hall pick-up in the distributor. Also, I have double checked and the factory timing mark seems to be at 10 o'clock when number 1 piston is at TDC on a compression stroke? Can anyone explain this?

 

Be sure the wires for the coil are not broken or pulled from the plug.
I would start at the coil first, make sure all conections are good and check the coil wire. If everything is good then go into the dist.

 

If your balancer has rubber in it, I have had them slip and throw the timing marks off.

 

 

I want to start off by thanking you guys for your advice. This is the best site I have found on the net and I've been surfing around for 10 years. I'll be sure and check back periodically to see whats happening.

The good news is "the problem has been solved!

I can't explain why, but changing the PIP in the distributor cured the problem? I purchased the new one and compared the continuity readings to the old one and they were identical. (Roughly 740 ohms across the coil) It was a real job to change as I had to remove the distributor, disassemble it to change the Halls effect Pick-up device. Of course if you read the first part of my first letter you will see that the pick-up wasn't bad when I started the job? I simply removed the distributor to remove a broken distributor cap hold down screw. Anyhow, I'm back on the road again.

Thanks,

 

Problem #1: the timing marks on the timing cover ARE NOT what you time the engine by. There should be a small stamped steel pointer on the right-hand (passenger's side) of the engine, that points at the marks on the pulley.
For the no-start, find a wiring diagram. I believe that the TFI system was grounded through the dizzy, like the older Duraspark systems. Find this ground wire, and scotch-lock another wire to it. Connect this wire to the battery negative terminal.

Jared