Need some help, I am really not sure what is going on with my truck, when it is cold like the first time I start it, the truck starts fine. But it will not start after it is warmed up, if you turn it over it sounds like the battery is dead, if you let it cool down a bit it starts right up. I had thought at one point that it could be a bad starter, so I went out and bought a new starter and put it on, same thing it starts fine when cold but after it is warm the engine will barely turn over, like the battery is dead.

The Truck has a new Battery, Starter, Starter Solenoid and battery cables. Most of these items were replaced because when I got the truck it did not have them. But I no long believe this is the problem with it not starting when warm. Now I believe it may have something to do with the Timing. And I really do not know how the ignition systems on this truck work. Here is what I have tried and why I believe it may be the timing.

86 Bronco 302 EFI with the TFI-IV ignition system

When cold it starts fine, after the engine is warmed up it will not start, the engine turns over like the battery is dead. If I leave the ignition off and jump the starter it turns over fine. If I turn the ignition on and jump the starter it sound like the battery is dead. If I unplug the wire that goes from the Distributor to the Ignition coil it turns over fine, and while turning it over if you plug it back it does the same thing, it turns over like the battery is going dead.

I believe all the timing on this truck is done through the PCM, which I do not know where that is at or if there is a way to test it. I know that the TFI module could be the problem and it is located on the side of the distributor. Is there a way to test any of this items or do I just need to start replacing parts? Or am I way of track and should I be looking at something else?

Any help would be greatly appreciated
Thanks
Sean

 

There is a plug that you need to unplug before monkeying with the timing it
should be right next to the coil and distributor. It is basiclly a 2 wire side by
side and they terminate in a plug with a little handle on it, unplug that and
try to start it like that when cold and see what happens, let it warm up
with the plug in and then try to start it with it in and then with it out when
it is warm.
A way to test components for heat related failure is to get a can of keyboard duster
and while holding it upside down and the truck hot and not starting, Spray the tfi
module for at least 15 seconds with the frost try starting the truck immediately.
If it starts that is your problem if not then you need toi go the say the coil it is bigger
and will need the spray time increased. Basically you want to systematically spray
and try starting every electric component until you get it to start. If it still doesn't
start you can increase the spray time and go over them again. Of course be careful
don't spray your skin, eyes etc and don't breathe in the spray!! It is just a refrigerant
I forget what number like r-155 or something You could also use a paintball tank with
a hose and a on off valve since CO2 is cheaper but the upfront cost is more but you
could use it to fill your tires etc.
I am sure you have pushed the valve on your fuel rail to see if you have fuel pressure
right? testing the actual pressure would be a good idea. Sometimes a simple electric
connector can bend and not make contact with a few degrees of heat(think x-mas
tree light flasher) All the connectors should be inspected sprayed with contact cleaner
and dielectric applied to be sure you aren't having a issue with conductivity.

 

Blue Beast, thanks I will give this a try this weekend.

also does anyone know where the PCM is located at on this truck?

Thanks

 

Follow the wires and check the ones that are on the drivers side fender for
corrosion. and then look under your dash right above the go pedal. Those two
big 10 pin connectors on the fender are prone to corrosion since they are
right where the tire spray hits and if you have rust or lots of holes in the liner
they can be pretty basty after 20 some years. Aa bit of dielectric after you
clean them will prevent it in the future.