1985 4.9 - 6cyl that seems like the computer is not advancing the timing correctly. If you adjust the timing to spec, the truck has no power and the exhaust manifold gets red hot during a test run. If I advance the timing to where the exhaust manifold doesn't turn red, the timing is so advanced that the engine doesn't want to turn over when starting. The repair manual doesn't provide enough info to troubleshoot this correctly and I need to know how the timing is controlled. A link to some detailed information concerning the timing system used would help

 

Try www.autozone.com They have free repair information and even have pictures. You need to create an account and then enter your vehicle information and search for timing gears. It goes into great detail as to the timing. The information is from alldata.

 

Just curious, did you have the SPOUT connector disconnected when adjusting the timing to 10° BTDC? If not, it needs to be disconnected prior to making timing adjustments.

 

Replaced TFI module and still same problem. Timing doesn't advance with an increase in RPM's. Supposedly, I could disconnect the SPOUT connector and the TFI module would advance timing as it feels the need, but I think the problem may be in the EEC??

 

If your timing is not steady with the SPOUT (SPark OUTput) connector disconnected, you may have a bad PIP sensor. The PIP sensor is inside the distributor under the vane cap. The PIP sensor is used to tell the TFI module the Crankshaft's position. Then the TFI tells the EEC-IV when to fire each plug.

 

Have gone thru and made sure all wiring is OK and that all connections are good. If I unplug the spout connector is the timing going to stay constant, or will it advance as the rpm's increase? Also, should I be concentrating on just the ignition side of the EEC, or can the input/output of the fuel side effect the timing thru the EEC. In other words, if everything checks out good on the ignition side back to the EEC, should I assume the EEC needs to be replaced or do I troubleshoot the fuel side also? The engine runs great, except for the fact that the ignition timing is not being advanced or retarded. PLEASE HELP, this is driving me crazy...

 

With the SPOUT connector disconnected, the timing should stay steady. The SPOUT connector has to be DISCONNECTED in order to check and adjust the initial timing. Once adjusted, the SPOUT connector is reconnected so that the EEC can receive timing infomation from the TFI module. Have you checked/replaced the PIP module as I noted above? This is the module that tells the TFI module what position the crankshaft is at in order for the EEC to fire the plug at the correct time.