Hit 20 degrees for the first time the other day and the truck would turn over but not start. Could not hear the fuel pumps come on for their 1 second when ignition on. Warmed up to 60+ and it started and ran just fine. Got cold again and same problem. Checked fuel pressure at fuel rail and zero.. either tank. Still could not hear fuel pump, either tank. Warmed up later in the day and it starts fine again. Anybody got any ideas? Similar problems? I will check voltage at the inertia switch the next time this happens and show my results. Any suggestions are appreciated.

 

Next time it doesn't start, try rocking the tank select switch rapidly (with the key OFF) to clean its contacts. If it still won't run, turn the key to RUN, pop the hood, pull the PCM PWR relay, then put it back in. Notice whether the FP relay cycles on for ~1sec.



Pull the connector off the inertia switch to check for signs of heat.

 

Got cold again today, 35, and won't start again. Checked voltage to the inertia switch on start & run. None. No fuel pressure. Jumpered the inertia switch with 12V... got full fuel pressure but still not starting. So it looks like the tank selector, fuel pumps are working just fine. Now to move back toward the PCM relay and beyond.

 

It's beginning to sound like the EEC's PC board is cracked, or something weird like that. But try the relay trick next time it won't start.

 

Problem solved... PCM relay malfunction. Actually the relay was good but apparantely at the factory (15+ years ago) the relay was installed incorrectly, bending a spade connector so that it wasn't fully in the slot. With the cold it moved enough to break the connection (+ to relay coil). Fixed the slot, replaced the relay, and now I'm good for another 15 years.