I have a 1994 4x4 F150 E40D and for about 6 months now every time after it rains my truck will run fine on first start up for about 15 seconds then check engine light comes on, runs very rich/rough, absolutley no power when i put it in Drive (have to drop in 2nd to take off from a stop) also i cannot turn overdrive off and fuel pump constantly runs KOEO all this is only when its messing up. I have tried everything. Pulled ECM out opened it up let both ECM and plug dry for at least 2 hours, pulled distributor cap off and let dry, tried resetting the ECM but int never fails that everytime it rains it messes up then after a day or two of dry weather it runs with no problems. Does anybody have any idea what could be getting wet and causing this?

 

When was the last time the cap rotor and wires replaced?

also check the coil and ignition modual.

good luk

 

This is a classic sign of a bad ignition coil but since the fuel pump is running constantly the ECM could be failing as well.

 

But it only does it when it rains so if either were going bad dont you think itd do it all the time?

 

Wires- Probably 5 months ago

cap and rotor- to the best of my knowledge, never..

How do i check coil and ignition modual and where are they located?

 

I would replace the cap rotor and coil first, make sure you put dialectric grease on both ends of the plug wires

once it dries out get a spray bottle of water adjust to a fine mist and start spraying around the engine bay at the likely sources of the problem with the engine running ,

doubely make sure all your plug wires are seated and greased properly!

good luck