94 2.3l 2wd XLT

Hello.
I'v been on here lately trying to get my truck to start. I had help with changing the fuel pump and then replacing the capacitors in the ECM. The help is much appreciated.

So, I got the caps changed in the ECM board, put it back in and it wouldn't start. No fuel pressure. After fooling around with this and that, I noticed that the CEL was not on when I put the ignition in On. Did i wreck the brain I asked. So I fooled around with the relays, pulled the EEC relay, looked at it, plugged it back in and heard a click from somewhere. I then remembered that I forgot to turn the ignition to Off. Looked and the CEL was on. Engine then started right up. And would start again after running a while (my initial issue).

No idea what happened. Hope that it's all good now, but am waiting for the shoe to drop. Any ideas?

 

If the CEL came on, what code(s) is the computer throwing out?

 

Not uncommon at all to have systems start to work again after unplugging and plugging back in connectors, like relays

Anytime you have "sensor" issues you should first unplug and then plug back in connectors for that sensor, that often fixes the issue, this is why "new" sensor can fix a problem, because old sensor was unplugged to install new sensor

When electricity passes between the two metal contacts it will build up a layer of "corrosion", when you unplug, separate the metal pieces, and the plug them back together you scrap off that layer and get a good connection back

 

This is usually a result of a poor connection to begin with. A good connection, both mechanically and electrically, will not create corrosion. Any such corrosion will be due to some external action, such as being in a corrosive atmosphere or water infiltration.

When contacts are close together, electrical current will arc between them. The two common results are 1. pitting of the surface and 2. building of carbon. The former turns the original smooth surfaces of the contacts into a rough and uneven texture, much like arc welding (which is essentially what it is). In some cases, the pitting is so severe the contacts weld themselves together and can no longer open the circuit. The latter will add a small layer of black, chalky carbon to the surrounding area. On some occasions, this buildup can actually catch fire and create a large flash.

 

+1 ^^^

Except for galvanic corrosion, most Ford connections will be the same type of metal, relays or sensors may have a different metal, different manufacturer, so over time this can get a corrosion layer, assuming a non-air tight connection which most are

But point was unplug it and plug it back in just because its a good idea and its FREE to do :)

 

I am assuming that the relay for the ECM is used instead of a fuse?

 

The ECM(PCM) Relay has a fuse on the 12volt wire it uses to power up devices with key on, these include the ECM, of course, but also a few relays, all solenoids in engine bay, fuel injectors and IAC Valve

 

If I had only known that about the relay to the ECM, that would be where I would have started. But, as it is, by trying to find out why the engine would not start after running a while, I changed the fuel pump. While the bed was off for that, the differential got new seals and it was easier to service the drum brakes. And the ECM got new caps. I'm glad the thing is running ok now.......so far.