kmpconley

Well either way, it's the only slot on the wire harness that lights up the test light. It's very dim but it lights up. When I checked the relay and inertia switch, the light lit up very bright. But when I checked the positive power wire slot on the harness nothing lit up.

DPDISXR4Ti

Keep in mind, it's the EEC Relay powering the PCM that is responsible for that 2-second priming when you first turn the ignition key "on". I've seen more of those fail than the fuel pump relay per se. Obviously both need to be operational - I always carry spares.

kmpconley

So there is a EEC relay somewhere? Cuz like I said in prior posts, I've checked all the relays an that are good. I've also had someone tell me that this is a computer problem because the wire harness isn't "hot" when I tested it because the computer tells it when it gets electricity to turn on the pump. It doesn't always have current running to it.

DPDISXR4Ti

Yes, there is a separate EEC Relay. On a '91 it's one of those ganged relays mounted to the driver side inner fender/splash shield.

A failing PCM could also prevent the fuel pump from energizing, and in fact, it is very common for them to fail. Do a search on "leaking PCM capacitor" and you'll get lots to read.

kmpconley

Where is the ECM located on the truck. I'm lookin through my book and can't find it. If it is leaking, I'm not big into electronics so I'm not fixing any of that ****, I'm just gonna buy the new ECM and install it.

DPDISXR4Ti

It's located at the driver-side firewall - you'll see the harness going to a ~4" connector, fastened with a single 10mm-headed bolt. It's easy enough to loosen and remove the connector, but there's not enough clearance to remove the PCM unless you remove the plastic splash shield (i.e. inner fender).

On the earlier (pre '92) trucks you can remove the PCM from inside the cabin, but it's a much bigger project to do so on the later vehicle - easier to remove the shield. You can probably get away with just a partial removal - I know at the junkyard I'm able to just pry the shield out of the way after removing one screw, but scratching/bending the fender isn't so much a concern there.