Before I forget, there is a common problem you should be aware of if you have a steel gas tank. The pump is grounded through it to the straps, then to the frame. If the tank gets rusty, that ground can be lost. You'll have that 12 volts on the feed wire, but a faster way to check for this problem is to use a simple test light. Ground it to a good, paint and rust-free point on the body, then place the probe right on the tank. If the test light turns on dimly, drill a small hole in the tank's flange, outside of the weld, then run a screw in there and attach a wire to it and to the frame.
At the pump's connector, you should have been testing on the gray wire for 12 volts. You should normally see 12 volts for one or two seconds after turning on the ignition switch, then again when you're cranking the engine. If you DO see 12 volts for the first couple of seconds, we know the relay and wiring are okay, and the Engine Computer has control of that relay.
If you don't see that initial 12 volts, we're going to have to test at the relay. Either you're going to have to gain access to the underside of the fuse / relay block, or you must find a way to test on the relay's terminals while it's still plugged in. You might be able to lift the relay just enough so you can poke the test light's probe in there, or you can insert little pieces of wire to use as test points. You have to be careful though to not put enough pressure on the terminals in the socket that they become stretched. That will cause them to make intermittent contact.
To start with, you can remove the relay completely, then test at each terminal with the test light. There should be one with 12 volts all the time. If you're doing this underneath, that will be on the orange wire.
Next, move the test light's ground clip to the battery's positive post so we can test for grounds. Probe the remaining three terminals in the relay socket. One will make a bright test light. That's the ground wire for the relay and is black. Now look for a second terminal like that. That is a green / white wire. The test light should light up but it will be relatively dim because you're also reading to ground through the pump motor.
If those three circuits are okay, we have to determine why the computer isn't turning the relay on.
Tuesday, June 16th, 2015 AT 5:08 PM