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The fuel injection computer sends an "on" signal to the pump relay for about 1 second when you turn the key to the start position. The purpose is to pressurize the fuel system so that the engine can have enough fuel to start. After the engine starts the computer receives signals from the crankshaft position/rotation sensor that tell it the engine is running, and then turns the relay "on" again. If the computer loses the "engine running" signal from the crankshaft sensor, then it cuts off the fuel pump relay. It is for safety: If you are in a severe wreck you don't want the fuel pump running if the fuel lines are damaged, so the computer shuts it off if the engine is stopped for any reason.
If your pumps are not running when you first try to start the car, then I would suspect that the circuits in the fuel computer that supply the signal to run the relay have failed. There is an entry in the FAQ about that. You can build the little add on circuit that is shown, and that will work. I did and it worked for about a year. But eventually either the rest of the computer failed or a wire from my add on circuit touched something it shouldn't have and caused a failure. I would suggest checking to see if the computer is energizing the relay when you try to start the car. If not then the computer is probably bad. There are diagrams for the computer wiring in the FAQ, I think. You want to check the wire that runs the pump relay to see what it does when you turn the key to the "On" or KP II position after the car has been sitting for an hour or so. Based on my experience, I would recommend just buying a replacement computer if the computer is the problem.
If the computer is running the pump for a second or so, but won't let the pump run when the car starts, then it is more likely the crank position sensor that is not letting the computer know that the engine is running.
If you need a computer, search on eBay for a seller named 240salvage, and contact him. He is rhaire from the Brickboard and is a very trusted and reliable source. Very reasonable prices and knowledgable too.
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Scott Cook - 1991 745T, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)
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