Right off the bat I see the pump is grounded and the other wire gets 12 volts to turn it on, just like all the other cars I'm familiar with. There is a fuel pump relay. It's part of a "relay set" shown on the bottom of page 9. It appears current for the pump comes from pin 34 of the control module, (top right corner), and through a fuse feeding the relay, but they don't say which one.
After following this around for a while, it looks almost exactly like the automatic shutdown (ASD) relay circuit Chrysler has been using since the mid '80s. What I can't tell, however, is how the circuit works or what each terminal is for on the control module. That relay set has two relays inside it, one for the fuel pump and one for the injectors and other stuff, just like on Chryslers. Both relays are turned on by grounding a common wire, (circuit 85 / pin 28 of the module), just like on Chryslers.
Now I'm going to go out on a limb and make some educated guesses. The control module turns the fuel pump relay on, I think when it gets pulses from the distributor. The module grounds one side of the relay's coil. !2 volts feeds the other side of the coil from an inline fuse.
Now that the relay is turning on, it switches on the high-current 12 volts to power the pump motor. THAT 12 volts comes from the air flow sensor. That is shown as a switch too. My guess is:
1) There has to be air flow, meaning you're cranking the engine, to get the 12 volts up to the relay set.
2) The fuel pump relay needs 12 volts from the inline fuse, and
3) it needs to be grounded by the module when that sees pulses from the distributor.
If the fuel line is ruptured in a crash, the engine can't run without fuel pressure, so it stalls. There's no pulses from the distributor, so the module turns the fuel pump and injector relays off. Even if the fuel pump relay sticks on or is bypassed, there won't be any 12 volts to switch on to the pump when there's no air flowing through the air flow sensor. You have two things turning the pump off.
Check that inline fuse, and check the fresh air tube between the air flow sensor and the throttle body. If you have that removed, the sensor won't see any air flow and the pump will stop running.
Thursday, September 4th, 2014 AT 8:21 PM