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97 Jeep 96 Dodge Ram
8 Posts
If the fuel pump relay takes control of the fuel pump during start up only, what takes over after the engine is running and the relay shuts down?

The fuel pump relay does not function only during start up. It functions whenever the engine is running. When you turn the key to on, the ECM gounds the control circuit for the FP relay. This activates the relay and the pump runs for a couple of seconds. You should hear the pump run when near the fuel tank. This brief run time primes the fuel system ready for starting. The ECM turns off the relay if no start action is taken.

When you turn key to start, the ECM checks all the sensor info and turns the relay on for engine running operation. The relay is on when the engine is running. The relay feeds electrical power to the fuel sender and fuel pump motor.

What the dealer did is use a short jumper to jump pin 30 and 87 to get power to the pump for troubleshooting.

I would think that KIA would do some kind of incline test to see if the engine runs while on hilly terrain. Not sure I believe what they said. If true, there should be some warning in the owner's manual.

You may want to change the FP relay in case it may be going bad. Next time you have a no start problem check to see if you are getting a spark. Most no start problems is either spark or fuel related. There are a few sensors that relate to these 2 systems. If you have spark you can concentrate on fuel.
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