Weird Fuel Issue
05-04-23, 10:56 PM
#1
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Weird Fuel Issue
Having an issue with the Rx-7. It is able to start but does not stay running unless I ground the 1K pin at the ECU. As soon as I unground that pin, the car dies.
I have done the following Fuel pump mod as shown by sonicgroove:
https://www.rx7club.com/3rd-generati...ewire-1124167/
The car seems to sputter and hesitate in the 3-6k rpm range but just cant figure out if its a fuel issue or a different issue entirely. Please let me know if there is any more information I can offer.
I have done the following Fuel pump mod as shown by sonicgroove:
https://www.rx7club.com/3rd-generati...ewire-1124167/
The car seems to sputter and hesitate in the 3-6k rpm range but just cant figure out if its a fuel issue or a different issue entirely. Please let me know if there is any more information I can offer.
05-05-23, 09:13 AM
#2
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What is the 1k pin on the ECU?
Was it working properly before you did the rewire mod?
Dale
Was it working properly before you did the rewire mod?
Dale
05-05-23, 12:20 PM
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i think this would be the best way to describe it without me confusing you.
Before the fuel pump rewire it was the same, the car starts but 1K does not ground which then tells the car to shut off. But if I ground the pin, the car starts and stays running.
Originally, I figured the fuel pump rewire mod would help solve the issue. But it did not.
Last edited by simronrx7; 05-05-23 at 01:20 PM.
05-05-23, 02:15 PM
#4
Pin 1K from the ECU controls the fuel pump speed relay. When pin 1k is off (not connecting the relay coil to ground), the fuel pump gets all of its power through the fuel pump resistor so it will run at low speed. Using a multimeter you should measure about 12V at one side of the fuel pump resistor (located near the brake booster on the LHD cars) and between 6V - 9V at the other side of the fuel pump resistor (assuming the pump is connected and drawing power). If the fuel pump resistor is disconnected, there won't be any power going to the fuel pump so it won't run at all. At idle and light-load cruise, that 6V-9V with the OEM resistor should be plenty of fuel flow for the engine to run without stalling. At higher RPM or higher load, the speed relay activates to basically bypass the fuel pump resistor and provide full 12V power to the pump.
Last edited by scotty305; 05-05-23 at 03:05 PM.
05-06-23, 02:41 PM
#5
RX-7 Bad Ass
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Yeah it's gonna be something with the fuel pump resistor most likely, either missing or unplugged. I don't know of one ever going bad, they are just a giant heavy duty resistor, no moving parts or anything to really fail.
Dale
Dale
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