My 2001 Monster S4 has been running great since I got it but now the fuel pump will not prime when I turn the key on. The starter spins the engine but I get no spark and the injectors are dead which I know is all tied to that fuel pump relay. I did a lot of checking and realized the ECU is not sending a ground signal to the fuel pump relay. I have a steady 12V coming into the relay but no voltage goes out to the pump, coils, or injectors. I already jumped the relay to check the pump and it primes fine and the pump also works fine on my friend's Monster. What could cause the ECU to just stop sending that ground signal to the fuel pump when the key is turned on? HELP!!!
Monster S4 will not prime the fuel pump
- Thread starter scuffkid
- Start date
blinkblink
Active member
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- Sep 4, 2025
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- 33
Have you checked if the plug is corroded or if there is a poor ground connection?
