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Title: No ground signal from ECU to fuel pump relay Post by: 2.0 on October 12, 2023, 05:32:31 AM 2001 Monster S4
5K Miles I’m the second owner of this bike which has been running well with no issues up until now. After nothing out of the ordinary, the fuel pump failed to prime, starter would run, but not turn over the engine. The spark plugs are also not sparking, injectors—nope. I do understand this is all downstream of the fuel pump relay. After a bunch of troubleshooting, I’ve come to realize I’m not receiving a ground signal from the ECU when the key is switched to position ON. I have 12V+ steady from 3 terminals (Two hot in, and the Br/Bk from the ECU. No voltage to the Br/W terminal (to fuel pump, Coils, and injectors) Any ideas on what the ECU wouldn’t be sending a ground signal to the fuel pump to prime when I turn the key to on? Thanks in advance EDIT: I forgot to mention I’ve ran jumper wires across the relay to check the pump. It primes this way. I’ve also hooked my fuel pump up to my boss’ monster, and it primes this way as well. Let me know if any additional context would help you Title: Re: No ground signal from ECU to fuel pump relay Post by: 2.0 on October 18, 2023, 07:09:03 AM After much deliberation, I’ve concluded the ECU’s internal ground is fried. New one on the way.
Title: Re: No ground signal from ECU to fuel pump relay Post by: stopintime on October 18, 2023, 09:13:31 AM Good work [thumbsup] thanks for the update.
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