northeast_bass_guy
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- Oct 12, 2026
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Engine: 2019 Mercury 40 ELPT FourStroke EFI, serial 1C567275. Console steer with remote control, power trim.
Symptoms:
- Cranks normally, never fires. Ran 3 weeks ago on a weeklong trip.
- It used to beep and make a click/clunk under the cowl when I turned the key on. Now there is no beep, no click, and I can't hear the fuel pump prime.
- Engine ran fine about a month ago. Freshly charged battery (13 V), and it was just serviced for the season (didn't start before or after servicing).
What I've checked:
- All engine fuses intact. Stop switch/lanyard in run position.
- Unplugged the round remote control plug at the engine. On the engine-side half, pin A (red) has constant 12 V, and pin C is the purple wire.
- Jumping A to C (fused jumper) puts 12 V on C, but nothing happens: no beep, click or pump hum.
- Cleaned and reseated the round plug. After that, with everything plugged in, the purple wire at the ECM connector reads 12 V with the key on and 0 V with the key off, under load. So the key circuit seems fine.
- At the ECM connector (harness half, ECM unplugged) I believe the constant feed, key-switched feed and grounds all read good. The black wires I tested read about 12 V with the red lead on battery positive.
- Reseated the ECM plug. No change.
- I can't find a separate relay under the cowl.
I ordered a SmartCraft Connect Mobile module to see if the ECM talks to the Mercury Marine app, and I may take it to a dealer for diagnostics.
Questions:
1. Has anyone seen this on a 3-cylinder 40 EFI, where the key circuit is good, power and grounds are good at the ECM, and it still won't wake?
2. Is there a main relay on this engine, and where? Or does the ECM handle that internally?
3. Where does the key-on beep come from on a console rig: the ECM, or the control box/key harness?
4. If it is the ECM, is there anything I should check before replacing it, like the fuel pump connection or draw, so I don't kill a new one?
Happy to post photos of the ECM connector and the cap if that helps. Thanks.
Symptoms:
- Cranks normally, never fires. Ran 3 weeks ago on a weeklong trip.
- It used to beep and make a click/clunk under the cowl when I turned the key on. Now there is no beep, no click, and I can't hear the fuel pump prime.
- Engine ran fine about a month ago. Freshly charged battery (13 V), and it was just serviced for the season (didn't start before or after servicing).
What I've checked:
- All engine fuses intact. Stop switch/lanyard in run position.
- Unplugged the round remote control plug at the engine. On the engine-side half, pin A (red) has constant 12 V, and pin C is the purple wire.
- Jumping A to C (fused jumper) puts 12 V on C, but nothing happens: no beep, click or pump hum.
- Cleaned and reseated the round plug. After that, with everything plugged in, the purple wire at the ECM connector reads 12 V with the key on and 0 V with the key off, under load. So the key circuit seems fine.
- At the ECM connector (harness half, ECM unplugged) I believe the constant feed, key-switched feed and grounds all read good. The black wires I tested read about 12 V with the red lead on battery positive.
- Reseated the ECM plug. No change.
- I can't find a separate relay under the cowl.
I ordered a SmartCraft Connect Mobile module to see if the ECM talks to the Mercury Marine app, and I may take it to a dealer for diagnostics.
Questions:
1. Has anyone seen this on a 3-cylinder 40 EFI, where the key circuit is good, power and grounds are good at the ECM, and it still won't wake?
2. Is there a main relay on this engine, and where? Or does the ECM handle that internally?
3. Where does the key-on beep come from on a console rig: the ECM, or the control box/key harness?
4. If it is the ECM, is there anything I should check before replacing it, like the fuel pump connection or draw, so I don't kill a new one?
Happy to post photos of the ECM connector and the cap if that helps. Thanks.
