DGorvetzian
Recruit
- Joined
- Jul 15, 2020
- Messages
- 2
I have a Mercury Force 40 HP EFI engine on my pontoon. Whether in neutral or in gear, once the tach hits about 2000 RPM, I get a continuous horn until I bring it back to neutral. I've consulted my service manual, as well as MercMarine Outboard Customer Assistance; both indicate that a continuous horn can only be triggered by:
- Engine overheat
- Low oil pressure
- Voltage <10v or >16V
- Coolant sensor failure
- Excessive RPM
I know it's not overheat; this happens right when it's started, and I expect a faulty sensor wouldn't be speed-sensitive.
Oil is full, and oil indicator on tach isn't lit when this happens. Also, I expect the fault would show at / under 2000 RPM.
Voltage reads normal at the battery with a multi-meter.
Tach reads normal, and if it were a faulty sensor, I expect the same sensor drives the tach.
We are guessing this is a fuel problem, and we're awaiting an opportunity to check the fuel pressure once my mechanic gets his gauge back that he loaned out. This would make sense, as if I open the air intake hose on the manifold, presumingly creating a lean condition, the horn sounds instantly. But that's weird, because Mercury *swears* that a lean condition wouldn't sound the horn.
Has anyone run in to this before?
/Doug
- Engine overheat
- Low oil pressure
- Voltage <10v or >16V
- Coolant sensor failure
- Excessive RPM
I know it's not overheat; this happens right when it's started, and I expect a faulty sensor wouldn't be speed-sensitive.
Oil is full, and oil indicator on tach isn't lit when this happens. Also, I expect the fault would show at / under 2000 RPM.
Voltage reads normal at the battery with a multi-meter.
Tach reads normal, and if it were a faulty sensor, I expect the same sensor drives the tach.
We are guessing this is a fuel problem, and we're awaiting an opportunity to check the fuel pressure once my mechanic gets his gauge back that he loaned out. This would make sense, as if I open the air intake hose on the manifold, presumingly creating a lean condition, the horn sounds instantly. But that's weird, because Mercury *swears* that a lean condition wouldn't sound the horn.
Has anyone run in to this before?
/Doug