Carver 404-Engine Alarm Merc 7.4

[RReardon]

Hi Fellow Carver Owners

I hope every one is having a great boating season. I have a 2000 Carver 404, twin Merc 7.4 gas engines. This is what I have been experiencing the last few runs with it:

* I start crusing and get up to around 11 Knots (maybe 3000rpm) and I get what I believe to be the engine alarm
* It use to happen very infrequently, but now happens more often
* If I shut the port engine down and restart it goes away, but will come back after awhile.
* All of the gauges look fine (oil pressure, water temp, et)
* The engine itself sounds and preforms weill

In the manual, it says the engine alarm monitors oil pressure and coolant temp. Both gauges are fine and I check and keep the oil filled.
A few questions:
* Any ideas on other things that set an engine alarm off?
* Can other instruments, such a fuel computer be wired into that alarm and then set it off (I don't trust my fuel computer)
* Is there any way to shut the alar off

Calling the mechanic this week, Was just curious if anyone had any thougths?

Thanks
Rich

[bud37]

To help the guys , what kind of alarm are you getting, solid beep, two beeps frequently, sound like the beeps when you turn the key to start ?? or is it possible your engine room fume alarm is going off ?

[Viper]

I suspect that if it were the fume detector alarm, it would continue after the engine was shut down. I'm thinking this is 7.4 MPI? If that's the case and you've confirmed it's an engine alarm and not something else, you shut the alarm off by diagnosing what's causing the alarm and remedying that. Hooking up to a diagnostic tool will let you know what codes are active during the alarm and set you in the right direction.

Can you post an engine serial number?

[RReardon]

Good Morning Viper and Bud

Thank you for the responses. The alarm sounds like the alarm that cycles when I initially turn the engines to start them up. It is a single, steady beep, maybe 1-2 seconds apart and lasting maybe 1 second.

The serial numbers are:
Port - OL395637
Starboard- OL395638

Do you know if each engine has its own alarm and if they do, do you think its fair to say the issue is located in the port engine, since shutting that one down shuts the alarm off (if I shut only the starboard down, the alarm continues to cycle).

Any additional thoughts are great.

Thanks
Rich

[bud37]

Each engine has its own management system ( ecm, probably MEFI 3 for yours) with its own alarms......your tech will have to connect to troubleshoot as Viper says...here is something I have, maybe help a bit..its a start.

The MEFI-3 engine’s Audio Warning system will sound the alarm differently and it has more items that will cause it to sound.
There is what is called a ‘soft’ and a ‘hard’ alarm.
1. SoftAlarm=Below3000rpm.Hornonfor1second,offfor3seconds,onfor1second, off for 3 seconds, etc.
2. Hard Alarm = Above 3000 rpm. Horn sounds all the time.
Audio alarm sounds for the same malfunctions as MEFI-1 and -2;
1. YMCM-LowlubelevelinGearLubeBottle.[General1]orMIE-HighTransmissionfluid temperature [General 2].
2. MCM/MIE-Lowengineoilpressure.
3. MCM/MIE - Too high engine coolant temperature.
YEarly production and service ECMs had the following items that will sound the alarm;
1. MCM/MIE–HornwillsoundifthereisanactiveengineDiagnosticTroubleCode[DTC] that is occurring while the engine is running. The horn will not sound a stored DTC. Correcting the DTC malfunction will stop the horn.
2. MCM/MIE–HornwillsoundifthebatteryvoltagetotheECMislow,[lessthan9vforat least 5 seconds]. Using the throttle lever to increase engine rpm to get the alternator to put out more voltage will correct most low voltage problems.
3. MCM/MIE – V6 and V8 305/350 cid engines only. Horn will sound if there is low fuel pressure [for at least 5 seconds]. These engines have a fuel pressure sensor. The EFI engines have the sensor in the throttle body unit and the MPI engines have the sensor located in the port fuel rail toward the rear of the engine. Correcting the cause of the low fuel pressure will stop the horn.
YThe ECM checksums listed below have these additional alarms turned ON in them.
NOTE: Later production and service replacement ECMs have these extra alarms turned off. If the ECM checksum is different from the ones listed below, the extra alarms in that ECM is turned OFF.
MCM 4.3L EFI: ECM never had these extra alarms turned on.
MCM 5.0L EFI: With D04B or D074 checksum.
MCM 5.7L EFI: With D7ED or D798 checksum.
MCM 350 MPI, MCM 350 MPI Horizon, MIE 350 MPI Ski, MIE 350 MPI Inboard or MIE 350 MPI Horizon Inboard: With E60D or EAED checksum.
MIE Black Scorpion: With BB98 or BB42 checksum.
MCM 7.4L MPI or MIE 7.4L MPI Inboard: With FE28.checksum.
MCM 454 MPI, MCM 454 MPI Horizon or MIE 454 MPI Horizon Inboard: With EBC4 check- sum.
MCM 502 MPI or MIE 8.2L MPI Inboard: With F02D checksum.

[tomschauer]

I am pretty certain the transmission high temp will also sound the alarm.

[Viper]

I agree with all the above.

I checked the serial number and nothing really stands out. Bud37 listed a good breakdown of alarms. Pretty sure all but about 3 of them won't apply to your application so don't stress if you can't find them but it's a good reference to start from. You're likely looking at low oil, high water temp or low voltage that's setting the alarm. Check your batteries and alternator output. The ECMs don't like low voltage.

Source of the post...... Can other instruments, such a fuel computer be wired into that alarm and then set it off (I don't trust my fuel computer)

What do you mean by this? An aftermarket fuel flow monitor?

[Dewmyster]

The alarm I experinced was a port tranmission over heat alarm, which stopped when I finally turned the engine off, followed by 3 weeks of down time and an expensive rebuild. Be very careful.

[RReardon]

Thanks Tom/Bud/Viper

This has been really helpful. They are running the diagnostic tomorrow, so I should know a lot more then, It would be interesting if it were low oil pressure, only in that I watch my gauges pretty closely and they always seem to be mid point to slightly above. The coolant also always stays around midpoint.

The electrical output is a good one and I cant say for sure as I don't watch my voltmeters all that much during cruising (assuming that is where it would show up in that that bad alternator would let the battery run down).

The reason I asked about the fuel computer is that it is aftermarket and I have not been able to make head nor tail of how to use it, program it or anything else (not real user friendly). I just though if there was an alarm on that (low fuel, etc), that if it was wired into the engine alarm maybe it could be an aftermarket device like that......maybe reaching.

Since I have access to all this great knowledge, I have kind of a dumb question. I checked the transmission fluid, but didn't do it hot, so that was useless at the time. However, is there a separate "gear lube" dipstick somewhere that I should be checking. The Merc manual discusses transmission fluid, but I have seen nothing about gear lube. Was just curious.

Thanks again for all the great info.

Rich

[Viper]

No gear lube monitoring in your case. That is for sterndrive applications.