2000 7.4l MEP intermittent alarm

[Locke]

I have a 2000 Sea Ray 270 Sundancer w/ a 7.4L the engine serial is 0L621950.
I just put the boat back in the water after having the transom seal replaced, it runs fine but when I raise the RPM's up to get up on plane the alarm system starts a pulsing alarm that will not stop until I shut off the engine. Turn the engine back on and once again all is good until I raise the RPM's. I disconnected the drive oil sender and no change, the oil pressure and water temp gauges show normal. The owners manual doesn't tell me what a pulse alarm means just that a solid alarm signals trouble. Any ideas what to check? I would rather fix it myself than take it back out of the lake if possible.

Locke

 

[alldodge]

You have a MEFI3 module and there can be a few things. My first thought would be the engine is sensing a knock but could be something else. Need to read the codes to determine what is happening.

You can buy one premade, just search Mercruiser Multifunction Indicator Lamp or make one with a paper clip and a 12V resistor type LED


To use, connect as shown the turn ignition to ON do not start. The light will start flashing. A code 12 is all is good (flash, pause, flash, flash)

 

[MarkSee]

My engine is in the same serial number range (that I see referred to as MPI) and have not experienced that condition but curious that if the throttle is in the fast-neutral position and you raise the rpm, do you get the same alarm or is the alarm only when under load?

Mark

 

[Locke]

I've run it up to 3600 RPM in neutral for a few seconds and haven't gotten the alarm.
I was back out yesterday and tried a few more things:
I slowly advanced the throttle and when I got to 3000 the alarm started.
I quickly advanced the throttle to 3600 to get up on plane and the alarm sound after about 10 seconds.
I have a mechanic scheduled next week to plug in a tool and read the ECM, maybe this will give some answers.

Locke

 

[alldodge]

Sounds like a plan, I'm sure there is a code

 

[Locke]

Well I'm having a little trouble getting a mechanic to read the codes so I'm going to try the home made code reader route. I'm assuming that if all goes well when I'll get a series of flashes that correspond to trouble codes. Where do I find a list that interprets the flashes? The only one I'm aware of is, flash-pause-flash-flash, which tells me the diagnostics are working.

Locke

 

[Locke]

Maybe I'm making this harder than it should be. If the flash-pause-flash-flash is for code 12 I'll assume that flash-pause-flash-flash-flash-flash is code 14 showing an engine coolant temperature issue. I have the codes that are in the Fuel System Trouble section.

Locke

 

[Locke]

I used the led/paper clip code reader and it worked great, came up with a 44 code which spears to be a knock sensor problem. This motor has 2 sensors but only one is connected. Now I'm trying to find the knock sensor module, any hints on where it is located?

Locke

 

[alldodge]

Sorry it's taking me so long to get back with, been out of town.

Code 44 means the ECM is not detecting the knock sensor. It does this one time with each restart of the motor. When you first start throttling up it retards the timing until it senses a knock from the sensor. If no knock is sensed then it will set a code and retard the timing by about 3 degrees. The boat still preforms, just not as well.

Code 44 can be caused by a bad connection on the knock sensor, and bad sensor or a bad connection/wire going to the ECM. Find the solid bark Blue wire and run continuity back to the ECM. If all checks out get another sensor. I replaced mine from Rock Auto, pretty cheap

Edit: BTW here are the codes for your MEFI 3

 

[Locke]

I checked the connection back to the ECM with an ohm meter and its good. I replaced the sensor ran the boat and got the same alarm. On this motor it appears the knock sensor is internal to the ECM so I'm not sure what else can be the problem other than the ECM. I've never cleared out the codes I assume that's not it.

Locke

Locke

 

[alldodge]

This motor has 2 sensors but only one is connected.

Locke

Your correct the MEFI 3 has the knock sensor built into the ECM. If your ECM is set up for two knock sensors and only one is connected you will get the same error. Note L29 engine is the only one which used two sensors. What is the part number on your ECM?

 

[Locke]

There are 2 numbers on the back of the ECM

16237009
867009KA00046227

 

[alldodge]

The 16237009 is the Delphi number and it is a MEFI3, the other I'm in the process of trying to find it. You checked continuity, replaced the knock sensor, will continue to look around.

You need to clear the code

1. Install LED
2. Turn ignition to ON but do not start
3. Connect A and B with paper clip
4. Move the throttle from closed to wide-open and back to closed.
5. Turn the ignition key OFF for at least 20 seconds.
6. Remove paper clip
7. Turn ignition ON but do not start
8. Connect paper clip
9. See if code has cleared and flashes for 12 show up

Wonder if Fun Times can find out something on the ECM?

 

[Fun Times]

The long number 867009KA00046227 is basically a bar coded part numbers for factory use and won't be much help. I recall the Merc tech support guys/team having a special internal "list" that they could look up in order to see exactly what type of tuning/fuel/timing/etc. mapping the ECM has so that number may have played a part in it. The shorter number give us the basic info to help let us know it truly is a MEFI 3. http://www.pirate4x4.com/tech/billavista/MEFI/

If one of the blue wires on either side of the engine are disconnected from one of the two knock sensors than yes that could trigger the alarm. I recall reading more than once on these boating forums that members had finally found where one of the sensor wires where found to be either simply disconnected during a service, the wire plug connecter broken or the blue wire is burned or chafed where it's hard to find somewhere between the sensor and ECM. Your next goal needs to be finding that other wire that's not connected to the knock sensor.

 

[alldodge]

Was wondering FT if his ECM is setup for the L29 (or even has a L29 Gen VI block), if it is then he does need two knock sensors, if not then he needs only one. Any way to find out? So far I'm coming up empty

 

[Locke]

Well lucky for me the easy (cheap) solution solved my problem. I contorted myself down into the bilge and found the connector wire for the starboard side knock sensor, plugged it in took the boat out and no alarm.
The sensor must have been pulled off when the engine was moved during the transom seal replacement.
I'm just happy I didn't have to pay a mechanic $$$$ to figure this out. Thank you all for your help.

Locke

 

[alldodge]

Way cool Locke, glad it was an easy fix, bet ya wish it was a bit shorter one

While your thinking about it, how about going to your signature and adding something like "MEFI 3 L29"

This way if there are other questions later (hope not) but it will give us some more info when were looking. Have a great boating day

 

[Fun Times]

Was wondering FT if his ECM is setup for the L29 (or even has a L29 Gen VI block), if it is then he does need two knock sensors, if not then he needs only one. Any way to find out? So far I'm coming up empty

Yes using his serial number in post number 1 shows he has the L29 engine,

PARTS CATALOGS

• 809994 98 - 7.4L MPI Bravo L29 (GEN VI)

In the end of this one AD, nice job as you guided Locke to a thoroughly tested completion.:thumb:

Well lucky for me the easy (cheap) solution solved my problem. I contorted myself down into the bulge and found the connector wire for the starboard side knock sensor, plugged it in took the boat out and no alarm.
The sensor must have been pulled off when the engine was moved during the transom seal replacement.
I'm just happy I didn't have to pay a mechanic $$$$ to figure this out. Thank you all for your help.

Locke

After the service of removing the engine etc., it's usually something like that....Glad you found it.:encouragement:

It would be in your best interest to take some time and carefully inspect, lightly touch/wiggle as many items on the engine to ensure they seem installed properly and tightened down including all wiring going to the engine. Sometimes things get missed depending on who is doing the work and that varies between individuals.

 

[alldodge]

Yes using his serial number in post number 1 shows he has the L29 engine,

PARTS CATALOGS

• 809994 98 - 7.4L MPI Bravo L29 (GEN VI)

I'm almost ready to throw in the towel in looking things up. I look up a serial number on the Merc site and someone will come along and tell me that Merc is not up to date and to use Mercruiserparts. Then I use Mercruiserparts and I'm told that I should use the Merc site because there is no clear info link for what I'm looking for. So Merc site shows L29 in this occurrence but the next will show a list and will not be up to date.

Guess I'll be linking you in more often or maybe just make sure you look at it first.