Engine alarm help

[BIGALF]

Re: Engine alarm help

will do that as last resort.

 

[BIGALF]

Re: Engine alarm help

My service guy just tried the scanner in the shop to read the codes. However, he said there were no codes saved. Is this because I turned off the battery after I took the boat out of the water?

 

[dubs283]

Re: Engine alarm help

My service guy just tried the scanner in the shop to read the codes. However, he said there were no codes saved. Is this because I turned off the battery after I took the boat out of the water?

no

the MEFI system does not save all codes, in that when an "event" happens, sometimes the only way to see the fault code is to have the scanner attached while the alarm is sounding

do what fun times suggested and disconnect the switch wires at various senders while the alarm is sounding, when the alarm stops thats the sender causing the issue. don't worry about losing data as none is saved anyways

also, i don't believe the MEFI system has a guardian mode that reduces RPM in the event of an engine sensor fault - that is being caused by something else, just for fun, when was the last FULL tune-up including fuel filters??

 

[BIGALF]

Re: Engine alarm help

Thanks for the response. I'll try the boat again Friday, 80 and sunny here so I think the weather is good. I put in new plugs 18 months ago. I did not change fuel filter or fuel /water separator in awhile. I don't know what system exactly I have but the engine does go on guardian mode and alarm goes off at the same time. After I turn the engine off and then turn it on again it works fine for the rest of the days run.

 

[cdiamond]

Re: Engine alarm help

FYI

the 'senders' that operate gauges showing oil pressure, engine temp, etc.... might show normal readings

there are however additional and completely separate 'sensors' on all efi systems - engine coolant temp, water pressure etc....

that the computer (ECM) reads

if one of these sensors sends a reading to the ecm - that indicates a condition which may cause engine damage

the ecm WILL reduce power

the newer systems call it 'guardian'

the older systems called it 'power reduction'

point being - ALL marine efi systems by mercruiser had engine protection

the ONLY way to determine which sensor is perhaps sending an incorrect signal

is a SCANNER

pulling wires off sensors WILL NOT DIAGNOSE ANYTHING

it will only tell the ecm of additional problems

 

[alldodge]

Re: Engine alarm help

pulling wires off sensors WILL NOT DIAGNOSE ANYTHING

Let see, if the alarm is sounding and by pulling the wire off the sender the alarm stops, this would not diagnose the problem, must be a rocket science thing because it would tell this old guy something.

 

[cdiamond]

Re: Engine alarm help

well from one old guy to another

maybe you need to learn the difference between a sender and a sensor

two completely different things

pulling the right wire off the right sender could silence an alarm

pulling ANY wire(s) off a sensor will - again - only tell the ecm there is another problem

 

[Fun Times]

Re: Engine alarm help

there are however additional and completely separate 'sensors' on all efi systems - engine coolant temp, water pressure etc....

that the computer (ECM) reads

if one of these sensors sends a reading to the ecm - that indicates a condition which may cause engine damage

the ecm WILL reduce power.

the newer systems call it 'guardian'

the older systems called it 'power reduction'

point being - ALL marine efi systems by mercruiser had engine protection

The above really depends on what year model and ECM the engine in question has on it. As stated from the service manual seen in one of the post above, the 1996 and older engine models did offer a power reduction option at one time. But from 1996 and a half on, Mecruiser decided they needed to remove power reduction on the MEFI systems altogether due to safety reasons. What was happening was boats would be running along at high speed with the occupants standing up in the boat then for no real apparent reason the boat would suddenly drop down to 2800 RPM in turn throwing people all about in the boat injuring them. So 96.5 till the introduction of the 555 ecm, Merc did not use power reduction. They did come up with guardian mode that will gradually slow the boat down vs suddenly in the 555 ecm.

pulling wires off sensors WILL NOT DIAGNOSE ANYTHING

it will only tell the ecm of additional problems

On the MEFI system, this depends on what ones were pulled off. Yes pulling a sensor wire would cause a code number. Pulling off a discrete switch wire will not set a code number. The discrete switches just goes to the audio input/output side of the MEFI system. They do not set a code number nor will you see it saved in the history. Now If the drive lube bottle or the transmission temp switch was activated, you would see a general warning 1 or 2 in the live data only as it is happening. General warning 1 or 2 is not saved that I recall.

No turning off the battery will not erase a code number stored in the ecm had you had one.

 

[cdiamond]

Re: Engine alarm help

we sure appreciate

the dissertation

Professor Fun Times

although probably better suited for different audience

let's not lose sight

of the fact that our original poster

is just 'joe boater'

the encouragement of willy nilly

pulling wires or connectors

on an efi system

isn't likely to resolve any issues

or yield any useful information

i'm guessing - that's why they developed Scanners

 

[alldodge]

Re: Engine alarm help

we sure appreciate

the dissertation

Professor Fun Times

although probably better suited for different audience

let's not lose sight

of the fact that our original poster

is just 'joe boater'

the encouragement of willy nilly

pulling wires or connectors

on an efi system

isn't likely to resolve any issues

or yield any useful information

i'm guessing - that's why they developed Scanners

Please instead of attacking lets try to civil, and I will apologize if my rocket science comment offended. We are all here trying our best to help folks out and should be able to disagree with respect of each other.

The term sensor and switch gets pushed together here all the time, so also goes with exhaust elbow and riser. That said, the sensors being mentioned are switches from post 14. They are for Oil pressure, I/O fluid level and engine coolant. Power is supplied to the horn and from the other side of the horn they go to the individual switches previously listed. If any of the switches close they supply a ground which activates the alarm. Pulling the wire off the switch will stop the horn and will do nothing to set a code.

Switch Normal State
Oil Pressure, Normally Open.
I/O Fluid Level on Stern Drive, Normally Open.
Engine Coolant Temperature, Normally Open.
Transmission Temperature on MIE Models, Normally Open.

 

[cdiamond]

Re: Engine alarm help

attack ????? you guys aren't that thin skinned are ya ?

just some light hearted fun

geez - lighten up

 

[BIGALF]

Re: Engine alarm help

Took it for a run today. The alarm went on after about 15 minutes for about 4 seconds then went off. Ran the boat the rest of the day stopped for lunch then went back to the ramp with no alarm. It must be a week connection somewhere. I guess I have to wait until it happens more frequently.

 

[BIGALF]

Re: Engine alarm help

Took boat out again and it ran fine except the horn went on for a few
seconds about 4 then went off. The engine did not go to reduced speed. Ran the boat for the rest of the day with no problems. started and stopped the engine about 4 more times with no issue. I think I need to get it not working more constantly before I get a scanner connected. I don't want to pay for a mechanic to go on a boat ride if it doesn't happen.

 

[alldodge]

Re: Engine alarm help

Took boat out again and it ran fine except the horn went on for a few
seconds about 4 then went off. The engine did not go to reduced speed. Ran the boat for the rest of the day with no problems. started and stopped the engine about 4 more times with no issue. I think I need to get it not working more constantly before I get a scanner connected. I don't want to pay for a mechanic to go on a boat ride if it doesn't happen.

I pretty sure we would all agree of not taking the mechanic for a ride along. With all the time and money spent on this you may want to buy the 400.00 scanner for yourself.

This has been a real puzzler and I have re-read your post many times and I keep going back to post 1. Everything was fine until after you had the impeller replaced, and it then showed up after a few runs. I'm leaning to an overheat issue due to low flow of a temp switch that is closing contact at to low a temp. Did your engine overheat or was this regular maintenance?

 

[84EdH]

Re: Engine alarm help

I never had a boat with ECM or MEFI, or sophisticated alarm systems. So have no knowledge of the electronics. I read with interest the diagnostic approach to solve the OP's problem in the thread. It occurs to me that when such knowledgeable people as have posted above, haven't figured out what is wrong, that maybe, some basic problem solving approach may have been skipped.

An intermittent electrical problem that does not follow a consistent pattern always sounds like a loose wire, intermittent short, or bad connection, until proven not to be to me. If this was my boat, I would put it in the water, start it up at the dock, and wiggle wires and connections in an effort to set off that alarm from dash to stern. Its cheap, you can do it yourself, and you might get lucky and save throwing parts and diagnostic money at it!

Also, can you borrow the scanner for a few hours (without the mechanic), and run the boat until you get the fault?

 

[BIGALF]

Re: Engine alarm help

Just an update of what I have. My 1997 SeaRay 240 (OK022420) has a 5.7LXEFI Throttle Body Fuel Injection system with a Bravo lll outdrive. I'm not sure if I have a MEF1 or MEF2 or something else. New engine long block installed 2007. I was a little to late in changing the BRAVO Water pump impeller for it's annual check before the pump went out on me. I had a mechanic change the impeller pump since I can't do that stuff anymore. He also flushed the system and changed the thermostat.
After that work is when I started having the problem. I thought he might had pulled a wire or damaged a sensor somehow.
My latest run this week had the alarm go on for about 4 seconds then turn off with no engine reduced RPM this time. Keep running the rest of the day with no problem.
It's not that easy to ask a boat repair mechanic to borrow his equipment, so I'm willing to have a mechanic check the system and pay for his skills, but I want to make sure the problem happens when he is there. There is a service mechanic on the water close to where I put my boat, so I will probably use him the next time I have the problem if I can't do it myself. Since, the last trip had only the alarm go on then off in a few seconds, I'm leaning to a loose wire or bad connection somewhere. When I had the boat in the shop last week the mechanic said he cleaned some of the connections that were green and dirty.
I'm pretty sure it should be a wiring issue now so I think I will head in that direction. My first check will be the wires connected below the thermostat that he replaced.

 

[BIGALF]

Engine Alarm help

Engine Alarm help

This is a updated post to my engine alarm issue. My Mercruiser 5.7 EFI throttle body fuel injection has been going on guardian mode (I Think) but I'm now confused. After a short run the alarm will go off and the engine will go on reduced speed. After I stop the engine or just put it on idle then start it up again it will run fine for the rest of the day. We have disconnected all three alarms, Water temper, Outdrive oil, and engine oil and it still went on a reduced mode (reduced speed). Could anything else cause the alarm to go on and low RPM's such as a bad spark plug, loose spark plug wires or anything else? If there is a bad flow of fuel and it chocked the engine could the computer think it was something else and set off the low RPM and then the alarm?

 

[BIGALF]

Alarm Help

Alarm Help

This is a follow up on my problem with my Mercruiser 5.7EFI throttle body fuel injection engine. The alarm has been going off only 1 time after a few minutes run. When I turned off the engine or put it in neutral and ran it again no problem, We disconnected all 3 alarms, one at a time and it still went on low RPM mode without alarm after the third alarm sensor was disconnected. The service guy is confused and changed out the spark plugs and looking of anything else that might cause the reduced RPM mode. Could a back fine send off the alarm for some reason?