Engine crankning, alarm sounding but doesn?t start.

RegalEurope

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Hi,

I have two Mercruiser 5,7 MAG MPI with V-drives. The engines are raw-water cooled. After a short trip we took a rest in the marina and when I tried to start the starboard engine again it was just cranking. The alarm that always is beeping when I turn on the ignition is now beeping when I crank the engine. Is the beeping alarm a hint about what?s wrong?

I did a quick inspection and disconnected the cable from the oil pressure switch but I still have the same problem. The
oil level in my transmission was low (Walter gear drive) so I refilled but this didn't help me.

Any ideas?

Best regards from Henrik in Sweden.
 

Fun Times

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Re: Engine crankning, alarm sounding but doesn?t start.

Hi there, What year is the engine? Serial number handy?

While cranking, did you happen to open up the throttle a little bit to see if it will help start it?

On an MPI engine, A no start condition along with the horn beeping has an tendency to be an bad IAC (idle air control valve) and/or a dirty iac muffler provided your engine model has one, not all engine models have the muffler located in or around the throttle body.

Of course this is just a guess on my part, as it really could be a number of other things at play.;)

The correct procedure would to hook up an EFI scanner to see what's really going on.
 
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RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Hi again,

Year should be 2001. Could this be the serialnumber OL676524?

I opened up the throttle but nothing changed. Is the EFI scanner a special tool just for Mercruiser or is it possible to use a scanner for other types of engines?

best regards

Henrik
 

Fun Times

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Re: Engine crankning, alarm sounding but doesn?t start.

Yes 0L676524 would be you're serial number, and you're correct, it is an 2001 engine model.

Looking into this a little further, Your MPI system is not the engine model that I was describing above with the more common IAC failure due to possibly having an dirty iac muffler that would sound the horn along with a no start condition.

Yes your engine model has an IAC as well, but there's a slight difference between the two.

Yes the an EFI scanner is Marine specific vs an auto type scanner.

Look up Rinda technologies techmate scan tools.

Rinda Technologies Marine Diagnostic Tools

Rinda Technologies - MerCruiser Scan Tool Spec.

Also for proper diagnosing, you're going to need to hook up a fuel pressure gauge to see what your PSI is at.

Your MPI system does utilize a fuel pressure sensor that would also sound an alarm.

Here is some general information of the Mercruiser warning horn system, See page 5 / 10,

http://media.channelblade.com/EProWebsiteMedia/3506/Mercruiser warning horns.pdf
 

RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Thanks!

If a oil pressure switch is broken would I have a problems with starting the engine? Or would I just hear the alarm?

Another question is what is the difference between MEFI 1 and MEFI 2 and MEFI 3?

regards Henrik
 

Fun Times

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Re: Engine crankning, alarm sounding but doesn?t start.

On your engine model the oil sensor that is connected to the ECM is called a discrete switch designed to only sound the alarm nothing more.

DISCRETE SWITCH INPUTS
Several discrete switch inputs are utilized by the system to identify abnormal conditions that
may affect engine operation. These switches are used in conjunction with the ECM to detect
critical conditions to engine operation.
The switches which are used with the fuel injection system to detect critical engine operation
parameters are:
Switch Normal State
Oil Pressure N/O
(With Pressure)
Gear Lube Monitor
Level on Sterndrive
N/O
(When Full)
Transmission Temperature on MCM Models with
Two-Speed Transmission
N/O
(When Cold)
Transmission Temperature on MIE Models N/O
(When Cold)

350 Mag MPI And Black Scorpion - Multi-Port Injection Components
FUEL PUMP ELECTRICAL CIRCUIT
When the ignition switch is turned to the RUN position, the ECM will turn ON the fuel pump
relay for two (2) seconds.
When the ignition switch is turned to the crank position, the ECM turns the fuel pump relay
ON causing the fuel pump to start.
If the ECM does not receive ignition reference pulses (engine cranking or running), it shuts
OFF the fuel pump relay, causing the fuel pump to stop.

The difference between MEFI 1, MEFI 2 and MEFI 3 would be basically as the years went on starting in 1993 for marine use, the engine manufacturers started adding more EFI features, sensors, better programming wiring harness etc. etc. Also like most electronic hardware, the technology has become more advanced while the size of the components has gotten smaller. Their just doing the same is all.

Though Mercruiser does not use it any more as they now have their own ECM/PCM, called the 555, The Delco MEFI system also has MEFI 4, 4A, 4B, & 5 out on the market. The 4B is liked in the aftermarket high performance engines as it is designed to handle boost with easier engine management tuning.

Eddie from Young Performance says it best though,
MEFI 1 to MEFI 3
 

RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Thanks a lot for the information.

I?m also thinking of the temperature switch (ECT?). If something is wrong with this one would it stop the engine from starting?
 

Fun Times

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Re: Engine crankning, alarm sounding but doesn?t start.

Thanks a lot for the information.

I?m also thinking of the temperature switch (ECT?). If something is wrong with this one would it stop the engine from starting?
Typically no the ECT will not tell the ECM to not start the engine. What could happen though is if the sensor was reading way too cold even though the engine was warm at 163 + degrees, The fuel delivery would be too high and in turn fouling out the sparks plugs ultimately making the engine not start.
 

RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Ok. The engine was not hot when the problem started...! I will start next week with the job and see what I find.

My last question...for today...the same engine gave me some steam (white smoke) over 1700 rpm. I lost an impeller on this engine in the beginning of the season and there is a risk that some minor parts from the impeller left the impeller house and went in to the engine. Should I back flush or should I search for impeller parts somewhere? I know that a mechanic told me something about where these parts will be found...
 

Fun Times

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Re: Engine crankning, alarm sounding but doesn?t start.

I lost an impeller on this engine in the beginning of the season and there is a risk that some minor parts from the impeller left the impeller house and went in to the engine. Should I back flush or should I search for impeller parts somewhere? I know that a mechanic told me something about where these parts will be found...
It's always a good idea to get the remaining pieces out of the system if you can.

There's not many places they can hide in your system though. I believe both coolers are free flowing with no cheese grater type holes. If it's not in the water hoses it could be lodged in the thermostat.

Here is what your water flow system would look like,
http://www.mercruiserparts.com/Show...r=4835&bnbr=150&bdesc=Standard+Cooling+System
 

RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Thanks for your advice! Take a look in your inbox when you can...!
 

RegalEurope

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Re: Engine crankning, alarm sounding but doesn?t start.

Problem solved. The ignition sensor was damaged.
 
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