5.0L MPI 2002 Merc engine cuts out for no reason....

[dubie73]

2002 5.0L MPI Merc Crusier with Alpha 1 drive.

Engine cuts out with no warning at various speeds and water conditions. It is like someone just shut the key off. No Audible alarms either
Starts back up immediately and runs 100% until it cuts out again. (I can go idle speed all day and it has never cut out) It seems to be worse while underway or at full throttle.
No audible warnings.
I have checked the following

Replaced Impeller
Replaced fuel filter.
Checked ignition wire connections
Checked kill switch.
Checked grounding
Batteries good
Voltage good
Alternator working good.

Please help. My next step and thinking is the ECM is bad?? What does everyone think? I want to be sure before I drop the $ on a new one that is non-returnable if it is not the problem.
Very frustrated at this.

 

[QC]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Moved to Mercruiser section . . .

Welcome aboard dubie!! We'll get you fixed up, thanks for all the info.

I think you need to run her out of a remote fuel tank to eliminate a pick-up or anti-siphon valve issue. The full load incidents seem to indicate a fuel problem. I am an ignition idiot, but I also hear a lot about overheating coils here. I would not assume ECM.

Wait for others to chime in though.

 

[Don S]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

My next step and thinking is the ECM is bad??

That would be about the last thing I would suspect.
You need to do an engine running wiggle test. Every connection to everything on the engine, the throttle shifter control kill switch, igniton switch, wiring harness etc. and listen to the engine while you are doing it.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

I've gone through every wire harness under the dash and in the eingine compartment both while running underway and no problems. Hit all connections with Di-electric grease also. Does not seem to be a loose wire or bad connection.
The issue clears itself instantly once the motor shuts down. If it was a faulty connection it should happen at idle or low speeds also and it doesn't seem to miss a beat when idle speed.

Just talked to mechanic and he suggested that we check the fuel cooling system? Apparently there is a fuel cooler there because fuel pump is outside of gas tank. He thinks this is possible problem?
I looked for anti-siphon valve and could not find one in my fuel line.
I can suck and blow back into the tank freely from suction fuel line.

 

[QC]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

The fuel cooler is standard on all of the FI models. I am not sure how that could cause a "just shut the key off" type issue. There is an issue with fuel cooling and vapor lock, but those are can't restart, not shutdown.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

That's what I thought. It re-sets itself instantly so a vapour lock or that type of failure does not explain it.

 

[Volphin]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

There HAS been a little consternation on ECMs for this engine... but the symptoms suggest a failure in the ignition. Any codes?

V

 

[svxtech]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

I agree, be sure to check the knock sensor and the shift cut-out switch also.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Did some digging into the fuel system tonight and found what should be the anti-siphon check valve on the fuel line. Took it off and there was no check valve present in it.
Added new anti-siphon in valve in its place and will hopefully load test it in the water tomorrow.

Could this cause the unexpected shutdowns if there was No anti siphon check in the fuel line? My think ing is fuel pump may loose prime due to lack of suction or fuel wanting to fall back in the tank?
Anyone think this theory could be true or am I rambling on in the wrong direction here?

 

[QC]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Wrong direction . . . none equals non-issue. No restriction, they actually check the wrong way . . . towards the engine. Idea is that the fuel won't siphon into the bilge from the tank.

Good safety add, but should not help with your issue.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

I agree, be sure to check the knock sensor and the shift cut-out switch also.

Any idea the location of these?

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Wrong direction . . . none equals non-issue. No restriction, they actually check the wrong way . . . towards the engine. Idea is that the fuel won't siphon into the bilge from the tank.

Good safety add, but should not help with your issue.

Ok thanks for confirming that. I understand the logic on the valve stopping siphon action from happening should you break a line but does that same check valve not restrict flow to the engine as flow is going that same way.......just me thinking outloud off topic and I'm sure has been discussed.

 

[QC]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

but does that same check valve not restrict flow to the engine as flow is going that same way...

Yes, so how does adding one where there is none help your situation?

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Yes, so how does adding one where there is none help your situation?

I agree, its not going to help. I guess I should remove it.
Just thought maybe......I've tried almost everything and am grasping at straws here. It is such a random shut off and instantly clears and restarts. Runs 100% when its running.....lol.
I think it may be time it goes to the doctor and start with a code scan. Hopefully for my sanity there is a fault code that we can work with.

 

[QC]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

random shut off and instantly clears and restarts.

This, despite my earlier comments, says electrical . . .

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Thought I should update the problem and what my repair shop has said in case any one else is having similar problem.

Fuel pump is going and was not putting out constantly and have replaced it. Fairly costly repair so I hope they are correct.
Will take out on the water this weekend and test and let you know if that resolved the issue.

I'm still a bit skeptical that it would always restart and run great. I will take the experts word on it and keep my fingers crossed.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Well, fuel pump was not the problem. Still having same issue...

I guess I will change the engine ECM next......any ideas?

 

[Fun Times]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Well, fuel pump was not the problem. Still having same issue...

I guess I will change the engine ECM next......any ideas?

Do you have the engine serial number you could post?

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Anyone ever have this issue???? I am still having the same problem...Will try to post my serial number tomorrow.

 

[dubie73]

Re: 5.0L MPI 2002 Merc engine cuts out for no reason....

Do you have the engine serial number you could post?

Engine Ser#OM351757