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Michael, Master Mechanic
Category: Boat
Satisfied Customers: 257
Experience:  Over 25 years experience working on everything from PWC's to Mega Yachts
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I have a marine mechanic question and have dealt with Tan on

Customer Question

I have a marine mechanic question and have dealt with Tan on this engine before. I have a 90 hp Evinrude that runs rough at startup after having the EMM replaced
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
Did I miss something here, why has it been two days and no response?
Expert:  Michael replied 1 year ago.

Hi my name is Mike,

Typically when you post here saying that you dealt with a specific expert about your engine issue, Other experts will leave the question for that person. Also, many experts will shy away from vague questions with no additional information about the engine and the issue. Since Tan hasn't responded I will try and help you...

Could you please post some details about your engine i.e year and model number, when the issue started, why you replaced the EMM, any other work done, and anything else you can add to paint a picture of what could be going on here.

If you respond back telling me as much as you can about the issue then I will be able to better help you.


Customer: replied 1 year ago.
It is a Evinrude 90 hp. Model number: E90FPLSSR. Problem initially was that the engine would not start. If we jumped the start delay relay it would turn over. Would not turn over form the key switch though. Found out that the EMM had a circuit that was shorted. We sent it in to DFI to have it fixed. Got the EMM back and the engine turns over. Now the engine will not start very easily when cold. When it does start finally it surges from 3000 RPM down to 1000 uncontrollably. If I try and shift it into gear it dies. I try and restart it and it does the same thing. When I shift into gear the second time it will calm down and run fine. We hooked the computer up, set the timing, found no fault codes. We replaced the plugs, checked the fuel for any contaminants, nothing. I am looking for help straightening this out. Could it be a problem with the EMM, could something else cause this?
Expert:  Michael replied 1 year ago.
Ok, thanks for the info, so your motor is a 2000 year model and there were issues with the EMM's on these motors. From my experience having them repaired has not always been the best way to go. Your issue almost certaily has to do with the EMM as the large rpm surge is the computer malfunctioning or receiving a bad signal from a sensor which would show up on a fault scanner.
Here are a couple things to check/try.....
first check all grounds on the engine and electrical components. A faulty ground can cause the computer to go haywire.
Next, start the engine and when it starts acting up, very carefully push down firmly on the EMM and see it has any effect. A cold solder joint on the main board of the computer could be the culprit and sometimes applying pressure to the EMM will momentarily make the connection and make the motor start running properly.
Try these things and report back with your findings and we'll take it from there.
Customer: replied 1 year ago.
I will try tomorrow and let you know
Expert:  Michael replied 1 year ago.
ok thanks
Customer: replied 1 year ago.
No luck on any of that. Is there a way to test a malfunction in the EMM? I have the computer diagnostics software, no faults are showing up or should I contact DFI to send it back to them.
Expert:  Michael replied 1 year ago.
Ok, we it would have made it easier if you found something tangible but since the EMM is about the only thing that can cause this, then you will need to get it back to them.

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