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40hp cuts out and back in again

power2005

New member
Hi, I have a 2005 Mercury,40hp fuel injected 4 stroke with electric start that has a an annoying problem of cutting out and then restarting right away. It does this usually under load but also at idle, I have had it to two dealers and both say that they can not find the problem.Has any body else had this problem?
 
Does it stall or just stumble? Cutting out is unclear on what it is actually doing. Most all intermittent problems are normally wiring or connector related. Put a timing light on each plug wire and see if it is spark related when it has the problem. The first step to troubleshooting the ignition is go through the wiring completely. Sand all grounds metal to metal. Pull all connectors apart and clean inspect the pins with electrical cleaner and use dielectric grease to put them together. if the pins are not all the same length use a small jewelers screwdriver to push them all the way in from the backside. Clean all the lug connectors with a wire brush and get nice and snug. Inspect all of the wires for breaks, cracked insulation and bare wires, fix as necessary. This is all part of preventive maint and should be done periodically especially after taking out of storage and preping for the summer.
What it is doing is the motor loses power, the starting horn sounds, and the motor then restarts on it's own. all this in less than a second....
 
Check harness connections and ECM connections as its loosing its 12V and thinks has been turned off and then back on...
 
Thanks , I am going to pull the harness connections and check, the dealer said that they checked the ECM and it was good. Because it is a intermittent problem I am suspecting that it is in the harness from the key switch to the motor.
 
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