Engine cuts out

[DLM]

2006 Merc 40hp outboard, 3cyc 4 stroke

Recently serviced, now it idles just fine, runs wide open just fine, but say at 1/4 trottle the engine cuts out for a second about every 5 seconds. It does this all the way up to half throttle. I can't tell if it is electrical or fuel. Fuel quality is good as I use stabilizers. I was wondering if maybe a plug got gapped wrong??? but that should show up at idle also. Fuel filters were changed at the recent service also.

Any ideas would be appreciated.

 

[DLM]

to the top

 

[Mav186]

Hi D-
I think I'd be taking it directly back to the facility that recently serviced it. It may have just been a simple oversight on their part, but what you paid for, was the reasonable expectation to receive the motor back in good operating condition.2cents

 

[fishbiker]

Is this a carb model or efi, Merc offered both in 2006???

 

[DLM]

The efi model

 

[fishbiker]

What it sounds like is a lean misfire, on efi stuff the ecu controld the fuel amouts (mapping) check the burn on your plugs, run it in the area it misfires and shut off pull the plugs and check color, light light brown down to white is lean, dark black is rich or electrical problem. i don,t think you have electrical problem as to it would misfire in all ranges most of the time. the fuel pumps sound ok as it is getting enough fuel to run good at full throttle. a trick i use on outboards and motorcycles is to restrict the air going in the carb or throttle body, run it with the cover off and at the air filter/flame arrester box cover the intake hole or holes (sound attenuator that mounts to the end of throttle body) with your hand and see if it improves or gets worse, i know the ecu should supply the right mapping for the efi but that is not always the case, also a tight valve will cause running problems. Hope this helps , threre is many componets that can cause this air sensor map and so on, check all your hoses for cracks , from what you have said it sounds like a leanmisfire almost like a sneeze. skip

 

[DLM]

Problem Solved

As it turns out the problem was bad plug wires. Two were cracked and the third was actually arcing out. I am somewhat embarrassed that I did not spot this myself but maybe it will cause everyone to give a bit of inpsection to your wires.

I am wondering if this is a common problem with outboards. The engine is only 4 years old, I would not have expected to have this type of problem so quickly.

I can't remember the last time I had to change plug wires on my cars, why the difference????

 

[fishbiker]

good find, you don,t see that to much, yamaha had a recall on plug caps which houses the coils , they would arc and run crummy. Its always good to run an engine at night , you can see the arcing. at least it was an easy fix and not an ecu or something. fish on!! good job

 

[Full_Monte]

good find, you don,t see that to much, yamaha had a recall on plug caps which houses the coils , they would arc and run crummy. Its always good to run an engine at night , you can see the arcing. at least it was an easy fix and not an ecu or something. fish on!! good job

Oh Goodie...I've been looking for a way to entertain the neighbors at night.
They already enjoy my running of engines in the driveway during the day.

 

[fishbiker]

LoL got to love the neighbors