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I have an 06 merc 30hp efi with remote steer. When the motor idles cold it surges and eventually stalls out. It will restart with no problem. Almost as if the low idle is set too low. If i warm it up i can keep it running on low idle but still surges every so often.

When i hammer down the throttle with a load it will run at full rpm for a few min then slowly start winding down to about 2/3 rpm with the throttle lever wide open. Seems as if its going into safety mode but no alarms being sounded by the motor.

I put brand new premium fuel in before first run this year, and always run with seafoam. It was run out of fuel, fogged, gear oil and motor oil changed before winter storage. I did the plugs, new fuel tank, fuel filter late last season as well.

Not sure if this may be a fuel related issue or a spark issue. Wondering if anyone has come across similar issues in the past.

Thanks in advance for any input to steer me in the right direction before i make an expensive trip out to a dealer.

I'm no expert, but it sounds like fuel starvation to me. I take all the hoses are 12 years old, you may have an air leak and are sucking air, they can degrade inside too over time. My first thought was the filter, I had a car do that years ago, but I see you have a new one. Go over the fuel lines from end to end. Good luck.

Thank you Ady. The fuel line from the tank to the motor was my next target as well. Im going to change out the line and primer bulb and see if that fixes the problem.

Hi M. Bois,

Does the primer ball collapse while under full throttle? If so it's def a fuel starvation issue. This happened to me and I discovered my fuel line to the tank had delaminated inside and was choking off fuel when in high demand. The line looked perfectly fine from the outside and the problem was only confirmed after cutting open the fuel line.

Fuel line could easily be the issue. I had a similar situation a while ago on my dads boat. I replaced and properly gapped the spark plugs and the issue went away.