Help from you mechanical experts

I have a 1998 Sky Supreme with a Merc 350 EFI. I have a problem when the boat is cold it bogs down and only goes a few miles per hour and i have to play with the throttle to keep it from dying. Once it warms up after 5 or so minutes of putting around it seems fine. What could it be? where would you start? fuel filter, plugs, O2 sensor (if they exist on the boat) any tips would be appreciated.

when was the last time you cleaned the metal air intake?

Doe the Idle surge or just start to fade then die?

when was the last time you cleaned the metal air intake?
-Probably a couple years ago when the engine was replaced

Doe the Idle surge or just start to fade then die?
-It surges

Fuel filter should be replaced once a year. Fuel pump, coolant temp sensor aka ECT, throttle position sensor aka TPS, along with other sensors and simple things that can be hard to diagnose like bad gas.

Are you saying the fuel filter is suspect or is that a general statement?

Well depending on the boat it could have two fuel filters. You will have a fuel/water separator then sometimes another one on the feed line out of the tank.

The sensors Peter is referring to also can be the culprit. TPS, and Idle air are the ones I would check first but you need a voltage tester. (a cheap one from a auto parts store will work)


The problem now is trying to figure out what the correct sweep and settings for these two parts, I'd suggest looking for a shop manual on that motor.

Fuel filter: if you didn't replace it last yr, its suspect. replace it now just to be safe.

Choke?

I thought choke too, but he said it's EFI.

New cap, rotor and plugs and it runs like a charm again. The inside of the cap was in rough shape, so i can only assume that was the failure point.