My outboard keeps cutting out?

My fuel injected outboard motor keeps cutting out.?

• I'm attempting to help some friends with their outboard motor that's acting up. It's a Mercury Saltwater 200 2-stroke with EFI. It has no problem starting or running at idle. When giving the engine throttle, it will accelerate normally, but you nearly smack your face on the dash as the engine cuts out. One second later, it revs up to the appropriate amount of throttle provided for a few seconds, then cuts back to nearly nothing again. This cycle repeats itself. We eventually had to idle back to the dock from two miles out off shore. My first instinct is that the fuel pump is ready to die, but wouldn't the engine shut off completely when it cuts out? My next thought was water in the fuel tank, but as I stated before, the engine doesn't spit or sputter, and runs just fine at idle. I've read on message boards around the internet that perhaps the tank vent is clogged & therefore not providing enough fuel pressure to the engine. Would removing the fuel cap help to diagnose this problem? If I squeeze the fuel bulb while under throttle, will this help to diagnose a pressure issue? Any assistance someone can provide would be greatly appreciated. Getting the boat loaded onto its trailer to take to a mechanic in this location is a huge undertaking, so I'd like to do whatever I can to help my friends. Thank you.

• Answer:

  Unfortunately, the best help you can offer your friend is to help him load it up and take it to a Merc dealer. As with any EFI engine, the only way to properly diagnose an intermittent problem like this is to run a full diagnostics test with CDS (Mercs' computer diagnostics software). If i had to guess, this sounds like ignition loss, which could be a faulty stator or switchbox, or caused by the engine guardian system dropping cylinders because of an overheat or low oil signal. Save yourself a lot of time and aggravation, and have the engine scanned.