Mercury 240 EFI M2 Engine Down on Power

[notshort]

Took my boat and fam out for first trip of the season last weekend...engine started ok but I noticed it just didn't sound right as we transited at low speed to open water. When I increased throttle to accelerate, engine didn't respond; just kind of bogged down.

Based on troubleshooting tips from this forum, I tested trigger assembly with a voltmeter and it looks to be bad. Tech manual says resistance should be 1100-1400 ohms; I got 1266 btwn Purple & Blue trigger leads...1273 btwn White & Red trigger leads...and 0 btwn Brown & Yellow trigger leads. I tested trigger multiple times to make sure I was doing it right, always with the same result.

Engine SN is 0E377095. Based on maintenance records from previous owner, engine was R & R'd in Apr 2009. It ran fine last season; plugs were changed Jul 2019; inline fuel filter & water sep filter changed Oct 2019.

I can buy an OEM trigger assembly for about $200 online. Before I do that, just looking for confirmation that I'm on the right track with respect to problem described and my troubleshooting diagnosis.

Thanks in advance...

 

[Tim75]

Yup. The first 2 checks are OK. The third pair shows an issue. There are less expensive triggers out there. I would not buy a used one. You already have one of those.....

It is not that hard a job. But you will need a flywheel puller. Use one for Merc flywheels.

 

[notshort]

Hey Tim75,
Thanks very much for your assistance. Bought a CDI CDM Trigger 6 Cyl (P/N 134-6456-18) and installed last weekend. Optest sat...engine back up around 6,000 rpm at WOT.

I had called a local mobile boat mechanic who was familiar with this engine and he insisted the problem was related to fuel filter in VST.

After reading your reply, I decided to replace the trigger myself...glad I did

 

[Tim75]

Hey Tim75,
Thanks very much for your assistance. Bought a CDI CDM Trigger 6 Cyl (P/N 134-6456-18) and installed last weekend. Optest sat...engine back up around 6,000 rpm at WOT.

I had called a local mobile boat mechanic who was familiar with this engine and he insisted the problem was related to fuel filter in VST.

After reading your reply, I decided to replace the trigger myself...glad I did

Glad it worked out well. A lot of "mechanics" just like to throw your money at problems.