2000 Merc 175 EFI power loss when warm
EastwoodNorris
Posted 5/3/2016 10:10 PM (#816064)
Subject: 2000 Merc 175 EFI power loss when warm




Posts: 59


Location: Fifield
My engine runs well when cold. Starts fine, planes boat out fine, good mid range and top end power. After it warms up, it wont plane out the boat. It still starts and idles good and has good power if I'm already on plane. It revs fine in neutral but when I put the throttle down it just dogs. Not sputtering, just powerless. If I run my jack plate up to have the prop spin and get the rpm's up, it will get up to power. The voltage regulators were replaced about 8 years ago and I'm wondering if I have a faulty stator.
whynot
Posted 5/4/2016 5:56 AM (#816069 - in reply to #816064)
Subject: Re: 2000 Merc 175 EFI power loss when warm




Posts: 897


Iboats is a great resource for boat issues if you don't get a solid answer here, FYI.
muskymartin67
Posted 5/4/2016 7:14 AM (#816074 - in reply to #816064)
Subject: Re: 2000 Merc 175 EFI power loss when warm





Posts: 798


Location: Delavan, WI
I had a similar issue on a 99 merc 175 it turned out to be a bad ignition coil. There is 6 of them, 1 for each cylinder. What would happen is it would go in limp mode and would not rev over 2000 rpm. Had a marina diagnose mine after throwing a couple parts at it and it still didn't fix it. Hard part is figuring out which one is causing problem without diagnostic equipment. Unless you change them all, or keep switching them individually with a good one until problem goes away. I was a bit skeptical when he told me what it was but problem has never come back, and it was more than 5 yrs ago. Hope this helps. Can't guarantee you have the same exact issue, but it sure sounds familiar.
muskymartin67
Posted 5/4/2016 8:58 PM (#816195 - in reply to #816064)
Subject: Re: 2000 Merc 175 EFI power loss when warm





Posts: 798


Location: Delavan, WI
And I forgot to mention it would only happen when fully warmed up. Never felt it miss when in limp mode just no power. i was told the engine computer was limiting high rpm to avoid potential engine damage and shuts down 3cylinders and only runs the side that doesn't have the problem.
EastwoodNorris
Posted 5/16/2016 5:34 PM (#817355 - in reply to #816064)
Subject: Re: 2000 Merc 175 EFI power loss when warm




Posts: 59


Location: Fifield
The problem ended up being a bad coil. Resistance checks were ok when cold but opened when hot. THANK YOU muskymartin67!!!
muskymartin67
Posted 5/16/2016 8:27 PM (#817383 - in reply to #816064)
Subject: Re: 2000 Merc 175 EFI power loss when warm





Posts: 798


Location: Delavan, WI
You are welcome. I spent a while searching forums on a few sites and couldn't come up w a solid answer so I had to bite the bullet on that one. I'm actually an auto mechanic and do my own work for the most part but that was a tough one to figure out . Glad I could help, good luck on the water.