8.1 L 2002 Amberjack

[Raleigh]

At cruise speed, port engine suddenly lost the ability to fully rev and lost power. Sounds rough, and only revs to 3000. This is the second time this has happened. The first time the symptoms just disappeared after doing a compression check, replacing plugs, and installing new spin on fuel filter. Fuel was spotlessly clean. Is there an in line filter on a 2002 Amberjack that's in some secret boat building place? Really acts like a clogged fuel filter, or I'm losing a coil or two. I'm on the mechanics waiting list for two weeks out, so I thought I'd try to figure it out in the meantime.

 

[scoflaw]

8.1's are known to rapidly wear out plugs and ignition wires even when the plugs look OK. You could ohm check your wires but ditch the plugs. Those coils rarely go bad

 

[Raleigh]

Thanks scoflaw, new plugs were installed 5 months ago. I guess it could be the wires, visually they look fine and are routed not to chafe or burn.

 

[Jimmy Buoy]

There is no inline fuel filter in mine, only the spin on water separator. It could also be the engine going into limp mode due to a faulty sensor. One that is sometimes the problem is the water pressure sensor on your raw water pump. If you can make the engine repeat the problem, try disconnecting the wire connection to this sensor and see if the problem clears. Also check for obvious differences between engines for heat (risers, exhaust, transmission, etc) when this happens to rule out obvious problems. Having a laser heat gun really comes in handy for this!

A buddy with a Silverton had a similar issue and after trying almost everything on the engine, they discovered that the transmission was overheating due to the internal fluid pump not working properly allowing it to overheat and putting the engine in limp mode. It took all last season to diagnose that one!

 

[Raleigh]

Jimmy Buoy, Thanks, the transmission did indeed make some "sound", when I pulled out of the channel to anchor and assess the problem, I initially thought we'd caught some debris on the port shaft, we later dived and all was clear. I appreciate the approach that I didn't think about. Sensors and trans. If I can't determine the issue, at least I can guide the technician when he comes out.

 

[Kreole Kid]

Also it could be your iac sensor maybe crapping out or about to.


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[Raleigh]

Kreole Kid, Replaced the IAC, when I changed the plugs, 5 months ago. Also did compression check, all cylinders were strong at 185, and within 2 lbs of each other. Engine has run just fine for 5 months, running almost every weekend for an hour or so. Thank you for your suggestion, because this is baffling.

 

[Raleigh]

Here's the follow up. I finally became exasperated and called in a qualified Mercruiser Technician. The new IAC I installed was bad. How frustrating this has been. But finally repaired. Thanks for all the input.

 

[Kreole Kid]

Here's the follow up. I finally became exasperated and called in a qualified Mercruiser Technician. The new IAC I installed was bad. How frustrating this has been. But finally repaired. Thanks for all the input.

ALL my boating buddies have told me to carry a spare one cause they will let you down when you least expect it. But Geez, brand new out of the box? What's that chances of that?!?!?!?!

 

[Raleigh]

Kreole Kid,

It gets better, my port engine issue...plug wire came loose!!!!

 

[Kreole Kid]

Ahhhhhh, the old wire off the plug ehhh? With that said, you should have heard some noises coming from your port transmission as well because when the engine misfires, you'll hear it in your trannie...

 

[Raleigh]

Kreole Kid,

I did indeed! Thought I had run over a crab trap, so I quickly pulled out of the ICW, thinking a tow had somehow dragged one in the channel. Lesson put into memory bank, in the event it ever happens again.