Another ? for Don

[lfadaol]

2008 Mercury 250 hp Pro XS

After fishing a few weeks back, motor started loosing power then picking up again. Went to get on step and bogged down for 50 to 100 yards, then would only get up to 3200 rpms. Dealership changed a coil and next trip acted up again. Dealer rechecked and could not find anything. Last week made a trip, eight miles down river motor started cutting out, I slowed down and took off again ran fine until late in the afternoon. Started loosing power until boat would not stay on step. when able to stay on step, no more than 3200 rpms, the motor would rev up and down and come off plane again. Closer to the landing ran fine with full power. Brought back to dealer, spoke to him yesterday, ran 20 mile trip with no problems. Asked him to keep and run until acted up. Any info I can give the dealership to help solve this problem?
Thanks



Don, I posted this on BBC and sent many of your possible causes to my dealer. I spoke to them yesterday(11/18/08), and was told Mercury techs had sent them something or information to heat the coils to see if they would fail. They stated they ran the motor in the tank for two hours (11/17/08) and nothing acted up. I asked if the techs from Mercury felt it could be a fuel problem and was told they did not. Today (11/20/08) spoke to dealership and they stated it started cutting out at 3500 rmps, but would not wide open. They changed a fuel pump diaphragm and were going to try out this afternoon. No news yet.

Do you feel the Mercury techs are suggesting the same things you suggested on your BBC post. If not, would it be possible for you to talk to my dealership without hurting any egos or feelings over there? Maybe you can let them know we are related! HA! Why would Mercury not change all the coils, and save all this time wondering what is the cause?

If so my boat is at Cheeks Marine, Alexandria, LA 318-448-8281 (Rusty)

I will be glad to pay for the call and your time.

Thanks and God Bless!

Larry Fadaol

337-280-0546




Modified by lfadaol at 8:20 PM 11/20/2008

[donziman]

larry, i have an 07 300xs that did the same thing that you are describing. 4months untold cuss outs and $8000.00 dollars later (warranty) they replaced the computer and i haven't had a problem in 7hrs running as of yet.

[EuropeanAM]

Larry:

They are likely on the right track- it does sound like you're down at least one cyl.

There are a couple things that should be checked- I'll be glad to speak with them. Feel free to give me a call this morning and we'll discuss how you'd like to proceed. There's also some information I'd like them to "record" on the computer diagnostic system- to send by email.

As far as "changing all the coils"... a valid argument can be made both ways- I try to avoid changing "all"... and for good reasons.

Had one with the "exact same situation" in the last week- two coils and two spark plugs later, customer says it's "much improved". It can be challenging to "catch" the intermittent one, though.