haulinvols

I have a 2004 Baja 245 with a 496mag. A few weeks ago I started to get an alarm at higher RPM. There was not much of a pattern to it. The tech at my dealer tried several times to duplicate the problem and he could not. There was not a code in the computer. Finaly after hanging out with me all weekend, we caught it and the code read "fuel pump relay circuit". We tried replacing the relay, and the condition continues. Now at 4200 RPM the alarm cuts on and the engine gurdian as well to limit me to 90% of my power. At first it would do it in only rough water, now all the time. There is not anything else happening to alert you to the problem, no stumbling, rough idle ect. Just the alarm. I am at my witts end with this and now the tech wants to tear my wiring harness apart to look for the problem. Has anybody else out there experienced something like this, or could shed a little light on the subject? I am almost confinced it is a computer problem since I would think if it were a loose connection, it would not matter what rpm the motor was turning. Also, since the engine guardian is kicking in, I have been told this should be a hard code and always visible in the computer till a tech removes it. Every time it occures on my boat there is not a code present after the boat is shut off.

Dave_N

Check the "In gear" sensor. If the ECM thinks it is in neutral, it will reduce available power to 90% and reduce the rev limit to 4200RPM. This is easy to check, just watch the "In-gear" status (with a scan tool) when the alarm is occuring. This should also produce a stored overspeed fault with a high frequency count.

Dave

haulinvols

We ran the boat for about an hour with the computer hooked up and all checked out ok. The biggest reason I think it might be an issue with the PCM, is the fact no codes are present. Any time the engine guardian kicks in, there should be a code in the computer. When I take it to the dealer and they hook up to the pcm, no codes are present.

Dave_N

The reason I mentioned the In-gear sensor is that it produces those exact symptoms, it will cause the Rev limit to be reduced and cause overspeed alarm/fault at 4200RPM, but no fault code will be stored other than the overspeed fault. Do you show a stored overspeed fault? If so, what is the frequency count?

Also when you say "no codes were present" do you mean there were no active fault codes or there were no stored fault codes? Or both? Any chance you can post the "freez frame" memory contents and fault log?

Dave

haulinvols

There are not any codes present at all. The only time we will catch a code is when the computer is hooked up to the motor and the alarm sounds. Then we get a code that says "fuel relay circuit" code. We replaced the relay and the condition is still present. I got word from the dealer last night that the Mercury rep is coming to look at my boat this week. It seems to have stumped even them.