boaterh

I am looking for some guidance on a 525 engine issue. The engine only has 25 hours at this point and has not ran correctly since new. For the first 5.9 hours, the engine would not run over 4600 rpm and continuously misfired or studdered as I call it. It sounded like the rev limiter was on at all times. The dealer looked for codes, however, none were found. Around 6 hours the engine started to run up to 5200 rpm, however, it still studders when accelerating, when running between 2500 and 3500 rpm, and when under a load like pulling a tube full of kids. The engine will run along studdering and after a few minutes, it will smooth out and the rpms increase 300 to 500 rpms without touching the throttle. A few minutes later, it starts studdering again and the rpms drop. Also, on some occasions, the gauges cycle from the top of the scale to the bottom of the scale as the needles quiver while running down the lake. Shutting down the engine and restarting correctes the gauge issue. Mercury has troubleshot the engine a couple of times and cannot find any codes in the computer or and other issues. Sorry for the long post. Any ideas????? Thanks

gsmith9898

I would be calling mercury racing since its under warranty.

John B

The shuddering and loss of RPM sounds like you are loosing one or more cylinders. Either they are not firing because of ignition problems or fuel delivery problems, injector or low fuel pressure.

The gage problem sounds like electrical.

Having both of these at the same time, I would quess both may be related ,Electrical!

I would start looking at all the electrical harnesses. Pull them apart and look inside them for terminal problems. Also check all the grounds, from the battery on.

Good luck, John B

Dave_N

It does sound like your are losing a cylinder and it sounds ignition related to me. Possibly arcing to ground at a coil tower or plugwire. The EMI (Electromagnetic Interference) from a high voltage leak like that can really mess with the computer and gauges and even momentarily disable the ECM and never set a fault code.

Hopefully they have some good techs at your dealer, it seems to me that there are not a lot of techs that are super familiar with the wasted spark ignition used on the 525.

Dave

mb_wi

Is this a 10 pin 525 or a 14 pin 525 (engine harness connector)?
Does the erratic operation of the gauges follow the engine misfire?
Be sure to check that all of the plug wires are installed correctly, and none of them are loose on the terminals.

boaterh

Thanks for all the tips. The plugs wires have all been checked as far as being installed correctly. I will have to check on the pin configuration. I'm not sure if it is a 10 or a 14. The gauge issue does not seem to be related to the engine studdering. The gauge issue occurs infrequently, the engine studdering can be repeated any time between 2500 and 3200 RPM.

GOODT

1) find a shop that is intimate with the 525 ( A performance boat dealer )

2) it is a warranty issue so let them handle it

3) do not try to fix it out side of merc warr system

Scott Ferguson

i had the same problem, mine was the switch on the shift cables so you can not rev it up in neutral. unplug it and try again

Wild Card 09

I have a 2006 525 delivered from Merc racing in April. They changed the 525`s to 14 pin (canbus, full digital harness) just before I ordered. It has 40 hours on it and runs like a "five and a quarter" should.
The oil pressure and water temp (Gaffrig monster) gauges have occasionally showed this tremor problem, but will reset if I stop and restart. I have the feeling that it only happens if I am too quick with the ignition (and do not allow the self test to complete itself).
The out of gear revlimiter is set at 2500 rpm and does not sound like your problem.
A faulty plug lead or maybe even a plug itself does not show up as a fault when you scan the ECU, and does sound like the area you (or your Merc racing dealer) should be looking at.

25 hors la loi

If i wait after the gaz pump stop it`s Ok ....cause i am new with a 525
Thank`s again