1998 - 196 Nautique surging under load

[pSchwade]

I know this is an old thread, but I just found the problem for my situation. apparently the 60 amp breaker was intermittently tripping and reseting at high RPM's for some reason. I went to start it up to start on the diagnostics and noticed that the fuel pumps weren't running, so I checked the relays (which were fine) and then checked the breaker. When I reset the breaker the pumps would run for a few seconds (just like normal) and then I noticed that if I hit the reset button they would run again... so I tried running it while I had my girlfriend hold the reset in and it ran almost perfectly. So I bypassed the breaker (put all the wires on one post) and took it to the lake for a test drive and it ran perfectly.

I had already installed a battery isolator, so the current from the alternator doesn't even run to the breaker anymore. I also had a problem with the dash loosing power last year, which I assumed was due to not having the alternator tied into the breaker, so I also rewired the power supply to the ignition/dash (and changed to dual supply setup so I could run half of the toggles on the accessory battery and the other half on the starting battery). Let me tell you - the electrical wiring was shoddy at best and not very robust, it looked like someone told a middle school kid where things should be connected and let them figure out how to do it.

So at this point, the boat runs perfectly. Im not exactly sure what is running through the 60 amp breaker anymore because I didn't feel like cutting open the wiring hanes (and all the wiring diagrams were a little too vague) so I would probably be fine bypassing the breaker, but I'm ordering a new one just to be on the safe side.

[pSchwade]

Hi,

Thankyou for the informative and detailed thread.

I actually searched for your thread in the past and have cleaned out the low pressure fuel pump including screen..

I don't think that it is fuel related as I have checked the pressure when the problem occurs and it does not change.

Some days I take the boat out on the water and it runs fine.

I strongly believe the problem is electrical.

I have no idea and am just about ready to sell it

after reading through your post I noticed some differences in the problems that we were having. Mine would start and idle just fine, but surge under load. when it was surging the fuel pressure would drop to 0 and then kick back up (like it was running out of fuel). Im sure you have tried most of these things, but here is a list of the possible culprits that I was considering:

Electrical:
loss of power to fuel pumps - could be caused by relay (there are two, one for both pumps, and one for the ECM), or limp mode (caused by safety circuit)
limp mode - the GT40 only checks for oil pressure and thermostat temp so it would be one of those
safety switch
neutral switch
battery connections/breakers - make sure you are getting good power from the battery, some boats have an inline breaker that is near the battery that has been known to cause problems

Fuel:
low pressure pump - not supplying enough for the high pressure pump, going out/debris
high pressure pump - intermittent failure, not pumping
crack in hose inside FCC - causing lower fuel rail pressure
anti-siphon valve - gets gummed up
crack/leak in fuel line from tank to FCC - air in fuel line
clogged filter - also make sure that the filter is around the HP pump and not in the bottom of the FCC

That was my short list, I'm sure that theres probably lots im forgetting - but at least its a place to start.