Gt40 surging at high rpms

[Brichter14]

Today when we had the boat out it was running fine until after my first set. Then i went to put it on plane and it started cutting in and out on power. Then the check engine light came on. It is idling fine but is surging at high rpms. The manual said spark plugs or gap, distributor cap, or ignition wiring. What do u guys think?

http://youtu.be/vJKURRAx1Lc

[Brichter14]

Fuel filter?

stumbled on this while searching---

Turns out it was the oil pressure switch connected to the computer. The part failed and sent a false signal to the computer that put the engine into SLOW or limp mode. $27.00 later I am back to full speed. This oil pressure switch notifies the computer when the oil pressure is below 5psi. This puts the engine into SLOW mode which only allows the engine to get to around 2500rpms. The other switch that puts the motor into SLOW mode is the water temp switch. Overheating will cause slow mode. The water switch appearantly from the folks I have talked to is more reliable that the oil pressure switch.


The oil pressure switch is an easy DIY replacement. Oh by the way if your switch has failed and you don't have a replacement handy, you can with caution, disconnect the oil pressure switch. This allows you to run normally until you get a replacement. Be extra careful to watch your gauges until you install the new switch. The SLOW mode will be disengaged for low oil pressure. Make sure you disconnect the correct switch too. There are 2. A larger sending unit for the gauge and a smaller on for the computer. Both are Bell shaped located above the oil filter on the port side of a GT40 engine. The switch I replaced had a tan wire with a black stripe on it connected to it.

[Brichter14]

Any insight on this? I am pretty sure it is going into S.L.O.W. Mode.

[Brichter14]

I disconnected the oil pressure switch and now the boat runs fine. I wasnt sure which one to order so i got both. The one on the engine looks like this one.

http://www.nautiqueparts.com/oilpres...ecandgt40.aspx

but the nautiqueparts site calls for this one

http://www.nautiqueparts.com/oilpres...dgmto2006.aspx

[2001SAN]

my gt40 has the second one.

d.

[DannyG]

My 2001 SAN is having what sounds like this exact same issue. Can someone point me in the right direction to where the oil pressure switch is on the GT-40 engine?