2001 air nautique gt-40

[brad]

i have a 01 air nautique with the gt-40 with about 200 hours on it and just recently i have had problems at idle with the engine surging, i have spoken to a few people and they have suggested it may be the throttle bypass valve does this sound correct. if not any other help would be appreciated.

Cheers Brad

[brian635]

i have a 00, same motor...same problem. i added some injector cleaner to the gas and that seemed to work for now.

[richard]

2001 air nautique gt-40

My 01 SAN's GT-40 EFI 700hr got same problem,idle rough, if not adjust near 1000-1100rpm will easy die when speed down, I had try additive cleaner to the tank and change new spk plug,no luck,but injector still suspectious,I’ll take out for check..

[brad]

I have tried heaps of things including injector clean, im yet to do leads rotor button and dizzy cap, come on somebody must be able to help me out with my little problem.

[mdboats]

Brad,

Give more details. What is your WOT? Have you checked fuel pressure? Does it run better cold or hot? Does the motor run fine at normal operating speeds 1500 rpms to 3500 rpms?

Do a thourough visual inspection and make sure all wires are connectted. Look to see if you have any fuel leaks. Look for wires that could be touching each other causing an arc. Make sure you have a good battery connection.

Let me know the answers to these questions and I will see if I can guide you in the right direction.

Mark Q

[brad]

I have checked all the basics wires hoses etc and everything seems to be in order, it only does it once it has reached operating temperature and it still revs out to about 4500-4600 at WOT and yes anything over 1000rpm its fine

[mdboats]

Brad,

Check your fuel pressure under load condittions at WOT it should be between 39 - 42 psi.
Check your spark plugs, look for any plugs that show signs of high heat. If you cannot do this you need to get the boat to mechanic who has the tools to properly diagnose this problem. Note do not run Champion plugs in this motor.

Mark Q

[richard]

rough idle

I had a test of the effect of the fuel regulator on my GT-40 due to idle not steady and easy stall when shift to neutral, after many other check, a vaccum tube attach the regulator,when the engine runing at idle, I remove the tube, idle speed faster, when put on, speed lower,this is normal ,but I notice some gas splash from the nose,I doubt this is wrong, any advise?

[Rick]

RE: rough idle

Take a look at the throttle bypass motor shaft Is it corroded (dumb questioa...they all are) Make sure its clean and moves freely My SN does the same thing occasionally and every on I speak to tells me that this is the problem. Mine hasn't gotten bad enough to worry about yet and I have 1200 hrs on the boat/motor.

[richard]

2001 air nautique gt-40

I wanted to replace the T.B. for test but can't borrow one yet, the magnetic valve can move but not open much when rpm changes.