Nautique GT-40 Missing/Rolling Idle

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   So I have a 2001 Air Nautique that has started to have issues. At the end of last season, the boat was missing slightly under load. The miss would come and go.

This season, after de-winterizing the boat, it is missing while at idle (No Load) and also while under a load. Right now it seems like its only one cylinder missing (#2). It has also started to have a rolling idle (rpm goes up and down 100-200 from 750 and will occasionally kill the boat).

Doing a tune up on it, I noticed that the interior of the distributor (the metal cap with the teeth for the hall effect sensor) was extremely rusty. I took it out and cleaned it up the best I can, and replaced the rotor and cap. Also replaced spark plugs and wires. Took the Idle Speed controller off and tried cleaning it up as much as I could (didnt look too dirty). swapped the two ECM relays to see if it changed anything (it didn't though both could be bad). Did a compression check (130-140 on all cylinders).

I tried going through the PCM Diagnositc manual but I don't have all the testing equipment so I tried to do all the resistance checks and what not.

Any ideas? It may be two different problems (rolling idle and missing)

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camprnik Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-01-2013 Location: Monroe, WA Status: Offline Points: 17	Post Options Post Reply Quote camprnik Report Post Thanks(0) Quote Reply Topic: Nautique GT-40 Missing/Rolling Idle Posted: July-04-2013 at 6:51pm
	So I have a 2001 Air Nautique that has started to have issues. At the end of last season, the boat was missing slightly under load. The miss would come and go. This season, after de-winterizing the boat, it is missing while at idle (No Load) and also while under a load. Right now it seems like its only one cylinder missing (#2). It has also started to have a rolling idle (rpm goes up and down 100-200 from 750 and will occasionally kill the boat). Doing a tune up on it, I noticed that the interior of the distributor (the metal cap with the teeth for the hall effect sensor) was extremely rusty. I took it out and cleaned it up the best I can, and replaced the rotor and cap. Also replaced spark plugs and wires. Took the Idle Speed controller off and tried cleaning it up as much as I could (didnt look too dirty). swapped the two ECM relays to see if it changed anything (it didn't though both could be bad). Did a compression check (130-140 on all cylinders). I tried going through the PCM Diagnositc manual but I don't have all the testing equipment so I tried to do all the resistance checks and what not. Any ideas? It may be two different problems (rolling idle and missing)

ac505 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: July-02-2007 Location: United Kingdom Status: Offline Points: 66	Post Options Post Reply Quote ac505 Report Post Thanks(0) Quote Reply Posted: July-04-2013 at 7:19pm
	Replace the FCC filter and the small 2 inch hose in the filter body. It can develop a crack,,often too small to see which can cause this problem. Had a very similar problem on my GT40', replaced the hose just a week or two ago.


camprnik Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-01-2013 Location: Monroe, WA Status: Offline Points: 17	Post Options Post Reply Quote camprnik Report Post Thanks(0) Quote Reply Posted: July-05-2013 at 3:05am
	Thanks for the info! I will check and see what condition that hose is. I do know that the previous owner replaced the whole FCC unit a couple years ago as they wrenched it trying to remove it. I am not sure if that is the cause of my miss though. I seem to be missing at the distributor.

bigwavedave Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: March-08-2006 Location: United States Status: Offline Points: 199	Post Options Post Reply Quote bigwavedave Report Post Thanks(0) Quote Reply Posted: July-05-2013 at 10:18am
	Are you tell me what the FCC filter is? Thanks
	bigwavedave

TX Foilhead Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: February-01-2009 Location: Kingsland TX Status: Offline Points: 2076	Post Options Post Reply Quote TX Foilhead Report Post Thanks(0) Quote Reply Posted: July-05-2013 at 11:10am
	Fuel Control Cell (fuel filters and pumps)

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: July-05-2013 at 12:06pm
	Take a look through this thread: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584&PN=1&title=poor-mans-gt40-diagnosis

camprnik Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-01-2013 Location: Monroe, WA Status: Offline Points: 17	Post Options Post Reply Quote camprnik Report Post Thanks(0) Quote Reply Posted: July-07-2013 at 8:59pm
	Update: So I inspected the FCC internal hose (looks ok, ran some fuel through it and didn't get a leak) Changed the TFI (no change in missing) Changed the Idle control valve (no change in rolling/loping). Another couple bits of info to throw out there. When I take the SPOUT plug out (forcing the boat to run at base timing with no advance) I lose the missing. However the Tach is jumping all over the place and eventually just pegs at its max RPMs (The boat's actual RPMs are not jumping around). Also the Rolling/Loping is soo bad that it will actually kill the engine after a couple minutes (makes setting the timing a pain). Anyone have any other ideas? the Missing seems to be located to one cylinder only, and when I put a light on it, it acts like its not getting enough voltage, or has a bad connection. I have swapped wires around and it has no effect.

lewy2001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234	Post Options Post Reply Quote lewy2001 Report Post Thanks(0) Quote Reply Posted: July-07-2013 at 11:20pm
	Just checking that hose and running fuel through it does not really prove much. That hose has 40psi fuel pressure when supplying the fuel rail. Have you tested fuel pressure?? It does not really sound like a fuel pressure problem. But testing pressure will rule that out. The tach fluctuating has me thinking it may be the stator sensor (PIP) in the distributor.
	If you're going through hell, keep going 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta

Tim D Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-23-2004 Location: United States Status: Offline Points: 2641	Post Options Post Reply Quote Tim D Report Post Thanks(0) Quote Reply Posted: July-08-2013 at 2:58pm
	Check the distributor cap for cracks.
	Tim D

camprnik Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July-01-2013 Location: Monroe, WA Status: Offline Points: 17	Post Options Post Reply Quote camprnik Report Post Thanks(0) Quote Reply Posted: July-10-2013 at 1:42pm
	UPDATE: So it appears I have found the problems. The low pressure fuel pump had debris in it (just on the little screen inside it) and between that and a new fuel filter in the FCC, it eliminated the rolling/looping. For the missing, I went through the distributor again, and the Stator (specifically the magnet for the hall effect sensor) and the round cap with the teeth were pretty rusty. I cleaned those up and the miss has disapeared. I am plannin on replacing the stator (have a new one in a box) but the round cap with the teeth I havent been able to find a good replacement unit for that. It's pretty pitted on the inside of the teeth. Took the boat to the lake last night, idles and runs great.

ac505 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: July-02-2007 Location: United Kingdom Status: Offline Points: 66	Post Options Post Reply Quote ac505 Report Post Thanks(0) Quote Reply Posted: July-12-2013 at 7:07am
	how does the LP pump seal? Can you take it apart, clean the mesh and put it back together without a seal kit?

Nautique GT-40 Missing/Rolling Idle

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