1999 Pro Air Nautique - GT40 Stalling... I am stum

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   Hey Everyone...

I just bought this boat about a month ago and it has just over 720 hours. I have read hundreds of threads on here and haven't quite found the solution to my problem yet...

Here is my dilemma..

The motor fires up right away and runs very smoothly, no hesitation, surging or missing. The problem occurs most often if I am at a lower RPM for an extended amount of time. Generally, between 30min and 90 min under 1200 RPMS. The motor begins to run rough for a couple of seconds then will cut out and die. I have saved it from dieing a couple times if I hammer the throttle when I hear it get rough. Once it dies once and I get it started I can generally replicate the problem after only a few min. All gauges look perfectly normal at the point of failure and the fuel pressure on top of the FCC is between 35-40.

Now, this is where it gets a bit confusing so bear with me... How it acts after a kill is very inconsistent.

When this problem first occurred the motor would not fire or would fire and die almost instantly resulting in me having to paddle off the lake. Then if I let it sit for 10 to 30 min it would fire and run perfectly again.

Once I experienced this a few times, I read a lot of threads and talked to several mechanics... this lead me to replace the fuel filter, both relays, Low Pressure Fuel pump, TFI, plugs, plug wires, and the Impeller.

I did one thing at a time and would go hop on the lake and test it out with no change.. the motor is still dying.

The one difference I have noticed is that now after replacing those parts when it dies the motor will fire back up right after a kill and if I pick the RPMs up it will stay generally running (I have had it die once upon acceleration after a kill).

I have also experienced it fire right up and run perfectly again even at low RPMS right after a kill.

This is one of the strangest issues I have ever experienced with a motor..

To recap.... Perfectly running motor randomly starts to run rough after an extended amount of time at low RPM's and will kill. How it acts after has differed.. Have seen everything from not firing at all, fire and die instantly, fire and die in a few min, to fire and run perfectly the rest of the day.

The Kill switch is bypassed and I have replaced the relays, impeller, plugs, plug wires, TFI, Low pressure fuel pump, and fuel filter.

Also, I have drained the FCC several times after a kill to check for water in the fuel and the fuel has been clean every time.

Any help you guys can provide is beyond appreciated as this issue has me stumped.

Thank you!!

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SleddersSummerHobby Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: May-04-2021 Location: MN Status: Offline Points: 3	Post Options Post Reply Quote SleddersSummerHobby Report Post Thanks(0) Quote Reply Topic: 1999 Pro Air Nautique - GT40 Stalling... I am stum Posted: May-04-2021 at 1:52pm
	Hey Everyone... I just bought this boat about a month ago and it has just over 720 hours. I have read hundreds of threads on here and haven't quite found the solution to my problem yet... Here is my dilemma.. The motor fires up right away and runs very smoothly, no hesitation, surging or missing. The problem occurs most often if I am at a lower RPM for an extended amount of time. Generally, between 30min and 90 min under 1200 RPMS. The motor begins to run rough for a couple of seconds then will cut out and die. I have saved it from dieing a couple times if I hammer the throttle when I hear it get rough. Once it dies once and I get it started I can generally replicate the problem after only a few min. All gauges look perfectly normal at the point of failure and the fuel pressure on top of the FCC is between 35-40. Now, this is where it gets a bit confusing so bear with me... How it acts after a kill is very inconsistent. When this problem first occurred the motor would not fire or would fire and die almost instantly resulting in me having to paddle off the lake. Then if I let it sit for 10 to 30 min it would fire and run perfectly again. Once I experienced this a few times, I read a lot of threads and talked to several mechanics... this lead me to replace the fuel filter, both relays, Low Pressure Fuel pump, TFI, plugs, plug wires, and the Impeller. I did one thing at a time and would go hop on the lake and test it out with no change.. the motor is still dying. The one difference I have noticed is that now after replacing those parts when it dies the motor will fire back up right after a kill and if I pick the RPMs up it will stay generally running (I have had it die once upon acceleration after a kill). I have also experienced it fire right up and run perfectly again even at low RPMS right after a kill. This is one of the strangest issues I have ever experienced with a motor.. To recap.... Perfectly running motor randomly starts to run rough after an extended amount of time at low RPM's and will kill. How it acts after has differed.. Have seen everything from not firing at all, fire and die instantly, fire and die in a few min, to fire and run perfectly the rest of the day. The Kill switch is bypassed and I have replaced the relays, impeller, plugs, plug wires, TFI, Low pressure fuel pump, and fuel filter. Also, I have drained the FCC several times after a kill to check for water in the fuel and the fuel has been clean every time. Any help you guys can provide is beyond appreciated as this issue has me stumped. Thank you!!
	1999 Pro Air

SleddersSummerHobby Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: May-04-2021 Location: MN Status: Offline Points: 3	Post Options Post Reply Quote SleddersSummerHobby Report Post Thanks(0) Quote Reply Posted: May-04-2021 at 1:57pm
	I purchased a new Cap and rotor but when I was changing the wire I noticed the Cap had already been replaced. Seemed like it couldn't have been more than a couple years old. I will replace that as well if anyone thinks that could be the driver but all of the connections looked clean as could be.
	1999 Pro Air

Gary S Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096	Post Options Post Reply Quote Gary S Report Post Thanks(0) Quote Reply Posted: May-04-2021 at 3:53pm
	Well since you have already replaced alot of parts there is not much left. One thing you have not is the PIP sensor. It's Fords version of the crankshaft position sensor and they are a common problem right after the fuel system. Major work to to get to them- distributor needs to come out,the gear removed and the shaft has to come out,then it screws right in. Many times people just get a complete distributor part number F1TZ-12127-C. Marine,cars and trucks used the same distributor. Rock Auto has them under 70 bucks. https://www.rockauto.com/en/moreinfo.php?pk=6283470&cc=1127001&jsn=557 This is the one you need with the cast gear to be compatable with your camshaft. If it were me I'd reuse the cap that comes with it but reuse the plastic adapter from your original distributor- the one between the cap and distributor body
	69 Mustang HM SS 95 Nautique Super Sport

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2979	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: May-04-2021 at 3:59pm
	Did you change out the HP fuel pump? Also, the short hose inside the FCC attached to the HP fuel pump can crack with age. The cracked hose can be a bugger to figure out. The crack(s) may be hard to see, but it is an easy fix. JQ
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

Gary S Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096	Post Options Post Reply Quote Gary S Report Post Thanks(0) Quote Reply Posted: May-04-2021 at 4:13pm
	He's got a 99-it was the older models that had a plastic hose in the FCC that caused that,plus the fact his fuel pressure is up where it is supposed to be. He could double check real fast by shutting it off and see how high the pressure remains. My money is on the PIP it has that mo
	69 Mustang HM SS 95 Nautique Super Sport

KENO Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11112	Post Options Post Reply Quote KENO Report Post Thanks(0) Quote Reply Posted: May-04-2021 at 6:01pm
	I'd probably wonder if you checked for spark one of those times it suddenly quit on you.(right after it quit). I'd probably also put a little more of Gary's money on the PIP and if you're gonna replace that or the whole distributor, replace the coil too. Coils can do funny things just like the PIP. Coil part number from PCM is R117008 or you could use a Motorcraft DG 470 or cross reference it to lots of other brands.

1999 Pro Air Nautique - GT40 Stalling... I am stum

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