Hesitation at idle from 1999 Sport Nautique with GT40

[1999Sport]

The last two times I've taken the boat out I've ran into a problem that I haven't read on the forums on here or correctcraftfan.com.

So time to ask you gurus for as much help as possible...

The first few times I start the boat...it stays on for about two second and then dies..unless I keep the idle up for a good 30 seconds to 1 minute. After I do this...the boat has no problem starting again for the rest of the day. Any ideas?
I just recently changed the oil and tranny fluids before the last time out.

Now...the low idle problem....if the boat isn't kept going at a little faster idle then its lowest point...it will die...when attempting to pick up a rider out of the water, you have to dump on the throttle to get past this point..and once its gets going, its fine. If you back off the throttle to a nuetral position ( so the rider can grab the rope/ handle) and then re engage in gear...it will kill itself.

When in neutral the boat idles at around 700 rpm

There is also what almost sounds to be a chatter coming from the transmission, but this only happens at certain times...when some friends and I were out cruising this past time, the noise would go away, and then come back. Any ideas? I've read that it could possibly be the damper plate, as this noise only happens when the transmission is engaged in either fwd or reverse, and never when in neutral.

Any help would be greatly appreciated. I am mechanically inclined...so working on these types of things aren't a problem for me...just not sure where to really start on this one.

[surroundsound64]

RE: Hesitation at idle from 1999 Sport Nautique with GT40

Sounds like problems #1 is due to a cold enging that isn't run (or hasn't been run) very much (lately). I'd first try a dose of Marvel Mystery Oil and cleaning up all the parts that have a tendency to get dirty (plugs and stuff) (if you haven't already).

My boat had the same problem as #2. I finally found it after everything started getting black. The exhaust had a leak and was choking the engine. It ran fine underspeed, but if I didn't keep the throttle in it, it would die when pulled back to idle.

[DanielC]

RE: Hesitation at idle from 1999 Sport Nautique with GT40

You can down load the GT-40 shop manual from this site. It is a 300 page PDF file, so I hope you have a high speed connection. The engines idle is controlled by the ISC-BPA solenoid. (Idle Speed Control-ByPass Air) The manual has a section on diagnosis.

[richard]

Hesitation at idle

Surround64 would you describe how you find the exhaust leak and fix that may helpfue for me as I have similar issue on my GT-40 EFI engine.

[richard]

RE: Hesitation at idle

999spoart, if you engine is fuel injection,your symptom is 90% similar with mine, I found a bad fuel pressure redulator (that leaks gasoline to the vaccum house), after change it idle become nice and will not die at low idle.

[surroundsound64]

Re: Hesitation at idle

Surround64 would you describe how you find the exhaust leak and fix that may helpfue for me as I have similar issue on my GT-40 EFI engine.

I pulled all the panels out of the floor and with the boat turned off in the water I looked to see where the water was leaking in.

[richard]

Tranny noise

Your boat is V-drive?

[knowscc]

RE: Tranny noise

Check voltage at LPP. Have someone key on the ignition while you check voltage at the pump, as it will run for only several seconds. Check fuel pressure at the FCC. Observe if pressure is fixed at idle and begins to drop as engine begins to idle down and quit. What kind of fuel are you using? Alcohol or winter blended fuels will exacerbate this condition. Unplug the MAP sensor harness and see if engine idles better. It will throttle up more quickly, but this step will eliminate a possible lean condition. Replace the spark plugs, make sure you install the correct ones! Noisy drive plate will dissipate if low/inconsistent idle is corrected. Good luck

[surroundsound64]

Re: Tranny noise

Your boat is V-drive?

If that question is for me, no I don't.

[alalor1]

RE: Re: Tranny noise

If all the other advise fails, and your fuel pressure is good (it is easy to check with a cheap fuel pressure gauge, $16 at O'Reilly's auto parts), check your idle speed control. It is that thing that looks like a small toy electric motor next to the throttle plate. It is actually a solenoid that opens and closes, so it lets air bypass the closed throttle plate. It is designed to adjust the idle speed and increase it a little when need it (in a car, when the a/c turns on or an automatic transmission is put in gear). With a voltmeter you should see some power going to it when you are cranking and right after cranking, if it is not getting any power, the computer is failing to tell it to open. If it gets power, take it out (two bolts, easy task) and give it 12 volts with two cables, you should see it opening and closing. If it doesn't, you found the problem. It is the same idle speed control solenoid that comes on the crown victorias, mustangs and other ford vehicles with the 302 and a single throttle plate, so you can get it really cheap and any car parts store. Be careful because some trucks with the double throttle plate have a different one, some have the same one. If it looks the same, it works!
The rattle is possible to come from a too low idle speed. YOu can actually increase the idle speed by adjusting the throttle cable slightly so it does not let the throttle plate close all the way, but this is only a temporary fix.

[1999Sport]

ok..the chatter turned out to be in the strut bushing and that problem is all fixed and done....now, after checking the fuel pressure

1)at the end of the fuel rail - came in around 33-34 psi

2) at the FCC, came in at around the same 33-34psi

according to the motor specs it should be 39psi +/- 3

When the motor is revved up....psi will actually drop to around 30 psi (at both the rail and the FCC)

I'm going to assume that it's not the regulator because the same low pressure is happening at the cell, or am I wrong?

Also, could it be the fuel relay? Maybe the fuel filter is dirty and needs to be changed?

When I changed out the strut bushing I had to remove the gas tank...so when I reinstalled I made sure every hose clamp I could find was nice and tight.

[richard]

Hesitation at idle from 1999 Sport Nautique with GT40

If you have a leak fuel pressure regulator,will cause idle die,the more aculate symptom is when you pull the morse shift to neutual,engine dies. note: a leak fuel pressure regulator don't change the pressure at the fuel rail.

[1999Sport]

Running out of ideas here...here's the latest on the situation.

1) Plugs changed.
2) Distributor cap/ rotor and plug wires inspected.
3) Idle Speed control replaced.
4) Fuel Pressure tested at FCC (correction to previous post......according to the manual for my boat, fuel pressure should be at 39+ or - 3 with the vaccuum hose disconnected from the fuel pressure regulator disconnected) is coming in at around 41-42 psi
5) Voltage at low pressure pump 12v with key on, around 14v with engine running
6) Voltage at high pressure pump is around the same, 12v, and around 14v with engine running
7) Inspected fuel pickup screen inside tank, nothing on the screen to restrict flow
8) Swapped out the starter and fuel relays with each other to see if maybe the problem was there. Problem still persisted.
9) Tightened all hose clamps on the exhaust.

Finally ran the motor out of a gas can. Engine started up fine this way, however it was already warmed up.

Fuel pressure regulator is not leaking into the vaccuum hose, and the engine doesn't die when I pull back to neutral, it dies when I gently pull into gear. Also, when the vaccuum line for the regulator is removed, fuel pressure increases 8 psi. From what I have read, if you pull the vaccum, and fuel pressure increases between 8-12 psi, the regulator is fine.

I have no idea where to go from here as Skidim said to address all tune up issues and change my fuel filter....

What else could there be?

[1999Sport]

*Edit and additions*

10) Cleaned the spark arrestor out with carb cleaner and compressed air.
11) Replaced the fuel filter

I just got off the phone with Vince over at Skidim, he says to:

1) Check the small hose inside of the FCC off of the HPP. I guess the original lines were vinyl and would crack and that replacement kits are made to fix this problem.
2) Check the LPP pump for debris from the gas tank, as there is no fuel filter between the tank and the low pressure pump.

Also...an in line fuel filter can be added to the line between the gas tank and the LPP, which I am going to do to prevent any chance of burning out my pumps.

Anybody know where I can get my hands on the internal hose kit for the FCC? I'm going to call my dealer, but maybe someone else has them as well?

[1998CanadaNautique]

Ski Dim provides the kits free of charge.