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GT40 Fuel Pressure & Stalling

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    Posted: August-13-2012 at 1:05pm
I am having trouble with my 95 ski nautique with a gt 40 motor.

When I go to give it gas (holeshot, like picking up a skiing), the boat is dying. I have cleaned the anti-syphon valve, replaced the fuel filter and no changes.

Saturday I checked the fuel pressure, and are my numbers good or bad.

Idle: 32 psi
When I give it gas it jumps to roughly 40 psi

Then dies out at roughly 2000 rpms.

I'm guessing its either a fuel pump or fuel pressure regulator?

Please help!



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Tim D View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tim D Quote  Post ReplyReply Direct Link To This Post Posted: August-13-2012 at 1:13pm
Did you check the small fuel line inside the fuel control cell? A friend of mine had trouble and the hose had a small crack in it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote storm34 Quote  Post ReplyReply Direct Link To This Post Posted: August-13-2012 at 1:36pm
Just replaced mine as well.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-13-2012 at 1:58pm
Where do I find this?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote storm34 Quote  Post ReplyReply Direct Link To This Post Posted: August-13-2012 at 2:02pm
It's location is in the FCC on the front passenger side of the motor with the high pressure pump and the fuel filter. It connects the pump to the fuel line that feeds the fuel rails.

As for purchasing a new one, I got mine from Vince at SkiDim will all the right gaskets and clamps.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote phkemp Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 4:45am
Panda, I also just changed this hose, my engine was pretty much not running all of a sudden. It's located inside the Fuel Control Cell bowl.

http://correctcraftfan.com/forum/forum_posts.asp?TID=27375&PID=351303񕱇

The FCC and bowl is the black cylinder on the port side of the engine (should be) on the front. Has hoses going in and out of the top. To check the suspect internal hose:

1. Drain gas (and separated water) from FCC bowl. Do this by removing the valve on the bottom of the cylinder, have a quart plastic bowl under it to catch the fuel (and water and probably some gunk) that will come out. Drain it completely. Replace the valve, using some gas-rated thread tape, and tighten firmly.

2. Unscrew the FCC bowl from the top part like you would an oil filter. I used an oil filter wrench that was a bit too loose of a fit, so I put a small wrench under the filter strap, which firmed it up so it wouldn't slip. Put filter wrench near top of cylinder. If you're lucky like I was, it'll unscrew fairly easily and you can remove it. If not...search this forum for "FCC removal" and you'll read of the different ways others got it loose if it was really stuck. It can really be tough to get loose it seems.

3. Once loosened, unscrew and remove FCC bowl; what you should see remaining is the high pressure fuel pump hanging from the suspect hose, and the power wires, with the fuel filter on the pump. OR the fuel filter might be stuck in the bottom of the FCC bowl. Remove the filter from the pump by sliding it off (or if it's in the bottom of the bowl, use some tools to get it pried out.)

4. Remove the fuel pump and hose, you will destroy the crimped clamps while doing so. That's OK.

5. Inspect the hose carefully. Squeeze it all around...you will see a little crack in the hose if it's damaged. Assuming it is.....

6. Call Skidim and ask for a repair kit. It's a dollar. While you are at it, order a new fuel filter as well. The hose will come with new clamps and a new o-ring for the top of the FCC; there will also be one in the new filter, keep this as a spare.

7. Carefully remove the old o-ring from the top of the FCC where the bowl screws in. You need to look up from underneath to see it. DO NOT score or damage the top of the FCC while prying this o-ring out. Put the new o-ring in place, I used a bit of oil to lubricate it, just like you should with an oil filter.

8. Install the new hose on the fuel pump, then to the top of the FCC outlet, using the new crimp clamps. Reconnect the wires to the fuel pump.

9. Slide the new fuel filter onto the fuel pump until it's seated.

10. Feel with a finger to make sure the new o-ring is still in place at top of FCC. Slide the FCC bowl over the fuel pump/filter, and screw it back in. Lubricate the threads with some oil or grease first. Hand-tighten, then finish tightening with oil filter wrench. Don't overdo it!

11. Turn the key one click, and off again, repeating several times. You should hear the fuel pumps kick on for two seconds each time. After 3 or four times, the FCC bowl should have plenty of fuel in it again.

12. Making sure you have water supplied to the freshwater intake, start the engine and see how she runs. Hopefully, your problem is solved at this point.

Good luck.



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PCM GT40 5.8L EFI, 310 HP
Hybridized with Big Air Wake Tower and Bimini
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tim D Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 12:21pm
Somebody needs to post photos of those 12 steps.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 2:06pm
I called skidim yesterday, however my boat does not have a fuel control cell. The GT-40 did not have a FCC until mid 1996. Because I have good fuel pressure, I am going to guess that my problem could be spark related.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote storm34 Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 2:14pm
Originally posted by Tim D Tim D wrote:

Somebody needs to post photos of those 12 steps.


I'd be more than happy to this winter.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Silver15 Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 3:52pm
Luke, I can't really tell from your description. When you were taking fuel pressure readings, did you watch to see what the fuel pressure was doing when the engine was actually dieing?? Still sounds like a fuel issue to me, but that's just my 2 cents.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 4:39pm
The fuel pressure stayed at 40ish the entire time the boat died, no fluctuation. After dying the boat stayed at 40.

I really appreciate the 12 steps being posted. I'm super frustrated because I'd rather be skiing instead I'm working on my boat.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Silver15 Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2012 at 5:40pm
Okay, just making sure. And everything runs smoothly at idle and up to stalling speed? Also, how old is your gas? Perhaps some water got in there, too? It's weird that the stalling occurs consistently at the same speed with no signs of fuel starvation.
If you're interested in investigating a spark issue, one of these would probably work. (Although do be careful buying from Harbor freight; their stuff usually is sub standard quality.) Watch and see if the light quits flickering when the engine begins to die. The fact that it runs good until it hits a certain speed really seems to point towards fuel starving or bad gas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2012 at 5:19pm
Good point, my gas is from last season and early this season (march) even though it had fuel stabilizer in it over the winter, this could be it.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Silver15 Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2012 at 9:24pm
Definitely check that! Gas has a very short shelf life these days. The gas in my Barracuda went bad after only 2 months. I have no idea as to how effective those stabilizers are. Let us know what happens!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-17-2012 at 2:40pm
Originally posted by Silver15 Silver15 wrote:

Definitely check that! Gas has a very short shelf life these days. The gas in my Barracuda went bad after only 2 months. I have no idea as to how effective those stabilizers are. Let us know what happens!


Draining the gas today, wife and I are going to take it out sunday after church! Thanks everyone for your help!

I'll let you know the results!



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Post Options Post Options   Thanks (0) Thanks(0)   Quote panda Quote  Post ReplyReply Direct Link To This Post Posted: August-28-2012 at 1:20am
Forgot to give update, it was bad gas. On a side note, my boat only does 44.8 on gps; is that slow?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bri892001 Quote  Post ReplyReply Direct Link To This Post Posted: August-28-2012 at 1:02pm
Originally posted by panda panda wrote:

Forgot to give update, it was bad gas. On a side note, my boat only does 44.8 on gps; is that slow?


Glad you got it fixed.

As far as the speed, it doesn't sound far off. But, once you get it running smooth and consistent: I would grab your max RPMs, GPS speed, then the full specs on the propeller (diameter, pitch, blades, cup, make and model) and then start a new thread. You're sure to get a ton of input. Many of the the speed/prop experts may not be following this thread.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote phkemp Quote  Post ReplyReply Direct Link To This Post Posted: September-05-2012 at 7:01pm
Ha Ha. If someone needs photos AND the written step by step...um maybe they need to put their wrenches down and head to the shop :-)
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