Need help with carbs on 96 GTX
- Thread starter jforest
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jforest
Active Member
After rebuilding your carbs...have you guys had to prime the fuel chamber before starting it? I'm thinking that when I take the carbs back off next week when I get the new needle and seats that I will put some fuel in the fuel chamber before putting the carbs back on. I was working on my weed eater and had the carb apart. That carb is setup very similar to ours but hooked up to the fuel chamber is the priming line. I'm thinking that if I prime my seadoo carb, it will help get fuel flowing so the carb isn't just relying on the venturi effect of the carb to draw fuel.
soccerdad
Well-Known Member
Never had to prime the chamber. It is odd that your fuel pump is pushing fuel through the entire system, and not letting any into the jets. It really sounds like you have something in backwards or something. But I cant figure out what. If it is popping off, with air, then fuel should be able to make it to the jets.
jforest
Active Member
I agree. I wish it was something I had on backwards. I've looked everything over atleast 10-15 times and cant see anything that is wrong. I haven't messed with it since I ordered new needles and seats. When I receive them, I'll take everything back apart and ensure that everything is correct. I appreciate your help!
jforest
Active Member
I replaced the needles and seats, put some fuel in the fuel chamber and squirted some fuel down the carb once they were installed. I got the engine to fire and seems to run well. I've shut it off and started it a few times and it starts up everytime. I need to get it to the lake and get it tuned in but I'm very happy that it is running.
Thank you to everyone that has put in their input. I really appreciate the help!
Thank you to everyone that has put in their input. I really appreciate the help!
I'm having a very similar problem with a GTX but havn't rebuilt carbs yet, is that my first step? I've had it running but bogs down at the slightest hint of throttle, and when it was running, I had a full stream of fuel coming out the return line. then othertimes it was emptying the inline full filter quicker than the the tank could replace it, I've looked underneath the hood and can't see any check valves and such so I'm pretty stumped. I've looked at the pic on here and the fuels connected the same, the only difference I've noticed is the pulse box on the mag carb is the other way round, if I'm correct the pulse feed from the crankcase is the straight connector, and fuel feed is the 90' knuckle. Thanks in advance for the help
Rvalentin61
New Member
Fuel tank vent lines
Check on the vent line coming out of the fuel tank. It splits into a "y" and one side goes to a pressure relief valve. The other goes to a one way check valve that allows air into the tank but not out. If it backwards it will cause the problem you have. I know. Wise it happened to me. The one way is the one wit a disk looking thing. The arrow on it should be pointing in or toward the tank. GL.
Check on the vent line coming out of the fuel tank. It splits into a "y" and one side goes to a pressure relief valve. The other goes to a one way check valve that allows air into the tank but not out. If it backwards it will cause the problem you have. I know. Wise it happened to me. The one way is the one wit a disk looking thing. The arrow on it should be pointing in or toward the tank. GL.
soccerdad
Well-Known Member
You should rebuild your carbs and replace the lines if you have not already. I don't pay too much attention to how much fuel is in my inline filter. But you can test by bypassing all the lines/filters/switches. Just hook a line from the RES on the fuel tank outlet to the inlet on the carb. Then see if it happens. You may just be sucking air through one of the many connections.
Thanks for the help, I can't find any check valves or pressure relief valves connected to the vent line however, and I've since noticed that the pulse box on the side of the mag carb is the right way, I'll try what you said about supplying a straight piece of pipe from the reserve to the inlet on the pulse box, is there any test you can do to make sure the diaphragms are working? I remember reading it once about blowing down the pipes but can't remember now.
IDoSeaDoo
Well-Known Member
He means the fuel pump. I'm actually curious myself. I know the diaphragms act as check valves. The pulse line applies alternating pressure/vacuum on the plastic diaphragm, which sucks fuel out of the tank and pushes it into the carb. The check valves make sure it doesn't go back out of the carb, and keeps the fuel flowing one way.
I'm just really stumped as to what it could be,:facepalm: like I said I get a full stream out of the return line when it did run, but it was bogging then I had symptoms of a lean condition by it running away. However, the last time I tried to start it I couldn't even get it to run, it wasn't drawing any fuel what so ever through the inline filter. I even tried blowing down the return line to the tank, which results in a stream out the return of the carbs. I've tried blowing on both the inlet and return individually and both let pressure through blowing and sucking, so I best order one, I've looked and a kit to do both carbs here in the UK equates to 125 dollars, and that doesn't even come with intake gaskets 
that sound about right?
that sound about right?
tkarvelis
Active Member
Since you said that you put fuel in the cylinder, and it fired off, I would temporally rule out the engine for right now. Since you had replaced the fuel lines, did you clean / replace the fuel filters on the carb? There is another post that a member had issues recently with the SBT rebuild kit, so that could be your issue.
IDoSeaDoo
Well-Known Member
When you took your carbs apart, did you blow carb cleaner through the main and pilot jets? What about the orifices where they screw in? Your transition ports (on the pilot hole) should be free, you should have seen cleaner spraying through all 3 (or 4?) of them. Also, what is your pop-off pressure? If your pop-off is set too high (your needle spring is too stiff) you will be keeping your needle closed the entire time. Same thing if you somehow installed your big rubber diaphragm improperly and it's somehow keeping that needle closed. That whole section of the carb is designed to replace the float system seen on traditional carbs (as our skis are just too intense for a traditional float system). Installing that diaphragm wrong or using the wrong one can keep your needle open or closed and cause all sorts of grief. Best way to know if yours is assembled correctly is to do a pop-off test with the carb assembled. You can build a pop-off tester yourself for relatively cheaply. Here's how I built mine
You set the regulator to allow the air to seep in slowly. Attach the hose to the feed barb and close off the return barb. Open the valve and watch the gauge climb. It should cleanly pop at some pressure. Probably in the low 30's for your ski, but verify it in a manual.
Your pop off pressure setting is the pressure the engine has to overcome (by sucking on the carb) to allow fuel to enter the intake. If too high, or you have a case leak, your engine will not be able to build enough vacuum to properly suck the fuel out of the carbs.
You set the regulator to allow the air to seep in slowly. Attach the hose to the feed barb and close off the return barb. Open the valve and watch the gauge climb. It should cleanly pop at some pressure. Probably in the low 30's for your ski, but verify it in a manual.
Your pop off pressure setting is the pressure the engine has to overcome (by sucking on the carb) to allow fuel to enter the intake. If too high, or you have a case leak, your engine will not be able to build enough vacuum to properly suck the fuel out of the carbs.
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jforest
Active Member
Update: After I thought I had it running, I took it to the lake and got it in the water. I had to start it out of the water as it would not start while in the water. I left the ski idling while I parked the trailer and truck. I got on the ski and gave it some throttle and it bogged then died. Didn't have luck getting it started again so I put it on the trailer and went home.
When I got home I took the carbs off and found that the rotary valve cover had two bolts not torqued down completely and were kinda loose. I took the cover off and verified the rotary valve timing while it was off. I installed the cover with a new o-ring. While the carbs were off I sprayed the jets with carb cleaner to make sure they were not obstructed. I got everything put back together and put new spark plugs in gapped to 0.023". A few cranks to get the fuel flowing and it started right up.
I took it to the lake yesterday and put it in the water. It had no issue starting in the water so I put the trailer up and took it out. It responded to the throttle well. I'm in the break-in period since I did a top-end rebuild so I didn't give it much throttle. I pretty much was just cruising around a cove letting it idle and run.
I'd like to thank everyone for their input and help with trying to get this ski running! I really appreciate it!:cheers:
When I got home I took the carbs off and found that the rotary valve cover had two bolts not torqued down completely and were kinda loose. I took the cover off and verified the rotary valve timing while it was off. I installed the cover with a new o-ring. While the carbs were off I sprayed the jets with carb cleaner to make sure they were not obstructed. I got everything put back together and put new spark plugs in gapped to 0.023". A few cranks to get the fuel flowing and it started right up.
I took it to the lake yesterday and put it in the water. It had no issue starting in the water so I put the trailer up and took it out. It responded to the throttle well. I'm in the break-in period since I did a top-end rebuild so I didn't give it much throttle. I pretty much was just cruising around a cove letting it idle and run.
I'd like to thank everyone for their input and help with trying to get this ski running! I really appreciate it!:cheers:
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