Carb trouble

[adamzpop]

Seadoo Forum is great! Thanks to everyone who responds.

Got another issue...have a 720 with dual SB 38(I) carbs. Took the carbs apart and cleaned everything. As far as I could tell everything looked ok.
engine started right up. I had the arrester off and could see down into the carbs. when I shut the engine down I could see fuel accumulating on top of the butterfly in the PTO carb..left it alone for a couple of hrs and the thing would not start...took the plugs out and they were dripping wet.I turned the engine over a bunch of times without the plugs in and cleard out the fuel. Started ok after that but I still see the fuel accumulating on the butterfly after shutdown so I know this will happen again

How can fuel continue to move through the carb when the diaphram in not pumping?

Any help will be greatly appreciated.

 

[hardtarge]

needle stuck open.

 

[kustomkarl]

It does sound like the needles are sticking open allowing fuel to be pressured into the carbs. Pull the carbs and recheck your needles and seats. The tab of the needle should be level to the carb body. If you changed your springs and needle and seats like during a rebuild, you will have to check the pop off pressure.

Karl

 

[adamzpop]

Thanks for the reply. I'll pull them tomorrow and take a look...guess I should rig up a pop off guage and check that to.

 

[adamzpop]

went to pull tha carbs this morning and the case was filled with gas almost to the top of the carbs...WOW!..don't have a pop off guage yet but apparentl it needs to be set higher....work in progress...will post results..when I figure it out.

 

[DnE1800twin]

my port side PTO carb was doing the same thing. It turned out to be the needle sticking open.
Like Karl said check the little tang that the needle hangs from. Thats what solved my problem.
Good luck

 

[adamzpop]

Thanks for the input. Tomorrow it will be me vs the carb...hope i win

 

[kustomkarl]

We're here to help, let us know if you get in a jam...

Karl

 

[adamzpop]

Thanks again. The info i have recieved here has been outstanding...nice to know there is a place to turn to (even when you feel stupid for asking)when you get in over your head.

 

[kustomkarl]

The only stupid question is the one you didn't ask...we all had to start somewhere...

:cheers:

Karl

 

[adamzpop]

very strange. took the carbs apart again and everything seems to check out...need a better guage for a more accurat test but the pop off pressure looked to be about 15psi with no leakage prior to pop off . Even if this pressure is wrong for this ski how could fuel flow through the carbs while the engine is not running? The ony thing I can think off is the return line put enough pressure in the gas tank to pop the needle long enough for about a quart of gas to flow. Is this a possibility?If so,then my pop pressure is to low.

Thanks again for all the hepl

 

[kustomkarl]

Have you had the seadoo running since you did the rebuild? I hope you have all the fuel lines on correctly. If the needle is off it would allow fuel to enter the carbs. Is there a chance something was in the needle and kept it open and is gone when you pulled it apart? Something seems strange.



Karl

 

[adamzpop]

I had it running..started right up. After shut down is when I noticed fuel pooling on top of the PTO butterfly. I did the pop test on both carbs before I even exposed the needles. Then I opened the needle covers (what ever it's called) and worked the needles while putting pressure to them...No leakage untill pop off...Perplexed.

Thanks for the input

 

[mudpie]

15 psi seems kinda low, needle should hold 10 psi for 30 secs
checking for air bubbles around needle and seat
pop off should be higher than 15 me thinks?
make sure the round rubber diaprahm is in good shape ,they will get all pushed out of shape and cause running issuses
check the tip of needle , to make sure it isnt grooved and the seat is in good shape, how bout the o-ring that seals the seat? if this is bad it will show on pop off test.
but i think pop off is to low, did you use a re build kit?
if you did was it a mikuni kit? or cheap aftermarket?
if kit was used, did ya change arm or spring?
get specs on pop off for your model and re-check
cause other than fuel tank building pressure this is the only way fuel can get past the needle, and for the tank to build pressure, it would have to have a stuck pressure relief valve and sit in the sun for a bit.
good luck
mud

 

[kirkland]

My carbs had bad diaphragms inside.

While you have them apart may as well put a rebuild kit, I just had problems alot like yours but it may be something else, wonder how all that looked... anyway good luck.

 

[seadoosnipe]

Pop-off or lever...?

Seadoo Forum is great! Thanks to everyone who responds.

Got another issue...have a 720 with dual SB 38(I) carbs. Took the carbs apart and cleaned everything. As far as I could tell everything looked ok.
engine started right up. I had the arrester off and could see down into the carbs. when I shut the engine down I could see fuel accumulating on top of the butterfly in the PTO carb..left it alone for a couple of hrs and the thing would not start...took the plugs out and they were dripping wet.I turned the engine over a bunch of times without the plugs in and cleard out the fuel. Started ok after that but I still see the fuel accumulating on the butterfly after shutdown so I know this will happen again

How can fuel continue to move through the carb when the diaphram in not pumping?

Any help will be greatly appreciated.

I saw in one of your replies, you have a pop off of 15 psi. That's 5 PSI to little. You should have a pop-off over 22 psi. Did you mess with the lever? When you put the carbs back together, if you accidently bent your lever upwards of no more than 1mm from flush, the diaphragm is holding the needle valve off it's seat. Gravity flow is allowing the fuel to drain into your motor.

Mudpie has outlined a host of things for you to go through. I do know, your pop off is to low and draining fuel through the venturi into the engine. That's the typical result. I would also do the test, to see if your system is sealed. When you hook up your airline, you can put your finger over the return line and hold off the 10 psi test pressure.

In the meantime, turn off your fuel selector valve till you solve the problem. You might even be able to start the motor and burn off the excess fuel, with it off.

 

[kirkland]

Diaphragms

Mine were out of shape and pushing down on the needle all the time and it was running bad flooding blackening the front cylinder because the front was worse, it's only suppose to push down when the throttle is pushed down it makes a vacuum and pushes it down, mine were not flexing anymore and were just stuck pushing down all the time, and I had crap everywhere from the old lines........all good as new now.