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Discussion Starter #1
New to forum today...2003 Xlt 800 from slow idle Bogging bad while turning and slight hesitation going straight from dead stop. Changed plugs first, Rebuilt carbs still having the problem. Runs great all other times compression is about 100 on both cylinders, also drained all gas during carb rebuild and changed tank vent due to pressure build up. Any help would be greatly appreciated.
 

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The tank does build pressure when not used and in the sun. The vent lets air in but not out. 100psi is low. Should be closer to 140ish. When you rebuilt the carbs, did you reuse the old needle springs ? Did you set the mixture screws back to factory settings ?
 

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Discussion Starter #3
Does it build enough presssure to blow the cap out of your hand and break the chain?
I read on here not to use the new spring so I didn't on the needle in the carb sort of like a regular float needle. These were mike I carb kits. The only thing I didn't rebuild was the small pump on the top of the front carb and was thinking of doing that next not sure what that one does. I did put the carb back to factory setting and I think it was 1/2 turn out on one and 2 out on the other for both carbs
 

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Discussion Starter #5
Were you talking about high and low speed needles and springs? If so kit didn't come with that I cleaned and put back
 

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anyone have any ideas on what the problem is and what does the small pump on top of the front carb do?
 

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anyone have any ideas on what the problem is and what does the small pump on top of the front carb do?
Rods was asking if you used your old spring from your needle and seat valve inside the carb?
Your problem could be your accelerator pump. Witch is the small pump on top of the first carb. You'll need a new diaphragm and make sure the nozzles in both carbs are clear and clean. They tend to get corroded. You can find the diaphragm at SBT.
 

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There are screws on the side of the carbs. Did ou mess with them, and if so, did you put them back to exactly the setting they were in ?
Dave's right on the rest.
 

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Discussion Starter #9
High and low speed jets were put back exactly and the nozzles were clean I will order diaphram. So should I change springs on needle inside carb while I have it Apart?

Thanks for the help
 

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Dave, do you have the mixture screw settings. I still feel like the low speed is off, so it's best that they're both verified.

Metz1234, your going to need a pop off gauge to double check the spring pressure.
Also note that with as compression drops, throttle response will decrease also. You really do have something going on in the top end if those compression numbers are correct. What are the actual compression numbers for each cyl ? Are you holding the throttle open while cranking ? Make sure the oil lines have not come off, and the cooling lines are clear.
 

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Rodsatheart,
I have high @ 1/2 turn, and low @ 1 3/4. That's what's in my notes and doesn't note any difference for front vs rear carb.

Looking back at posts the compression numbers are a little low. my 800's run in the mid/high 140's on new top end.
 

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Discussion Starter #13
I took apart for this exact reason thinking carbs were fouled put it back together and it runs exactly the same carbs have never been pulled pladtic caps were on base plate screws. I changed oil lines a year ago when they looked bad but still worked. I didn't do wide open throttle when I checked compression will do tomorrow, thanks everyone for responses I scratched carbs to make sure I had exact setting on jets. I ordered accelerator pump diaphram hadn't pulled it apart to look at and not looking forward to pulling exhaust
 

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OK. I may have to apologize here for steering you in the wrong direction. Alot is going to depend on the compression check numbers today. If it is low, you might try turning the pilot screws in 1/16th ONLY if the new accelerator pump does not fix the problem. Have you pulled the plugs to see how the engine is burning ?
 

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The best way I've found to do compression test is to use a wire tie on throttle to hold it wide open while I go about testing. Plus if you have a battery jump box or charger hook it up to help keep battery up during testing. This helps make it more of an even test from cyl to cyl.
 

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Discussion Starter #16
Changed accelerator pump made sure nozzles and hoses were all clean and clear. Installed new plugs. verified low speed and high speed needles are 1/2 and 2 on both carbs. Jet ski ran fine for about 20 seconds then started bogging again. pulled plugs and no oil and not wet at all. Anyone in the North East Houston area good at working on these running out of patience and ideas.
 

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Discussion Starter #19
Update on bogging have not messed with ski in months completely lost interest, still cranked it up and ran it on hose periodically, drained gas and put fresh gas in it, checked compression again with known good Compression gauge and shows 140 on both Cylinders. ordered new plugs, and oil block off. gapped plugs put it water with old plugs ran it around boat ramp for a few minutes to get it warmed up ran great for about 100yds limped back to boat ramp put new plugs in to read plugs, started it couldn't hardly get going limped back put it on trailer plugs are real wet. Does anyone know of anyone in the Humble N.E. Houston area that works on 2003 Waverunner 800? I work on absolutely all my toys from 30' scarab to my diesel truck but I am done with this. any ideas or options would be greatly appreciated. If you interested in working on it and your around Houston I would love to drop it off with you.
 

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What way is the regulator diaphragm oriented ? This is the one that has the metal disk that covers the fuel chamber (needle and seat). The disk should be facing the needle. Verify that the needle arm is parallel with the carb body. Did you bend the arm at any point in time ? Make sure the return line is clear all the way to the fuel tank. Somewhere there is a restrictor in the return system, but I'm not remembering where exactly it is. Could be in the carbs or in line. All that really matters right now is there is a path for excess fuel back to the tank. Did you by chance verify the needle pop off pressure ? Are you sure you are adjusting the mixture screws correctly (ie, the low speed screw is typically the one closest to the base of the carb)? Did you by chance get the mixture screws mixed up (IE, rich and low, they are not the same) ? When you changed the tank vent, did you install it correctly (not a carb related question) ?
Seeing as it seems to run like a stripped ass ape wide open, I'm ruling out ignition problems. On a side not, have you verified that the power valves are operating correctly ?
Trust me, I know how frustrated you are, but you can do this. Think logically. On a carbed automotive engine that was running that rich, what would be the first thing you would look at ? Principles are still the same, they have just added a couple of extra components to the Walbro style carb system on pwc's. It's just a over grown version of the carb on your trimmer.
 
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