Seadoo challenger 1800 carbs

[Renny Lagares]

Hey i have a 97 seadoo challenger 1800... I just put 2 sbt 82.25mm engines in and my pockets are getting thin... I have a fuel issue... I have replaced everything in all 4 carbs w/ mikuni kits and new 67.5 l/s jets and 140 h/s mag and 145 h/s pto jets... It has new springs and levers... Also new needle and seats in all 4 carbs.... Pop off pressure in both mags are 35 and both ptos are 32...

All fuel circuits are clean and ive pressurized the l/s hole and im getting a solid 31psi in both the l/s needle circuits... Ive replaced all the o-rings on the needles...

Rotary plate is set on timing... 150psi all 4 cylinders... No vacuum leaks....

Clean gas tank - 40 gal of 90oct ethenol free gas w/ 32:1 mix... Breakin process

NEW FUEL LINES, FUEL FILTERS AND HOSE CLAMPS

my problem is the boat doesn't want to stay running... Throttle response is horrible (bogs down when throttle up then revs but weakly) not like a 2stroke should respond... I can get it started on land idle 3k rpm throttle response quick... But when i have it in water i can't get them started easy...

I choke it and itll fire up idle for a sec shut down and then its hell to start either one...

I am getting fuel to all 4 carbs... 4 new spark plugs (br8es)

l/s needle 1.5 turn out h/s needle close

stock flame arrestors

plugs aren't getting wet but they are not dry either...

If i spray mix gas w/ a spray bottle into the carbs it start idle smooth until it burns out...

Ive bought everything that i could think off that is replaceable in these carbs and im not getting any results.... I even paid one of the worst jetski mechanics on the face of the earth 300 to check replace rebuild whatever my carbs and all i got was oddball pop off pressures and no starting engines...

I have better results doing it myself...

I am trying to find a solution or maybe somebody on the site that has a repair shop that will be kind to my pockets and i can send the carbs to so they can check and fix, so i can just recieve them back and bolt them in and start riding

as i said in the beginning of the post... These are 2 82.25mm bore engines... I shouldn't have to up the jet sizes or anythihg....

 

[Waterluvr]

What about the fuel pumps, have they been cleaned and rebuild as well? It's pretty easy for a beginner to get the pump disks in upside down on the wrong way of the curve or poke a hole in the grommet.

Do you have the Mikuni manual to run the tests on the pumps? Also remove your impulse line and vacuum check those for any leaks.

 

[hoodmekanik]

ljhygiuyasfvasfdgasdg

 

[Waterluvr]

Those small round plastic disks have a top and bottom side, were your's marked with an indicator line and which way did you install them?

 

[hoodmekanik]

i dont have or even knew there was a manual... im goign to start searching ... and the fuelpumps are built onto the carbs and i replaced all the gaskets and the small round plastics w/ grommets...

and i checked pressure pulling vacuum and putting air... it holds 4psi

 

[Waterluvr]

Double post, oops.

 

[hoodmekanik]

i will check first thing in the morning

 

[hoodmekanik]

Double post, oops.

lol its ok

 

[Waterluvr]

lol its ok

So those disks, they are concave believe it or not and only work one way. Most of them have a blue line marked on them and that is the top side where the grommet enters and passes down into the retainer hole. If they are reversed your fuel pumps wont work properly.

 

[hoodmekanik]

my plastic disks dont have any lines on them but i put them flat on the table and they dont look concaved... so i just put it back together.... im going to put the carbs back together and try them again on the boat

 

[Waterluvr]

You just found your problem (or at least part of it), they should have a distinct curvature to them as the plastic they make those from comes on a roll and they are usually all marked with an ink line to show the top side. If they are flat, they aren't sealing the pump.

All the genuine Mikuni and SBT kits are shipped with marked disks these days, cheaper Winderosa kits do not always have marked discs. You didn't get OEM Mikuni kits no matter how they were presented to you.

 

[grinditout]

Rectifier.

 

[hoodmekanik]

I am buying 4 new mikuni kits from sbt and charging system is working on both engines ... 14.1v

 

[Waterluvr]

I am buying 4 new mikuni kits from sbt and charging system is working on both engines ... 14.1v

That's probably a really good start, do you have the on/off/reserve fuel valves on your boat? Those are known problem childs also for obstructing fuel flow to the pump, SBT has a nice low cost replacement for those. I use a Mity-Vac and recovery canninster to check flow from them and they will usually fail to hold vacuum in the off position when the seals are bad.