300/440/550 JS 550 will only start with 1/4 throttle
- Thread starter Tom54cat
- Start date
could be a number of things first off would be the low end carb settings. but if it idles fine after start that is not it. are you starting it in or out of the water because mine does not start with out some throttle out of the water but under the load in the water it starts fine.
idles fine and i stalled a primer thinking the same thing and it doesnt matter in or out of water...real bugging me :crying:
- Location
- Nampa, Idaho
Replace the fuel line going to the bottom of the carb they get worn out fast and suck a bit of air at times and make it hard to start but yet will keep running once started.
Also, Make sure your choke isnt stuck open a little! Those are the fastest/easiest/cheapest options to start with.
Also, Make sure your choke isnt stuck open a little! Those are the fastest/easiest/cheapest options to start with.
No choke just primer replaced the lower line any other ideas?
is it running a a rpm that is to fast for idle at 1/4 throttle ? it may just need the idle screw turned out not the fuel mix needle but the screw that holds the butterfly valve open more . any ways i was saying that the low end throtle needle controls the fuel / air mixture at 1/4 throttle and lower... i would change the settings on it and see if that helps. manual states to adjust it in until it idles as fast as possible then check throttle response if it boggs when you hit the throttle from idle you need to turn it back out 1/8th a turn and then try again and so on again and again until it responds good. i started mine at 2 full turns out and then worked my way back in. the high end needle and low end needle should not be at the same settings. because the engine needs more air and loss fuel at low rpm and more fuel and less air at high rpm .
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- Location
- 3 stacks and a rock, California
I have this problem with my SX when it starts getting dirt/sand in the carb. pull the carb apart and spray everything down with carb cleaner and re assemble before you mess with any of the settings on the carb.
yepp i have to lay on the starter for 20 sec before it fires wonce its running it ok.........need to do a comperion check i think
screaming440
The Old Skool Professor
- Location
- KC/Lake of The Ozarks
it is not uncommon to have to open the throttle a bit to get one of these started. the long cranking time though could be a weak ignition or it could be the carb.
if this is a carb problem you are either over fueling or under fueling the motor. if over fueling you are adding air by opening the throttle to get it runing. if you are under fueling opening the throttle is allowing fuel to be pulled out of the other circuts.
the fueling for low throttle opening is controled by the regulator portion of the carb. so check your pop off pressure. if that checks out play with the pilot screw, the lowest screw on the carb (i am assuming you have a 44mm bn) and see if anything changes.
if this is a carb problem you are either over fueling or under fueling the motor. if over fueling you are adding air by opening the throttle to get it runing. if you are under fueling opening the throttle is allowing fuel to be pulled out of the other circuts.
the fueling for low throttle opening is controled by the regulator portion of the carb. so check your pop off pressure. if that checks out play with the pilot screw, the lowest screw on the carb (i am assuming you have a 44mm bn) and see if anything changes.
Just did a psi check on cylinders 100 in each i think they are supposed to be around 120 but i really dont know if this is the problem .........iv gone up and down with the pilot and no diff at all........and yes its the stock carb minkcrapi bn .........
screaming440
The Old Skool Professor
- Location
- KC/Lake of The Ozarks
compression should be around 120 on a good motor with a stock head. 100 psi is a little low probably not helping the problem.
if your do anything else check popoff.
the only way to really check the ignition is with a scope,not real easy to do on a jet ski. there are some other ignition tests but they are not 100%.
if your do anything else check popoff.
the only way to really check the ignition is with a scope,not real easy to do on a jet ski. there are some other ignition tests but they are not 100%.
