300/440/550 js550 motor

[ozzo098]

My 87 550 starts right up but after it gets running hitting the throttle just stalls out. after letting it idle for 5-10mins I can slowly feather the throttle and it starts to accelerate after about 10mins it will start running how it should but still have to be careful on the throttle. After a while of riding it will run how it should and I can hit the throttle full speed with no problems at all. it runs good but it seems to take way to long to warm up. I can't think of anything so any help would be appreciated!

 

[screaming440]

sounds like a fuel supply problem.

water seperator/filter, tank check valve.

dump the water sep if it still has on, change the filted, test the fuel tank pressure by blowing air into the supply line at the carb.

the tank should pressurize and a heavy folow of fuel should out of the line after you stop blowing into the line.

 

[N2 H2O]

Is the ski all stock? Might need a carb rebuild.

 

[ozzo098]

I took off the water Sep and cleaned it out. There was a little sediment on the bottom but not too much. The filter looked alright still I think its pretty new. The lines all looked pretty good, and I tried blowing into the one but no fuel came out when i stopped. The tank is pretty low though. Also I didn't see a check valve anywhere where would it be located? And it is all stock besides the impeller and k&n air filter.

 

[N2 H2O]

The check valve would be on one of the lines coming off of the carb. It's a little plastic piece that has an arrow on it pointing toward the tank. It should be in the first couple of inches of the line

 

[ozzo098]

Well after cleaning out the fuel separator I put filled it with new gas and tried starting it with no success, I figured it was probably because there was no fuel in the lines so poured some down the carb and it fired up then shortly cut out. I did it a few more times but it wouldnt stay running. I don't think its getting past the separator. Like i said before the filter looks pretty clean but i dont know how old it its. Is there anything else it could be or should i still replace the filter?

 

[screaming440]

again remove the supply line from the carb and blow air into it. the fuel system should hold pressure and fuel should come out the hose after you stop blowing air into it. if this does not happen find you leak and fix it.

also there is a hose that goes from the carb to the crank case.

it is the pulse line for the fuel pump. besure it is not cracked, broken or otherwise not seeling.

 

[screaming440]

sorry i missed the post befor this one.

there are 4 lines comming out of the tank they are the two supply lines for NO and RES, one return line from the carb, and one breather.

the first 3 go to the back of the ski and the breather goes forword and up the handle pole(not to the carb as stated above). sometimes the breather has been cut short and just stops a few inches from the tank.

the check valve should be in the breather line near the tank. if not try pinching the breather line and do the pressure test again.

 

[screaming440]

look at this pic.

The check valve is the white plastic part in the fuel line going forward and is about 10 inches from the fuel pickup.

 

[gtgoat]

I have a similar problem that I still haven't work out.

Theory 1: 550's use do have a rev limiter that has been removed. I read that the limiter can slow the fuel returned to the tank under normal conditions. Under red line it cuts off all the fuel to the tank and floods the motor. I'm wondering if the missing limiter is causing a dry carb scenario and starving the motor.

Theory 2: The BN44 has a small diaghram in the carb that was sometimes not cut correctly. When installed it could choke back some of the fuel. I haven't taken my carb apart to test this theory yet either.

 

[ozzo098]

Ok so heres where I am... I blew into the line and nothing happened, i tested the check valve and it seems to be working fine. I looked for a leak and it seemed to be coming from the gas cap under the hood. I took it off and noticed the o-ring had a little piece missing out of it but wasn't broke all the way through. I sealed that up pretty good until the new one I ordered comes. I went back to The hose on the carb and blew into it. It took about about 4-5 big breaths until gas came out. I went to fire it up and nothing happened. Poured some gas down the carb and it started right up but shortly cut out. I dont know whats going on. fhould the gas flow to the carb after one breath or does it take alot?

 

[screaming440]

you may still have air in the line.

did you put the line back on while the fuel was flowing?

did you try prime starting it a few times or just once?

did you check the pulse line for the pump?

it may take a few primed starts to get the air out and fuel flowing again.

 

[ozzo098]

The pulse line looked fine.
I only prime started it twice.
I put the carb line back on while it was still flowing.
How long should the tank stay pressurized after i blow in it and get the fuel flowing?

 

[screaming440]

it should hold pressure and build pressure when it gets hot and moved around.

if you have one that is seeling good it will release a lot of pressure when you take the fuel cap off.

if it was running before and not now i think you still have air in the line.

you may want to prime it a few more times.

 

[ozzo098]

Yes when I took the cap of gas poured out. I will prime start it a few more times tomorrow. I just didnt want to start it over and over and over with it being out of the water.