Easy Fuel issue but im not sure

[Zeon]

So i am new to this, i just picked up an 88 js440. has not been ran in 2 years so i have been told.

i bought it in pieces but its finally pieced back together. Now my issue is i cant keep it running. for that matter even start without starting fluid.

the only way it will run is if i spray starting fluid into the carb. I'm not to familiar with the fuel systems in these. i know i am getting spark...

1) how does the motor suck the fuel in?
2) whats the first thing to look for if the ski is not getting fuel


thanks guys all the help is needed and appreciated

 

[#ZERO]

Here's the Mikuni tuning manual, this will help you to understand the operation of the carburetor and fuel delivery.

http://www.mikuni.com/pdf/sbn_manual.pdf

 

[Zeon]

thanks man.. im downloading adobe reader just to look. it should help a lot. thanks!

 

[cdubb]

Make sure your fuel lines are routed right. Its a fuel problem,did you rebuild the carb?

 

[Zeon]

no i have not rebuilt the carb. i am not sure what comes stock on these but this carb is a mikuni. i have it off the ski and its actually in my lap as im comparing it to the mikuni diagram. it looks like there is 3 inlets for fuel, vacuum or whatever.


any sure way of telling if the carb is bad?

 

[Speedfreak]

If you compare it to the Mikuni guide you can tell that one is an inlet one is an outlet and the other one is a pulse line for the fuel pump. Your carb might not look anything like the pictures in the manual. Look at this rebuild page for pictures of the round body. Mikuni BN

All I can tell you is the little nipple on the very outside of the carb is the pulse line that goes to the crankcase of the motor and then the others should have arrows... But I am not sure... Almost any carb can be rebuilt. just follow the directions and ask questions as you come across them...

 

[Zeon]

heres pics of the carb....

thats the carb....

 

[#ZERO]

Yep... that's the Mikuni BN carb and you will need older manual.

You will have to disassemble the carb to check for internal problems like split fuel pump diaphragms, broken check valves, clogged internal fuel filter, debris, etc.

 

[Zeon]

Ok so there is 3 lines... knew that.. just since you all have WAY more knowledge of this then me... which is which.. i put 1 2 and 3 to stupid proof it for myself

you guys are a great help

 

[cdubb]

If I remember right,2 is the inlet,1 is the return and 3 is to the crankcase.

Im sure Ill get ragged on if Im wrong,wouldnt be the first time

 

[Speedfreak]

#2. is the pulse line that goes to the crankcase of the motor it is the fuel pump.
#1. is the return line that goes back to the fuel tank
#3. is the inlet that comes from the fuel selector valve.

If that ski had been sitting for 2 years you need I mean NEED to rebuild the carb. IF you get it running and the carb isn't supplying enough fuel then you will soon need a new motor to go along with the carb rebuild kit

You can follow the directions in my previous post to rebuild the carb. Just remember watch how it comes apart and take your time. And when you take the carb apart you can see how it works a little better

 

[#ZERO]

If I remember right,2 is the inlet,1 is the return and 3 is to the crankcase.

Im sure Ill get ragged on if Im wrong,wouldnt be the first time

Yep... I agree.

2-Fuel inlet
1-Fuel return
3-Pulse line to the crank case

 

[Zeon]

awe man.. its tough getting advice like this due to the fact of the different answers. well its only gunna work one way.

 

[Zeon]

thanks seriously... this is much needed help i deff needed

 

[Superjet3]

Yep... I agree.

2-Fuel inlet
1-Fuel return
3-Pulse line to the crank case

This is the correct way...

 

[Kaveman]

The easy way to remember where the lines go on a BN as well as an SBN is fuel comes in low (fills from the bottom, when full to the top it more or less overflows) and returns high. The pulse line is in the middle. Yes, I know...so simple even a "kaveman" can do it!

 

[#ZERO]

The easy way to remember where the lines go on a BN as well as an SBN is fuel comes in low (fills from the bottom, when full to the top it more or less overflows) and returns high. The pulse line is in the middle. Yes, I know...so simple even a "kaveman" can do it!

Sorry... the fuel inlet is that white plastic piece number two because the fuel pump check valves are right behind it. The pulse line attaches to number three because that section holds the pulse diaphragm. These carburetors were a bad design because if the fuel pump assembly screws ever came lose during operation, the fuel would go directly into the crank case via the lower pulse line fitting.