Unable to get my 550SX running after winter.

Joined
Jun 16, 2015
Likes
1
Location
Boise, Idaho
#1
Pulled my ski out this morning (1994 550SX all stock). I don't remember my last ride from last season but it was almost completely out of gas and stayed inside all winter. I charged the battery, filled it up and even with starter fluid I couldn't get it started. I eventually pulled and cleaned the 38 Keihin that's on it. Changed spark plugs after that.

Any ideas on whats going on? I can get it to run for a few seconds with starter fluid but thats about it.
 

Mike W

Infidel
Site Supporter
Joined
Jan 16, 2006
Likes
2,325
Location
North Florida
#2
Pulled my ski out this morning (1994 550SX all stock). I don't remember my last ride from last season but it was almost completely out of gas and stayed inside all winter. I charged the battery, filled it up and even with starter fluid I couldn't get it started. I eventually pulled and cleaned the 38 Keihin that's on it. Changed spark plugs after that.

Any ideas on whats going on? I can get it to run for a few seconds with starter fluid but thats about it.
Sounds like a fuel supply issue. Check your fuel selector for an obstruction, filter, and then open up the carb if those check out.
 
Joined
Jun 16, 2015
Likes
1
Location
Boise, Idaho
#3
I pulled the fuel selector and cleaned it / pumped air through it. Seems to be working fine. My only way to know for sure would be to bypass it. The fuel filter looks to be pretty simple and had some fuel in it when I opened it up. Any other places to look?
 

waterfreek

worst luck ever
Joined
Jul 10, 2010
Likes
0
Location
Powell, Ohio, United States
#4
The coil on my 440 went bad this year for the first time. I was not getting consistent spark so my ski would not run. Also sometimes on the 90s skis the kill switch can be a problem. I took my kill switch apart and confirmed it was in good working order before I figured out it was my coil.
 
Joined
Jan 26, 2014
Likes
49
#5
The Carb Needle Valve might be stuck.

If it runs only on Primer, then dies after the Prime is used up means no other fuel is reaching the Carb Throat.

Usually after a long time in storage, fuel varnish and gum will "glue" the Needle Valve shut and will not pop not allowing fuel into the Low and High Speed Circuits.

Make sure the Needle Valve can easily move up and down when the Regulator Lever Arm is pressed and released.

What is the Pop-Off pressure?
 
Joined
Mar 30, 2013
Likes
32
Location
Riverside, CA
#6
If it runs only on Primer, then dies after the Prime is used up means no other fuel is reaching the Carb Throat.
+1

A vacuum leak will also cause the needle and seat to not open.
It is a common problem on Keihin carbs.

If the carb is still mounted, the "paper clip test" can be used to
diagnose the problem.


Bill M.
 
Joined
Jun 16, 2015
Likes
1
Location
Boise, Idaho
#7
After taking my carb to a mechanic he says everything seems to be checking out (though he's never worked on jetskis he just checked the needle and diaphragm etc). How does a paper clip test work?
 
Joined
Jan 26, 2014
Likes
49
#12
FYI: This works great if the Needle is only lightly stuck.

If it's seized-up and won't budge, it is possible to apply too much force via the Paper Clip accidently bending the Needle Handle and then have the Lever Arm separate from the Needle...

That's why I asked what the Pop-Off pressure was. If you or your Car Mechanic did a successful Pop Test, then that would confirm the Needle Valve is free and would also tell us if the pop-off is right.

How did you clean the Carb? Ultrasonic Cleaner? Parts Cleaner? Degreaser Spray? Did you confirm that the Low and High Speed Circuits are clear all the way to the Carb Throat?
 
Joined
Jun 16, 2015
Likes
1
Location
Boise, Idaho
#13
FYI: This works great if the Needle is only lightly stuck.

If it's seized-up and won't budge, it is possible to apply too much force via the Paper Clip accidently bending the Needle Handle and then have the Lever Arm separate from the Needle...

That's why I asked what the Pop-Off pressure was. If you or your Car Mechanic did a successful Pop Test, then that would confirm the Needle Valve is free and would also tell us if the pop-off is right.

How did you clean the Carb? Ultrasonic Cleaner? Parts Cleaner? Degreaser Spray? Did you confirm that the Low and High Speed Circuits are clear all the way to the Carb Throat?
The paperclip test got it started! I ran it for about 5 seconds and killed it, then waited about 10 min and it started up again without issues. I don't have a hose attachment on this ski so I don't feel comfortable running it more than a few seconds.

Does this mean my diaphragm is bad? or am I ready to hit the water meaning it just needed that extra "push" with the paperclip.
 
Joined
Jan 26, 2014
Likes
49
#14
Hooray! Might just mean that the Needle was stuck before and now it's free allowing fuel to flow and feed the Cylinders. Ride it and see what happens.

The Needle Valve is a spring-loaded plunger or piston type valve. If it's stuck, then it can't open to allow fuel flow...
 
Joined
Mar 30, 2013
Likes
32
Location
Riverside, CA
#15
The paperclip test got it started! I ran it for about 5 seconds and killed it, then waited about 10 min and it started up again without issues.

I am more pessimistic than JC.

The real test is, will it start after sitting for a week? My bet is that
it will need a prime or paper clip to start again.

You just filled the float bowl with the paper clip, that is why it restarted
10 minutes later.

In order to diagnose a hard starting watercraft, you must let it sit
for a week so the float chamber is empty. After sitting for a week,
if it takes longer than 1 minute to start using the choke, the engine
has a hard starting problem.


Bill M.

A typical float chamber will hold enough fuel to start the engine
for a few days.
 
Last edited:
Joined
Jun 16, 2015
Likes
1
Location
Boise, Idaho
#16
I am more pessimistic than JC.

The real test is, will it start after sitting for a week? My bet is that
it will need a prime or paper clip to start again.

You just filled the float bowl with the paper clip, that is why it restarted
10 minutes later.

In order to diagnose a hard starting watercraft, you must let it sit
for a week so the float chamber is empty. After sitting for a week,
if it takes longer than 1 minute to start using the choke, the engine
has a hard starting problem.


Bill M.

A typical float chamber will hold enough fuel to start the engine
for a few days.
Do you recommend replacing the choke with a prime? This carb doesn't seem to have an extra port so where would I add the line?
 
Joined
Mar 30, 2013
Likes
32
Location
Riverside, CA
#17
Do you recommend replacing the choke with a prime?
I never recommend installing a fuel primer! Because if you did, you might
fix the symptom (hard starting) but the mechanical problem will still exists.

Your problem occurred after sitting, did you or a mechanic rebuild your carb
last year (2018, or 2017)? If so, the float diaphragm may be stiff. This can happen
because the aftermarket rebuild kits don't stand up to the ethanol in our gasoline.

Did you ever replace the stock spring?
Has the engine ever been rebuilt or new main seals installed? (The SX Reed 550,
had the best 550 main seals)

Have you reused the reed gaskets?

Keihin (oem) rebuild kits cost ~$85, and so many people choose to pay less $$.
But the oem Keihin rebuild kits last longer because the manufacture took time
to do ethanol testing with their products. So in the long run, oem cost less $$.

Keihin carb base gaskets leak vacuum after 1 use, so I would expect the low speed
(pilot) screw setting to change after reusing a carb base gasket.

The OEM carb settings no longer apply to your ski, because of the 550 is old.

I recommend you look at my pictures, and make a flat sanding fixture with a
piece of glass ~3/16" thick, 220 or 320 emery cloth, and 3M spray 77.



Bill M.

A few other details:

Diaphragm carbs don't like to start with a high idle.

When you choke the engine, pull the choke and hold it closed, and with your
other hand apply the starter. Don't touch the throttle until the engine pops.
Then crack the throttle and start the engine.

After the problem is repaired, set the low speed (pilot) screw using the
"Idle Drop Test."
 

Attachments

Last edited:
Top Bottom