550sx won't run in water

plaidward

plaidward

Location
Bemidji, MN
Ran it 2 seasons and in August last year it wouldn't start after putting in a bilge. It ran for a bit that day after some praying and then died and wouldn't turn over again.
I cleaned out the start switch and connections and put in a new CDI because the wires were pretty faded and probably cracked.
Brought it back to the beach, could get it to run out of the water but wouldn't stay running in the water.

Stator??
 
plaidward

plaidward

Location
Bemidji, MN
That would make sense, but I really hope that's not it, since it's sat all winter :l

I planned on doing a top end, so I'll know when I pull it apart.
 
Tyler Zane

Tyler Zane

Open Your Eyes
Location
Panama City Beach, FL
May be a fuel issue. On a trailer the demand is low, once in the water under a load the fuel pump may not be able to keep up with the fuel demand.

Ignition would most likely show on the trailer or in water.

Exhaust leak will let you run for several minutes before you start to have symptoms (depending on how bad the leak is) and then suddenly fall on its face. When you pop the hood its pretty obvious you have an exhaust leak most of the time.



Give us a better description. How long does it run? When it cuts out does it stumble or just fall on its face? If you prime it does it start right back up?
 
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plaidward

plaidward

Location
Bemidji, MN
It would fall on it's face after 5 seconds in the water. It's completely stock, so I set the screws at stock settings and half turn adjustments either way weren't affecting the outcome.

@BRANDO6X Can you add anything to this thread?
 
Tyler Zane

Tyler Zane

Open Your Eyes
Location
Panama City Beach, FL
Honestly the only true way to diagnose it would be to check compression, spark, and timing. Once all of those check out, its certainly a fuel delivery issue. Unfortunately since its not easy to check ignition timing on a pwc it makes it a little harder to diagnose. If you are certain it runs good out of the water then I would defiantly lean towards fuel delivery.

Before you go any further I would check compression and be sure you have consistent spark just so you know you have a healthy engine.

If the the ports in the carb venture are clogged then changing the screw settings will do nothing.
 
Nottjbarlow

Nottjbarlow

After reading your symptoms I would agree and say fuel delivery issue, but sometimes if its hard to start initially it helps to pull the pump out of the water.

It's possible your coupler is throwing water into the carb, do you have a cover over it? does it still act funny with a dry engine bay?

If it's rear exhaust maybe too much back pressure?

Try leaning the exhaust out of the water when starting.
 
plaidward

plaidward

Location
Bemidji, MN
I've been working on cars every night this week, and I'm flying out for a wedding this weekend.... It's going to be a while, but I will for sure post updates.
 
plaidward

plaidward

Location
Bemidji, MN
I just pulled it apart, last year I remember reading someone had a similar issue and it was the reeds. Hopefully I can swap em out and start riding again. It's been too long since I've ridden the 550
 
plaidward

plaidward

Location
Bemidji, MN
Put new reeds in and rebuilt the carb.
Had the stiff spring in and read 26-28psi popoff.
When I rebuilt the carbs I noticed the metal check valve had part of it missing and I accidentally(stupidly) bent it slightly while inspecting it.
I wasn't able to get it to stay running off of idle. It seemed to be flooding with any throttle and choking would kill it immediately.
I seemed to have to choke it, start, it would die, then un-choke, and it would run but just idle. seemed to be flooding it at all times and got better until the low speed was at about 1 full turn out.
The high speed wasn't doing anything and once I put the smaller spring in, it was able to pull me but not fast enough to stand up. 1/4-WOT made no difference.
I'm thinking right now I messed up the check valve. It was the metal one that comes from the fuel inlet so it's probably getting an absurd amount of fuel.
I don't have a primer to verify, but I'll get it on the stand tonight to look into it more.
Any suggestions would be great, I'm about to cash in all of my vehicles and toys for something I won't be bitching about on the daily.

Take a look at image in section 1.9, the metal check valve is what I'm referring to.
https://www.shopsbt.com/pdfs/keihincdk2.pdf

The bad part is I can't find parts anywhere. It didn't come in the rebuild kit I got....
 
plaidward

plaidward

Location
Bemidji, MN
Ended up just bending it back and bolting it on in a way that covers the hole.
Found out it was quite plugged and ran great on the stand after a cleaning.
I'll put it in the river to verify tonight.
 
plaidward

plaidward

Location
Bemidji, MN
So, at stock settings and substantial adjustments in carb setting for high and low screws, it only goes about 5 mph and doesn't change between 3/8-WOT. I'm going to do a leakdown test and see if it's the crank seals.
I thought maybe it was rev limiter, so I disconnected it with no change.
If leakdown passes, it seems the next thing to check is flywheel key to make sure it didn't shear and retard the timing.
Any other suggestions are welcome.
 
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