650 Stalling Out After Warm

Larry · Aug 22, 2014

I just got at 650 Superjet that isn't running right. It starts fine, but after about 10 minutes it starts to idle rough and it will stall out when you open the throttle. Subsuquent starts take a while, and usually require pumping the primer. It does this when in the water and when it is on the hose. Motor is stock, single carb, with primer modification.

Any thoughts on where I should start?

Larry · Aug 23, 2014

Today I reset the high and low speed jets to the factory setting. It ran well on the hose, but when I got it to the water it did the same thing.

After it has warmed up when you go to WOT it just dies. Starved for fuel. If is as if the carb bowl was not full. ( I know it doesn't have a bowl).

I pulled the carb. I have a rebuild kit on the way. Maybe it is something in the pump.

Any thoughts on why it is not happening when the motor is cold?

Tyrant1919 · Aug 23, 2014

Check your one-way valve on your gas tank first. Make sure the gas tank can suck air in when needed.

Larry · Aug 23, 2014

Tyrant1919 said:
Check your one-way valve on your gas tank first. Make sure the gas tank can suck air in when needed.

Thanks. I already checked the tank for vacuum. No vacuum when I open the tank. I went and checked the vent. I can blow air into the tank through the check valve. But thanks. That would have been an easy fix.

Ryan999 · Aug 24, 2014

Look at the diaphragm in the carb and based off of what other people already gave you it's possible could be a bad crank bearing

Ryan999 · Aug 24, 2014

try rebuilding your fule pump

Larry · Aug 24, 2014

I am hoping that rebuilding the fuel pump will be the ticket.

Has me stumped is that it happens when warm or after 5 minutes of running.

Bad crank bearing, as in the bottom end, that would not be good. But again why only when warm?

Ryan999 · Aug 24, 2014

after the engine is warm the metal expands making it tighter giving you the rough run I have that on a 96 wave radar

Larry · Sep 12, 2014

Made some fixes and the ski seems to be running much better now.

I rebuilt the carb. The pump side was very gummed up.

Also, the exhaust manifold was not installed properly. One of the bolts was too long, it bottomed out and it would not secure the manifold to the head. As the engine warmed up the metal expanded and the manifold seal got worse, it allowed some water to seep into the cylinder, bogging the engine down.

Hope that fixed it. It ran well today for the hour I had it out.