# Thread: 2004 STX 1200F- Not running

1. ## 2004 STX 1200F- Not running

Greatings from Okinawa Japan,

I have a 2004 STX 1200 that when strarted both on the hose and in water will only stay running aproximatly 5-10 minutes, then dies out (like it's not getting gas. It will start back up after waiting 10-15 minutes but then will cut die again after a few minutes running. The few minutes it is running it excelerates normal. Any help would be greatly apreciated.

Shawn

2. Sounds like a check valve, they let air into gas tank, but dont let fumes out. Try running on the hose with the gas cap loose, that should tell you if its the check valve.

3. Originally Posted by Daveski
Sounds like a check valve, they let air into gas tank, but dont let fumes out. Try running on the hose with the gas cap loose, that should tell you if its the check valve.
Actually the check valve lets out gas fume or even liquid fuel if the fuel tank internal pressure is high enough to overcome the spring force of the check valve - which is about 3~4 psi.

4. You ever have your ski sitting in the sun for a couple hours with half a tank of gas and then open your gas cap? thats a heck of alot more than 3 to 4 pounds of pressure!

5. pm RayinJapan..... he is a member and i believe is in okinawa he can help you

6. Originally Posted by Daveski
You ever have your ski sitting in the sun for a couple hours with half a tank of gas and then open your gas cap? thats a heck of alot more than 3 to 4 pounds of pressure!
Have you ever tried to measure at what psi those check-valve would open using a hand-held vac/pressure gauge like a MightyVac? It's usually at about 3 to 4 psi, maybe sometimes 5 psi.

Then measure the surface area of the gas cap - which is about 9 square inches. The total force exerted on the gas cap due to 4 psi of gas tank internal pressure is:

9 in^2 x 4 pounds/in^2 = 36 pounds

That's how much force exerting on the gas cap.

7. If you have a better suggestion for this guys problem, lets hear it!! Otherwise if you just want to argue with me and try to correct me, TAKE A HIKE!!

8. ## Update

All,

Thanks for all the suggestions. Picked ski up yesterday and looks like the problem was a bad fuel pump relay. Ran on the water hose and no issues yet. Was planning on taking it out today, but now have an issue with other ski (05 STX 12F) It will start up and after about 30 seconds the batt alarm goes off. Battery is charged and all concetions are tight. Now I have to trouble shoot the elec system.

Again thanks for all the helpful suggestions for my ski, I will keep posted after I get it on the water and make sure the relay was the problem.

Shawn