Turns over won’t start

[Reddredd]

Hi I have 2 x 2005 gti Le rfi skis. One of which runs fine the other is driving me crazy. It would turn over but not start. I ended up putting the fuel pump off the good one into it and it started so I took it down to the river and put it in started it and was riding around for ten minutes when it just cut out and wouldn’t start again. Since then I have installed a new fuel pump but it still won’t start. I should add that I have to use a jump pack to turn it over as without out it it struggles to turn over and yes battery is fine I just want to get it so it runs before I tackle that problem. Any help appreciated. Having 2 skis the same helps as I can interchange parts to find if that’s the problem part

 

[Crappiedoo]

I would fix the voltage problem first.

 

[Reddredd]

I have it was actually the starter switch so it now turns over without jump pack . The other day it started so in turned it off went and got the hose ready but wouldn’t start again