Question

We have 2 yamaha waverunner xl760's (1998) and have been having trouble starting them. We have been unable to get one started and we took it to our marine mechanic and it started in the shop for them every time. We take it to the lake, put it in, and it won't pop. It turns over, but won't catch. The mechanic suggested spraying fogging oil into the carbs and we've done that and it pops but then won't start. Is there something about putting it in the water that changes the starting? The second one is starting fine but is bogging down when we get it over 30mph. We have replaced spark plugs, fuel filter but I'm wondering if we might have debris in the jet. I don't see anything when I look into the jet - is there another place to check? We would love to get them running reliably and it's getting frustrating! Please help!!!