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Discussion Starter #1
Hello all,
I just bought my first jet ski a 2000 Yamaha GP 800, i am new to jet skiing and i always wanted one, i ridden multiple jet skis and now i finally got one. i just bought the jet ski in phoenix a couple days ago and i took it to the river for the second time already and everything was going good till the jet ski wouldn't start. It was fine after the fourth ride the jet ski wouldn't start. The seller told me his friend just did a tune up and he was riding a couple times after. When i checked the spark plugs they were very black and smelled like fuel. There is spark going to the spark plugs, I am going to check for compression later today. i don't really know what else to do, maybe something going on with the carb, it does take a couple turns before she fires right up. Any Help will be very appreciated
 

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Gabriel, welcome to the forum.
The blk plugs Id replace with new. sounds like it fouled that set.

What are you using for a compression tester?
Depending on the compression tester you may need a top end. Compression on the 800 should be around 125/135ish. I've found that cheaper gages are very inaccurate. Harbor freight always are way low. At 90psi you'll definitely start having runability issues.
Are you pre mixing fuel or is this still oil injected?
 

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I tested 2 Harbor freight compression testers. I tested them against my snap-on, both Harbor freight gages were about 15psi low. So I don't know that I would trust your readings.

The plugs could be fuel or oil fouled. From the sounds of your post there fuel fouled. Which tells me your due for carb rebuilds. At the same time I'd go over the oil injection system and replace hoses. And check pump set up. The hoses are the weak link in the system. And usually very neglected.

If you don't have a service manual go up to the general pwc discussion tab. Then manuals post. The top post has a link. You'll find downloadable owners and service manuals for your ski.
 

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Discussion Starter #7
Thank your for input. I removed the carbs today and I found a reed valve broken and just seating there intact. Would that cause the jet skit too not start? And there was excessive oil everywhere. Especially in the exhaust.
 

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Yes the broken reed can cause it to not start.
The excess in oil may be indicating an issue with the oil injection. I'd check the cable and setup marks are aligned once the carbs go back on. You have a variable ratio pump controlled by cable from carb. It runs at 200/1 at idle up to 30/1 at full throttle. This requires that the set up mark be aligned to work correctly.

When it comes to carb kits use only true mikuni kits. The cheaper after market kits are trouble. You can find them at Watcon.com, SBT, and several others. Also a link from me under "how to's" tab first post "mikuni parts and kits"
 

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Discussion Starter #9
Ok when I get the reed valves installed I will check into rigging the oil lines. Thank you guys for your help. I appreciate it.
 
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