Technical question, about a Yamaha...

[dobbinshabby]

I have a 1999 yamaha xl760 waverunner that i just picked up along with a 92 SeaDoo SPI, anywho the reason i'm asking you about the yamaha is because when i asked about the sea doo and got super quick feed back with accurate answers and this forum is great so i'm just giving it a shot with you guys to see if you might just have the answer before you kick me to Yamaha specific forum.

Anywho this is the problem,

Its a 1999 yamaha xl760 that was apparently using too much oil. So i disconnected the automatic oiling system and changed it over to pre-mix, no big deal. Well we get to the lake and on the first run i go wide open throttle and it runs up to 30-35 mph and suddenly dies, as if it just suddenly ran out of fuel. The thing will idle, run half throttle, and slowly all day long with no problems yet when you cram it, it runs up for a bit and then just dies. Starts right back up almost every time also. The few times it does not start right back up, you hit the starter and it acts as if the battery is dead or the motor turns SLOWWWLY for like 1 rotation and quits, that may be nothing but i thought i would mention it. So all in all the problem is when you hammer it, after a while it just spontaneously dies as if it has run out of fuel. The time between when you go WOT and when it dies is not always consistent, it may run for a while and then die or pretty much die right away. Meanwhile the dash is flashing a "No Oil". I'm not sure if it has anything to due with going to premix or not.

Anywho, whatever answer you can give me i appreciate and bear with me about asking you about a yamaha.

Thanks in advance.

 

[Dr Honda]

I had a 2000 XL760. Great ski.

First... you need to short the sender wires to get rid of the warning.

Second... you need to rebuild the carbs before you roast the engine. Also, if it has gray tempo fuel lines... they need changed.

Last... you probably need a battery.

 

[Spimothy Leary]

I had the 98, and I agree, great ski handled well, and tons of storage, good fuel range.

1)yes, shorting the wires will shut down the gauge warning, if you need a manual i'm sure i have one, just pm me and i'll email it.

2)absolutely it would be foolish to not take the carbs out now, and have a good long look at them. do not ride it again until you do. if carbs are not your cup of tea but you can get them out...they can be sent out for clean/rebuild generally for a better price than taking it to a shop,


3) low voltage out of the battery might be causing this, or be contributing, if you have more faith in the condition of the carbs than the battery, then perhaps try one more time to see if that's the cause, and, on second thought i believe that model has a low voltage warning built into the gauge, at least my 760 did and it was a 98 so i'd go back to carbs as #2 on the priority list if your not getting a low voltage warning.

f your the gambling type, and the battery is more questionable than the carbs, then try throwing a good battery in there and see what happens, but if its a carb problem you are risking a seize every time you jamb that throttle so that little experiment will cost you about $400 and the carbs will be coming off anyway when you do a top end rebuild ....

not sure if the 99 had tempo lines i don't think they did but check that anyway.

if this is ONLY happening at wot, and no other occasions, then you need to address the carbs first.

 

[dobbinshabby]

I had a 2000 XL760. Great ski.

First... you need to short the sender wires to get rid of the warning.

Second... you need to rebuild the carbs before you roast the engine. Also, if it has gray tempo fuel lines... they need changed.

Last... you probably need a battery.

I had the 98, and I agree, great ski handled well, and tons of storage, good fuel range.

1)yes, shorting the wires will shut down the gauge warning, if you need a manual i'm sure i have one, just pm me and i'll email it.

2)absolutely it would be foolish to not take the carbs out now, and have a good long look at them. do not ride it again until you do. if carbs are not your cup of tea but you can get them out...they can be sent out for clean/rebuild generally for a better price than taking it to a shop,


3) low voltage out of the battery might be causing this, or be contributing, if you have more faith in the condition of the carbs than the battery, then perhaps try one more time to see if that's the cause, and, on second thought i believe that model has a low voltage warning built into the gauge, at least my 760 did and it was a 98 so i'd go back to carbs as #2 on the priority list if your not getting a low voltage warning.

f your the gambling type, and the battery is more questionable than the carbs, then try throwing a good battery in there and see what happens, but if its a carb problem you are risking a seize every time you jamb that throttle so that little experiment will cost you about $400 and the carbs will be coming off anyway when you do a top end rebuild ....

not sure if the 99 had tempo lines i don't think they did but check that anyway.

if this is ONLY happening at wot, and no other occasions, then you need to address the carbs first.

See i knew i couldn't go wrong asking you guys. Quick and helpful, great site.

Could you guys direct me in the path of finding out which wires to short out for the oil warning and that sort of thing?


Also, Just do a stock rebuild of the carbs or is there some special re-jetting and stuff needed for the premix i'm running?

The battery is also brand new, like literally i put it in after its first charge and took the ski out

also, i see no gray fuel lines. They're blue or green.

thanks.

 

[Dr Honda]

Just rebuild, and clean the carbs. You don't need to re-jet. Also... make sure you change the fuel filter clipped up in the hull, and verify that the fuel select valve is clear.

The wires to short are the sender wires at the oil tank.

I don't care if the battery is new or not. I've seen a BUNCH of bad batteries out of the box. Especially from Wal-Mart, Chief Auto, and interstate.


The fuel lines on it are probably OK. Yamaha didn't use Tempo hoses... but I figured I would ask.

 

[dobbinshabby]

I thought i would update this thread and put some closure to it,

I ordered 2 mikuni carb rebuild kits for it and tore the carbs out and rebuilt them and that solved my problem.

I also shorted the oil wires so that problem is taken care of. So the ski is all set, i've went out and rode it and it runs good. (except for the fact that it has 30lbs of compression on the rear cylinder, but lets just ignore that..)

Thanks!