Fuel dumping from overflow tubes

S

snowmaan

New member
Joined
Dec 28, 2003
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61
Age
55
Location
Fairmont MN
My 95 Vmax 800 has developed a fuel dumping issue. Fuel will dump from the vent tubes on each carb as I run the engine and clean it out on a stand. I have checked the float levels without success. They look fine. Could it be the fuel pump check valve (assuming there is one?). Any insight would help.
 

I had a similar problem with a set of TM38's on my SRX, found the o-ring for the needle and seat had deteriorated allowing excess fuel to flow past into bowl even with the needle closed in the seat!
 
Thanks all!! Just to be clear, the rubber tip on the needle is the item that needs replacing? I assume so as there are no "o rings" that I can see.
 
Yamigod...I see you have a few SRX sleds running strong in 1000 ft. I have an 01 that I am putting on the ice for speed running. Would you share clutching and gearing insight with me?

Thanks!
 
There is a rubber o-ring that goes around the needle seat, you'll see it when you remove the seat. You can get them through Yamaha or you can get a metric o ring kit from most any auto parts stores or fleet farm that should have the correct size, I believe it is 7mm id and 1.5mm thick.
 
underneath needle and seats are o-rings that actually seal into the carb body. they age, dry rot , get brittle or bad fuel like ethanol really destroys these. my vmax 800 did same thing. and sure i have some clutch setups for a srx. drop me pm. 3:16 (yammie tony)
 
100.jpg

Here is what I see when I remove the needle/seat assy.
I don't see any rubber orings anywhere...just a brass female receptacle.
 
right on. pull that small screw, lift that brass seat out. install new o-ring. it should fight some to seat back. your problem will be solved. 3:16 (yammie tony)
 
View attachment 54581Found them! They are there but old and hard. The brass "seat" came out really easily ... so I think you guys are right. Thanks so much.. need this thing making 1000' ft passes again!!! Again, really appreciate all of your input!
 
With the new o rings it might be kinda hard to push them back in, i usually put a light film of oil on them before I push them in.
 
Make sure there's no crap stuck under the needles as well. Not sure if V4s have in tank filters but check that no gunk is coming from the fuel tank.
 
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