I had my viper in the garage tonight to try and fix a fuel issue. I thought it fouled a plug out last weekend so I changed them. Didnt help any. It had a low end "loaded up" feeling. I'd get going and it would clear up. So i did the infamous clean the carbs again. Started it up and it ran fine for about 30 seconds. then it gives me a "blurb" sound. Right away i know that it is the fuel pump because my dads viper did this 3 weeks ago. So i take the fuel pump out and take it apart. I cant find anything wrong. It looks fine inside. So i take a spare pump i have and throw it on. start it up 4-5 times and the problem is gone. what am i missing? Is there a problem with my pump im not seeing? I also checked the idle jets (never checked them on this machine). 2 were at 2 turns and one was at 2-1/4 turns! seems like a lot for a stock motor. i put them all at 1-3/4. whats the proper tuning for them? tightem them up til you get a low end bog then out a 1/2 turn?
I have not had much luck disassembling to repair a SRX[same as Viper] fuel pump. The diaphams are very easy to damage and, to my knowledge, there are no repair parts available for these Yamaha Mikuni pumps. A new fuel pump most times is the only cure for pump problems.
If your Viper is stock, set the fuel screws to the stock setting from tech pages.
If your Viper is stock, set the fuel screws to the stock setting from tech pages.
super1c
Super Moderator
1 7/8 for fuel screws is stock for viper. Most run a even 2 turns. Seems to be a lot of idle hang issues this year with the vipers. I would just run the 1 7/8 to 2 turns if no hang. If hang turn them out till its gone.
Can i hurt it if i leave them at 1-3/4 turns? Or should i take it apart again and move them back?
FJViper
New member
If it were me, I would bring them to 1 7/8. Don't know if you had any idle hang issues or not but 1 3/4 is probably a bit too lean. As we all know, lean is bad. Especially these days.
super1c
Super Moderator
FJViper said:
Yup x2. The vipers need their fuel. Even more so after a long pull on the lake and ya let off the gas and jump back and forth between the main, needle and pilots.
10-4
I'll get at it tonight! Better to take the air box out one more time than put a new motor in!
I'll get at it tonight! Better to take the air box out one more time than put a new motor in!
