Yamaha inboard help PLEASE!

russm

Cadet
Joined
Jun 16, 2008
Messages
7
After several episodes of problems to fix(oil cooler, shift cable boot, etc.) I am stuck on a big problem. The quadrojet carb. The float appeared to be sticking so I removed the carb and had an authorized Yamaha dealer rebuild the carb. Reinstalled carb with a new gasket and the boat idles perfect. Once I'm up to 3k rpms and trying to plane it sputters and jumps. I back off under 3 and runs great. I guess you could say I'm a moron about these carbs but I really need some professional help with this. It's obviously a GM motor 5.0 305. The Yamaha dealer is about 75 miles away and I would really like to run the boat before putting it up for winter. One more note; I did replace the fuel filter. If it needs adjusted, where ? Any ideas to help this poor boy would be DEEPLY appreciated ! Also the boat has coil packs so no cap or rotor button to check. Thank you !
 

triman

Petty Officer 2nd Class
Joined
Sep 30, 2002
Messages
124
Re: Yamaha inboard help PLEASE!

According to my book, the following specs are for the Rochester 4MV on the Yamaha V8
Float level 6.4mm, 1/4 inch
Air valve linkage clearance 0.38mm (0.015in)
Air valve return spring adjusting screw setting 3/8 turn out
Choke valve angle - 27 degrees
Flame arrestor mounting surface to top of accelerator plunger 7.9mm (5/16 in ).
There is no information on jet sizes etc.
Maybe the carbie should be looked at by a carbie specialist rather than a Yamaha fella, as these engines haven't been available for many years.
And yes, I own a Yamaha sterndrive, 5.7L and love it, provided I'm the only one who touches it.
 
Top