bbmac

I need some advice. My 7 is running stupid rich and I can't firgure the damn thing out. I have replaced the needle and seat valves, adjusted floats and rechecked about 6 times, cleaned the hell out of the carb, bypassed the return line one way valve near the carb, changed fuel pumps(stock ones), checked vacuum lines and I am still getting 8mpg. do you guys know of anything being weird on the carbs or what couls possibly going wrong?????? please help!!!

Rx7carl

Why did you bypass the return restrictor? Thats not a good idea. When the car is running at idle, whats the float level look like in the bowl windows? And also look into the carb throat to see if theres gas leaking/pouring/dripping down into the carb barrels at idle, cause there shouldnt be any.

Tanjo

Ya, i get crappy gas mileage too, but i just figured that its becasue its a rotary.

bbmac

when I say 8 mpg I am not being sarcastic. I went 130 kms on 66 litres of gas or 75 miles on 16 gallons?. no gas dripping inside the carb, I had that problem once before and corrected it. I bypassed the return line valve because i went through 4 and couldn't get one that worked, thus cause high pressure in the carb and causing gas to spill out of the float bowl air vents.

Also is bypassing the valve really that serious? what are the consequences????

bbmac

the gas level is around half but I am could be wrong as I have not looked in about a week or two.

Rx7carl

Bypassing the valve can cause the bowls to overflow, which may be the cause of your crappy milage. Ive never seen one of those bypass restrictors fail. What was wrong with it that caused you to bypass it? Did you cap the return line? Or are you running it without the valve?

Sterling

Guys that's not a restrictor, it's a check valve.

The restrictor is the tiny orifice drilled into the side of the hollow threaded tube that holds the inlet and return plumbing to the carb. It's Nikki's (Hitachi's) answer to fuel pressure regulation.
The check valve keeps expanding fuel vapors in the tank from causing the fuel to be pressurized back into the carb should the fuel tank fuel vapor "catching" system fail. (Some people have problems and experience a release of pressure when opening the fuel cap ..."Whoosh". This would cause the carb to hemmorage like a shot pig if it was not for the check valve stopping that incoming pressure.)

...I think you may have the valve in backwards if that is in fact your problem at all. Generally, installing the valve backwards would be like dead-heading your carburetor, which can be done successfully with a new rebuild (strong needle & seat sealing), but the problem is that the checkvalve does allow additional varying tank pressure to enter the carburetor through the return line.
I realize it's damn cold where you are, and it sounds like a warm wheather issue, but fuel vapor is funky stuff. Even if it's cold out and the fuel warms up just a few degrees, I would think (maybe) tank pressures may well exceed 5 psi).
The fact that you can even start it sounds to me that it's possible that the fuel delivery system works just fine when everything has equaled out pressure wise.

bbmac

well so far the valves I replaced were not installed backwards, they just wouldn't let enough fuel through to the return line. the fuel is coming through the float bowl air vent tubes. My guess is float misalignment. we will see what happens as I am rebuilding my secondary carb this weekend. Also I wil put the valve back in and hope for the best I guess. Thanks for all the help!

Sterling

Is your floatbowl vent solenoid hooked up?

It's the valve in the primary side of the carb with a single black and white wire hanging out of it.
It springs closed with no power, and with power, an electromagnet pulls back a plunger and your carb is allowed to vent.