I had a question about air fuel for an 87 na.
If you adjust the variable resistor screw besides the pressure sensor all the way to the left, could that give you poor gas mileage?
I know it'll make you run a little rich, but could it make the fuel pressure too high.
I'm not sure if thats whats giving me poor gas mileage. I already did a search, and did not find answers to these specific things I am asking.
Thanks.

 

No, that variable resistor only affects your mixture at idle. Your poor gas mileage is being affected by something else. Whats your current mileage?

 

a full tank only got me like 180 something? not sure, i'll try to get more definate numbers.

 

Checked the o2 sensor lately? Changed the intank fuel filter? Out of tank one? Is your TPS set? Whatabout a clogged cat? check these things first then go from there, vacume leaks...ect..

 

Alright, thanks for the help. But you guys are pretty sure that setting my variable resistor won't lean out my mixture just a little, and restore som e of that gas mileage?

 

It only effects idle as J-rat stated....Also check for leaky injectors...

 

ok, when I have time hopefully this weekend or next, I'll try checking these things. Until then, where should the variable resistor be set. I know it barely turns like 270 degrees from left to right with a screwdriver, kinda like 3/4 a full circle. Wheres the ideal place to set it? Right in the middle, like not to rich, not too lean, or a little rich, or a little lean?

 

Well, unfortunately its not that easy. That resistor screw, along with timing and the air mix screw, all determine idle speed. And to go into specifics about it would take all day. For a quick setting, just move the screw till the idle smooths out. BTW, make sure your ISC connector is jumpered or your wasting your time.

Got an idea. Download the FSM from www.FC3s.org . 4A or 4B depending on your model has all the information on this procedure.

-J-

 

Alright. So i finally got around to changing the fuel filter, the one under the hood, yet i can still smell fuel when i turn the car on and drive. I am going to change the o2 sensor next. Hopefully that will be the end of my poor gas mileage. If not, and i still smell gas, I will try to check out those fuel injectors for faulty gaskets, and what not. I doubt that the fuel lines would have any leaks, but you never know. Has anyone ever had a leak in their fuel lines before? If so, how did you go about fixing it?

 

wait going to what J-rat said, what is the ISC connector and where is it at?

 

Gas smell? Check out the pulsation dampner attached to the secondary fuel rail immediately. They are known to fail, leak, and due to the location of the secondary rail, the leaked gas can flow to the exhaust manifold and you can kiss your car goodbye.

Next up would be the o-rings on the injectors themselves.

Is your charcoal canister (near the pass fender/firewall) still connected?

 

Are you suppose to fix or replace the pulsation damper?

 

Some people have used "fixes", generally you just replace it if it's leaking.

 

Is it a part that is availible through your neighborhood auto parts store or do you need to yank it from another car from the junkyard or something?

 

Goddamn, I called mazdamasters today, and they said it would cost about $400 dollars in the end including parts and laborto fix the pulsation damper. Thats way too damn much.

 

Labor?

rofl.

Download the FSM from www.fc3s.org and do the work for free.

 

After installing a new fuel filter, there is a difference. I'm getting about 15 mpg. Thats better but still not good. I can swear I smelled gas from near the passengerside rear, below the gas lid. Where do you guys recommend getting your rotaries serviced, because I think I want this problem diagnosed.