hello everyone,
here is a scenario and a question for the experts. (please help)

My FX is running find, with the Silvertop 4AGE 20V, but lately it started to starve for fuel when there is at least 2 to 2-1/2 gallons of fuel in the tank.
also, the gages doesn't go all the way to full or empty. only goes to 3/4 of tank for full, and 1/4 of a tank when start starving for fuel.
should I replace the fuel pump and all the components, as well as the sender unit?

one more thing, if anybody knows how to set the proper Air to Fuel ratio at the Air Flow Meter, I will greatly appreciated.
I don't know if I have it tuned right. I am getting a little be of smokey smell inside the cabin, and the chrome pipe is getting black. does anyone knows where do I connect a multimeter or how to tune the AFM?

Thank you

Sounds to me like your engine might be getting too much fuel rather than not enough.
Black tailpipe indicates running rich. The AFM is factory calibrated and sealed. It is not
meant to be user adjustable despite what the internet will tell you. If the AFM looks
like it has been pried open then a previous owner may have messed with it, but if it
is still sealed leave it alone.

Check your engine water temperature sensor first before you do anything else. If the
engine runs fine under load (accelerating uphill) then the fuel pump is doing its job.
And there is a DIY somewhere for cleaning the contact surface in the fuel level sensor,
and that usually fixes the problem of not indicating full range.

Cheers... jondee86

BlueAngel wrote:hello everyone,
here is a scenario and a question for the experts. (please help)

My FX is running find, with the Silvertop 4AGE 20V, but lately it started to starve for fuel when there is at least 2 to 2-1/2 gallons of fuel in the tank.
also, the gages doesn't go all the way to full or empty. only goes to 3/4 of tank for full, and 1/4 of a tank when start starving for fuel.
should I replace the fuel pump and all the components, as well as the sender unit?

one more thing, if anybody knows how to set the proper Air to Fuel ratio at the Air Flow Meter, I will greatly appreciated.
I don't know if I have it tuned right. I am getting a little be of smokey smell inside the cabin, and the chrome pipe is getting black. does anyone knows where do I connect a multimeter or how to tune the AFM?

Thank you

I had to use a AFR meter I got from auto zone (hooked it into the test port)

but I was able to get my 85 MR2 to pass CO emissions

the adj screw only works at idle

This is how the factory AFM works on a stock AE86...



Can't say if the 20V AFM is exactly the same though.

Cheers... jondee86

Looking at the beginning of this post.

Does it run good until the fuel tank gets low?

Possibly, the fuel pump popped out of it's bracket or whoever got in the tank could have bent the bracket.

Just throwing it out there.

Another thought that comes to mind. If the engine is in fact running rich rather than lean,
is to check if the vacuum line running to the fuel pressure regulator has become split or
been accidentally disconnected ? If it has, then the engine will run rich at idle but should
run clean under high rpm and load (WOT conditions).

Cheers... jondee86

Jondee thanks for that factory AFM adjustment info. Mine has the seal broken. I will check the distance to the screw top. I suspect I'm running a bit rich.