I've been working on my 90 240sx, replaced a lot of parts ($600 worth) and finally got it running good. My problem is now that everything seems to be running good, I'm only getting 10 mpg. I had a full tank of gas and only got 160 miles out of it. Any ideas on what it might be?

Here's the specs and what I've done so far:

90 240sx KA24E SOHC 5spd
I dropped it 1.9"F/1.7"R ebay springs
Modified sleepy eye headlights with driving lights
all new fluids (oil change, tranny fluid, diff fluid, topped off the antifreeze and ps fluid)
new air filter
new fuel filter
new MAS
new TPS
new fuel injectors and seals(all 4!!!)
new fuel pressure regulator
new cap, rotor, and plugs
new Oxygen O2 Sensor
new Coolant Temp Sensor
new pcv valve
new Intake Hose (old one was cracked)
Timing set at 15* BTDC
I even replaced the muffler and cat (not new but good)
cleaned all connections on everything (lots of corroded connectors)
checked AAI valve (clean and functional)
checked IAV (clean and functional)
EGR is functioning properly
no gas leaks, no funny smells, no weird noises...

I cant figure out whats causing the poor MPG...

Engine Compression is 150 psi +/- variance between cylinder less than 6psi
I back-probed the O2 sensor and am getting .835volts +/- a few milivolts at idle (running rich)
CEL is off, no stored codes in ECU

This car is driving me crazy... all I wanted was a gas saving daily driver :banghead: :screwy: :shakehead

did you replace all the fuel filters or just the engine bay one? i would check the in tank fuel filter, or any others that there are on a 240.

maybe you have a hole in your gas tank, happened to a friend

Gonna sound stupid too but make sure that the fuel line going to the fuel filter isnt cracked and leaking... I had a cracked fuel line that had never been replaced and before I fixed the line I got only about 225, after I changed the $3 line, Im getting 380.

i've looked and looked... no leaks at all... not even a slight smell of gas... I think its just running rich. Timing is set right, all the sensors and other components are either new or working... im stummped! :screwy:

could be the ecu

I think its fixed... it was on empty so I put $10 of gas into it (3 gallons here in CA.) then drove it around town on running errands and got 60 miles out of it driving like a grandma. I figure 20 mpg around town is about right? On the previous tank of gas I didn't account for all the times i let it idle, all the high revs, and all the pedal to the floor moments. aside from that, it was already less than a half tank when I changed out the temp sensor which I think was one of the main problems from the start along with the pressure regulator. So I guess its fixed, now I need to align it and change 2 tires. :screwy:

Thanks for all the help guys! :grinyes: