yetterben

Ok lets start with the Pro's first

Car runs like a bat out of hell running from meatloaf!!!
Starts great,Idles great. Has great low-mid-high response.
No bucking of any sorts.

All and all it just drives great, no complaint's

The bad side.

I put 20 bucks in the other day. Gas in Wi is like 3.15 a gallon so i got about 5 gallons for that price.

Drove it to work and back like a normal adult with one instance of running the gears up to 7 grand threw 3rd.

Today i looked down and i am sitting almost on empty. Check milleage 19 on the odo. Now i know rotarys will suck it down my 88 tII got like 20 at its best. But i dunno whats going on.

Mods include RB header. Rats nest removed. Stock nikki for carb. Timming is stock i belive havent ever checked. For that fact i am highly confused on the timing of the rotary and need to work on that. 2.5 exhaust all the way back to one magnaflow i am useing for pre-silencer continues to pass though can with 2.5 inch tail. Any ideas here guys??? Like i said she moves like a raped ape

Thanks in advance and Happy Thanksgiving to all.

Rx-7Doctor

iTrader: (13)

Are you saying that you got just over 3 MPG? $20 would be a little over 6 gallons.

Sounds like you have a fuel sending unit problem which is not all uncommon.

yetterben

I know thats what it seems like. But when my gauge first hits the red zone on my gauge meaning the first hash mark, if you know what i mean my fuel pump makes a diffrent noise and shortly there after it dies. So it dosn't even go down to the dead end of the gauge just the first part of the line. i dunno whats going on but i have purposly run my tank empty to find where the gauge is when my fuel pump starts to make that noise. Standar for me so i know my gauge. 20 bucks got me a little over a 1/4 tank almost to a half i guess on the gauge.

Rx-7Doctor

iTrader: (13)

On your model there is a low level fuel light that comes on when there is approx 2.2-2.6 gallons of fuel left in the tank.

The only way you could actually be getting that bad of mileage is if it was leaking out.
I don't know what the fuel pump situation is but I do not believe that it is operating properly.
The only way to find out is when you supposedly run out that you open up the drain plug for the fuel tank and measure the amount of fuel that comes out.
I am going to bet that you still have 4 or more gallons of fuel left.

yetterben

Fuel light has never come on for me. Fuel pump is new carter. I will have to do some pokeing around back there. When the the needle goes that low i can here the pump run dry. makes a very diffrent whirring sound. inlet for pump is hooked directly to the tank line and sent to fuel line for up front. i just left the stocker in underthre along with that other block with the lines in it. Buy the way what is that other block. Guess i will take it to work and put it on the hoist and poke around. But any other thoughts you might have would be great. Thanks Doc


*edit* Also i should say this is all in town stop and go driving.

Also i still have ?'s as the if my motor is ported or not. Other members have tried explaing to me how to check this but whilest i am very rotary inclined it has only been with stock rotarys. All i know is it has much much much more power than the previous known stock 12a's i have driven.

Rx-7Doctor

iTrader: (13)

If the light has never come on then you probably have never been that low on fuel. This is assuming that the low level portion of the sender is still operating.
Are you running the carter pump through the stock pump?

yetterben

i dont belive so. I think i was at first till i sorced the line back to the tank. And if i am i am pushing threw it not oulling but i dont think i am not 100 percent sure though will have to look. But if i was i would think performance would be really shitty. under the car there is a cube block next to the drivers side tire. and one in the middle of the car right in front of the axle. all have lines. so i know the one buy the tire is the stocker but am not certain what the other one is.
once again i really want to extend my gratitude for your input

Rx-7Doctor

iTrader: (13)

No problem. While you have her in the air could you take pictures of the two cube boxes and the fuel pump and how the fuel hoses are routed.

One of those cube blocks as you describe it is the fuel cut valve which prevents fuel from coming out of the tank in case the vehicle rolls over. That should be the one near the stock fuel filter location nearest the driver side rear tire.

yetterben

If you could take a pic or find on of where the stocker is that would rock cause i never really new where it was. i just found the line that was comeing from the tank and plumbed in mine.

TurboMazdaSpeed

welcome to owning a rx7.. mine was like that.. now i have a microtech ecu.. loaded up a cruising map and gas milage= up! =)


for you i would change the fuel pump sock, take out the fuel filter and blow through it to see if its clogged, if it is get a new one, change your air filter, spark plugs etc. (all the small things) ditch the cat if you have one , and drive in the power band. should make your gas milage go way up.

oh yeah , and buy a narrowband sensor, they arnt very accurate but if you can use them to get good milage (watch them) i did that before i got my MT

yetterben

First off thanks for the replay. I have a 12a so a microtech ecu would be useless. And narrowband are about useless as well. I have done all the little things and am looking for a bigger reason for my issue and maybe like the doc said sender issue but something is wrong thats for sure

TurboMazdaSpeed

aah true that, well defenatly check your fuel filter, mine was clogged and when i changed it it made a BIG diffrence!

kenn_chan

cube shaped boxes with line going in????? sound slike the rear splitter block for the brake lines

quick Doc, help him.

kenn

tallbozo

iTrader: (5)

Yeah my gage says 1/2 tank after driving 30 miles, but then stays there till about 150 miles then follows down normally. Strange beast of mine...

yetterben

trochoid

iTrader: (6)

Something doesn't sound right here. If the engne performs as well as you say, then the fuel filters are good and the exhaust doesn't sound like it could be plugged. It may be running rich and you may have a gas leak somewhere.

I can get 20-24 mpg even with a 1/2 bp on the widebody, driving on the highway at the speed limit, steady state. I've also gotten as low as 8.5 mpg when I had the Mikuni on it it during the winter with long warmups and driveing in city traffic.

To check your true fuel mileage, fill it up and keep track of the mileage and fuel useage, then let us know what your getting. A well tuned 12A, driven in an 'adult' manner can achieve near 30 mpg on the highway and the low 20's in the city.

Have you noticed any raw gas smells? When I first put the widebody together, I was smelling gas occasionally and finally noticed a spot under the rear of the car. Turned out the fuel tank was leaking at seam between the upper and lower halves of the tank

You may wish to look over all of your fuel lines and check the accellerator pump on the carb too for leaks..