Horrible fuel economy with my 93 vert, is there something wrong with my gauge?

[Clark W. Griswald]

I filled up the tank yesterday and after driving about 40 miles tops I'm at 3/4 of a tank. I went through a quarter tank of gas I'm less than 50 miles? I havent been driving balls out or anything and last night it seemed to be at 3/4 of a tank after just 27 miles. Its now at approx. 40 miles and its a hair under 3/4. Is the sensor in the tank just finnicky, is it the gauge, or are these cars really that much of a pig? By the way its all stock exept for a K&N filter. Thanks.

[wmdavis007]

hmm...not sure. I check my MPG about every other tank of gas and I get 29-31 MPG every time...and that's city miles. Maybe your sending unit got stuck or something. I would fill it back up and keep an eye on it. Hopefully it's nothing serious. Oh yeah...I do run premium (93 octane), that's what Nissan suggests, so that's what I run.

[mmm240]

You shouldn't judge by the gauge.

Next time you fill up make a note of your mileage (or reset your tripometer) then drive at least 100 miles. Fill up again and divide your tripometer (or subtract what your odometer says now from when you filled up) with the amount of fuel you alloted and you get your mileage.

[94_240sx]

That's not right. I think you should fill it up again after you drive 27 miles and see how much gas takes to fill her up. If not much, yes sending unit is possibly bad. There's this floaty thing goes up and down in the gas tank and it could have gone bad. First, see if you actually use that much gas or not.

[Clark W. Griswald]

What I did in my Cressida was fill it up and reset the tripometer. Then when it got to empy(light came on) Id divide how many miles I got by how many gallons the tank held. I just dont want the gauge to be off and I run out of gas. If the sending unit is bad, wouldnt I be starving for fuel or is that mainly up to the pump?

Also, whats the gallon capacity of the fuel tank and how hard is it to replace the sending unit, or that floaty thing? Should I go ahead and replace the fuel pump while Im at it if I do have to go in there? Thanks

[mmm240]

Don't divide by what the manual says the tank holds. Divide by what you allot. Only then can you know the actual mileage of the vehicle. Get back to us after you know this fact.

[wmdavis007]

Drive your car until your gas gets low. Fill up your gas tank. After filling up the tank zero your tripometer, run that tank of gas down low again. Re-fill your tank...make sure this time you get the gallons of gas you added and divide those gallons by the miles on your tripometer and that is your avg. miles per gallon. Simple.

As for the sending unit, it won't starve your engine for gas...you are correct, it's up to the fuel pump. Replacing them both is pretty straight forward...pretty simple and yes I would replace the pump while your replacing the sending unit.

Just fyi...91-94 s13 KA24DE gas tank holds 60 liters or 15 7/8 gallons.

[Azrial]

sounds to me like the thing on the fuel pump that tells your car how much gas is in it. My gas gauge is messed up to. It only fills to 3/4 of a tank generally sometimes it will finally find it's way up to full. There is a part on the fuel pump that floats as the gas rises. If you search the technical forum you should find pictures. It's probably gotten dirty or something or it has fallen off. That happens to from what I've read. I just haven't brought myself to endure the fuel smell long enough to figure out what's wrong with mine since it works fairly closely I have let it go.

[-RJ-]

i had that problem with my s14, i just put a full tank and drove 200 miles and refilled

[Clark W. Griswald]

Im hoping all it is is the bouy on the fuel pump. I'm gonna make sure my tire pressure is good, and I don't have a slight exhaust leak(my car has a little to throaty of an exhaust note I think), and of course calulate the mpg with the formula you guys gave me. I've had the car a few days and I've already got a long list of things to do to it...here we go again. Thanks for the help, and Ill let you guys know.

[Azrial]

Just keep us updated we are always here

[Clark W. Griswald]

Today I replaced my spark plugs, recharged the K$N filter, and cleaned my throttle body to see if that helps. Unfortunately my car wont start after I disconnected the battery fir an hour...

By the way, please check out my thread on this, I need help badly. Cheers.

[Clark W. Griswald]

Well after speaking to a very nice lady in the parts dept. at the dealership my next step is to check the fuel sending unit float for a rupture. Id like to buy another fuel sending unit flat out if they werent so hard to find so it looks like ill be checking to see if thie float i have holds liquid or not. Then ill have to find a solid way to keep it sealed up.