Revoroller

iTrader: (9)

Alright so since about October I've been getting absolute shitty mileage in my car. Originally I was getting almost 280mi out of a full tank of 91, and it dropped extremely once fall started...first I was getting about 200mi to a tank and then it slowly dwindled to about 150mi and then to 125mi and last week all I got out of a full tank was 80mi and that was driving like a grandma everywhere! I drove to school which is maybe 3mi and according to my fuel gauge I burnt an 8th of a tank. And then I filled up yesterday and I burnt a 1/4 tank in 22mi. This is just absolute bullshit. So I'm hoping someone can help me.

I've replaced the plugs with new NGK TR55's, replaced the coils and wires, and replaced the 02 sensors and replaced the fuel filter. The only thing I'm left with is if my sending unit is bad and giving me a bad reading... However when I filled up yesterday I was almost on E and I put ten gallons in and it said I was full...and the fuel tank is like 16gallons in LS fbodies right? This is whats making me believe its my fuel pump assembly.

My engine has about 6k on it since being built last spring. All thats done for performance stuff is a TR220 Cam and Typhoon intake with full bolt ons and as said before I was getting really great mileage throughout the summer. And I ONLY use 91 octane fuel and usually only go to one gas station but since the issues started showing up I started trying other stations and no luck so far.

Mako77

Should be able to do the math with the mileage and gallons used to determine the accuracy I would think. Could also have some to do with seasonal fuel blends.

CamaroSS27

iTrader: (6)

I think gas tank depends on year because I think mine is 14 gallons. Check your injectors?

Revoroller

iTrader: (9)

Just learned after 98 they went to composite tanks which are 16.8 gallons. My car is a 99. And I've ran a few bottles of injector cleaner through it, it doesn't cut out and seems to have good power. Whats the best way to clean the injectors?

Revoroller

iTrader: (9)

This was my Dad's thoughts, cause this summer when I first got my engine built I ran out what was left of the 85octane and it burnt through it just as fast as it seems to right now with 91...So I'm wondering if the fuel may be the issue. Back in Dec. I had filled up and got about 220mi out of 3/4 tank and then an injector o ring got torn during install and let go while cruising,so I never got a chance to finish out the tank. I've heard great things about Torco fuel additives from the guys over at TrueStreetCars.com and a bunch of vette guys use it with 91 to make 103 octane incase they can't get it anywhere or something. Anyways they all had succesful results and someone had posted test results of 91 with the Torco additive and it actually worked. I was considering trying it but at $20 a quart its spendy