I have a 1992 firebird 3.1V v6 fuel injector, anyways, with a Full tank i can go 108 miles til empty, i changed the fuel filter. i should be getting 300 miles on one tank, what else is there to change???????????

 

Is that until you run out of gas, or just when the gauge says it's empty?

 

its til the needle is on the E

 

Where does the needle go to when you fill it up? And does it go down evenly, or not move too much at first but then faster? Just wondering. I'm guessing sender or gauge perhaps?

 

it goes right to Full, and goes down slow, let me tell you this, i changed the fuel filter and i got 50 miles on one full tank of gas, forgot to tighten the fuel lines, was to afriad to tighten them to tight, now its getting 105 miles on a full tank, i heard it could be anything from the O2 sensor to fuel pressure reglu. i just dont want to spend alot of money changing 3 things when all i had to do was change one thing

 

First off, this is the TBI forum . That does not apply to your engine. It's a TPI whose discussion belongs in that forum just above this one.
If your engine was actually using up that much fuel it would show in lots of poor running ways. If your car runs OK, then it's more likely that the parts that say you are out of gas are at fault. Just something to consider...

 

The 3.1l engines are MPFI. The V6 forum further down the board is the one to use.

As for the fuel usage, unless this is due to a leak to the outside, the plugs have to be fouled by now. If the original Multec injectors are still in the engine they are bad and should be replaced.

Pull a few spark plugs and see how they look. If sooty black then the fuel is going through the engine. Suspects would be: injectors, FPR leaking, fuel return and vent lines reversed at fuel tank (sends fuel directly to CCP canister), bad CTS.

dustyknight, welcome to TGO.

RBob.

 

Thanks guys i will check plugs this coming monday if not tomorrow, what is a FPR, and CTS?

 

When you fill up from E, how many gallons does the pump show? The stock tank is 16 gallons, usually 14 is about the max that can be pumped into an almost empty tank.

The fuel gauges in these cars dont exactly read linear. They also tend to get a bit flaky. The gauge might not be reading right. The same applies to the odometer and trip odometer. The point being, verify how far you're actually driving, and how much fuel you're burning.

You wont get 300 miles a tank with a 3.1. Not even on the interstate. They're only rated at 16 city/25 highway in perfect conditions. With today's ethanol fuels you can bank on not hitting those numbers.

 

16 * 25 = 400 miles on a tank. Fixing a few code issues and enabling the lean cruise mode getting over 30 MPG on the highway is typical.

RBob.

 

Just checked the window sticker for a '92 3.1l f-body. EPA average is 18 mpg city and 27 mpg highway. Which makes it easy to approach 400 miles of highway on a tank of fuel.

RBob.

 

Try fueleconomy.gov.

Fixing code issues? I guess I missed where OP is running custom code.

As I mentioned, 16 gallons is the maximum capacity. In the real world you aren't going to get 16 gallons in, and you aren't going to get 16 gallons out. Going on 21 years with these cars. I've run them down to the last drop more than once, but I've never gotten a full 16 gallons in the tank on a fill-up.

Take a 3.1L thirdgen and go try to get remotely close to 400 miles out of a tank. Bring a friend with a trailer or a AAA card, you're going to need it.

Contrary to popular believe, a 140hp V6 in a 3,200lb car with 3.23 gears isn't going to sip gas like a Geo Metro. In practical experience I never noticed much difference in fuel economy between any of my thirdgens, V6, 305 4bbl, TBI, 350 TPI, just didn't matter much.

 

That's funny, it states the same as the window sticker, imagine that.


Now you are just twisting the facts around

And the point is?

I have and didn't need a tow either. Filled up, got on the highway and didn't need fuel for 440 miles. Tank took 13.2 gallons to fill (you do the math...). Like I said, a few code changes and enabling the lean cruise mode does that trick.

Now lets go back to the stock code. EPA rated highway is an average of 27 MPG. So lets leave a gallon in the tank, 15 gallons times 27 MPG = 405 miles.

Getting 300 miles out of a tank of gas is easy. The worst of your posting is that they aren't helping the OP at all. Nada, none, along with your incorrect information.

RBob.

 

what is a FPR cause if its linking i need to fix it, and what is a CTS??
So the needle must not be working correctly, i guess i would have to change that too

 

FPR is the fuel pressure regulator. It is the dome shaped piece under the plenum on top of the fuel rail. It has a diaphragm inside that can tear or get a pin-hole in it.

It has a vacuum line going to it, remove the line from the back of the TB and smell it. If it smells of fuel it is likely leaking.

CTS is the coolant temperature sensor. They usually fail by reporting a lower temperature which causes the ECM to add more fuel to the engine.

> So the needle must not be working correctly

Tank level gas gauge needle? I would start by verifying other items that are on the easier end of the scale. When troubleshooting I eliminate the easy stuff first.

Such as checking some spark plugs. Only takes a couple of minutes and with that will know if the 'lost' fuel is going through the engine or not.

RBob.