Jkkiller

I am 17 I am a Jr mechanic I've been working on cars sense I was able to turn a wrench but I'm having a problem with my 1994 trans am that I just can't figure out
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Here's my problem i will be driving my trans am and all of a sudden back firing and no power sometimes no power steering aswell ( bc car shut off ) this happenedsite normally near empty ( on gas) and the first time this happened I thought it was because I put engine cleaner in the gas tank and I didn't have enough gas but it happened again and I am still dumbfounded about why the second time the car was harder to start than before both times happened at around 50 to 55 mph and once it happens I can't do 45mph without it back firing and dieing on me

frankzlt1

You want to check your fuel pump pressure. Also you say it's happening when your fuel level is low but not out fuel you may have a fuel pickup problem in the tank.

Injuneer

The fuel gauge calibration is terrible in these cars. When the gauge indicates "1/4" you may have as little as one gallon. Run the tank dry and it can damage the pump.

Info from Shoebox:

4th Gen LT1 F-body Tech Articles

The "F-Body Lounge" isn't the best place for tech help. I'll move this to a more active forum.

Jkkiller

What do u mean by fuel pick up problem ....like the fuEl pump has gone our or going out....... but would no fuel cause the backfire

bw_hunter

It will back fire if it loses fuel and then gets fuel.its a classic running out of fuel scenario in these cars. Fill the tank and let us know if the problem recurs....

Jkkiller

Also if it is the fuel gage calibration Is of how would I go about recalibrating it

Jkkiller

The 1stime time it happened I filled it drove it close to home once I was close I punched the gas ( to see if it will happen again after filling up ) nothing I got the car to 90 no problem

bw_hunter

You really can't...it's just something to live with. I guess you could put a resistor in line to change the range but I'm not sure. Fuel up when you reach 1/4 tank and you'll be OK.

Jkkiller

Thanks bc that is where is happened both times at almost exactly 1/4 tank

DanPlaysZ28

In my 95 Z28 my fuel gauge is off a good bit so 1/4 tank is actually the empty line, sounds like you may have that problem

Injuneer

Normal

Shoebox - Fuel Gauge

The problem can be even worse if someone has removed the gauge needles to install a dash overlay.

gaedbo

I know a lot of people probably wouldn't purchase the same fuel pump that I did for various reasons, but I did it anyhow. My fuel gauge didn't work. So I purchased a Spectra SP3908H Fuel Pump Assembly (Entire Fuel Pump, everything included) from RockAuto for about $120, and installed it about a year ago.

They claim it to be accurate on fuel level. Exact fit, looked like a quality assembly to me, even though I wasn't paying big bucks for it. (Only issue was the large "O"ring at the top was wrong diameter, so I had to use the one from the one I removed). Mine is very accurate, full, 3/4, 1/2, 1/4 , all really close to what it is supposed to be.

So either I got real lucky, or they figured out how to do it right.

Anyhow, just thought I would throw this in there, in case some one doesn't need a high performance fuel pump like me, or needs to fix their fuel gauge issue.

Chimera96

short of replacing the entire FP assembly in the tank with a new "good" one (debatable which new brand that is)...this link shows a guy "gently" repairing his unit to get the fuel gauge to read like new

How to refurbish your fuel sending unit - Chevy Impala SS Forum

There are some, me, who put in a adjustable resistor inline to "trick" the gauge to read right. It does now...but FWIW if you are down to 1/4 tank get gas. You really want to keep the FP submerged (cooling) anyway. Yeah the tank is baffled around the FP which should keep it always submerged in gas but that baffling is somewhat compromised with a low tank and hitting corners. Ever hit a fwy big curve on ramp with heavy gas pedal and low tank and had the motor stumble....that is the FP sucking air

Injuneer

Problem is restoring the float sensor to "read like new" means it reads exactly like the screwed up calibration numbers shown in Shoebox's write up. We bought our cars brand new, and we both had the same calibration issues from day-1. The gauge was always wrong.

After about a dozen tanks of gas, I came up with a chart similar to Rob's. I could predict my MPG because the 1/2 mark meant I had consumed exactly 10 gallons of gas. Only 5.5 gallons left. My 1/4 mark meant less than 2 gallons left.

Been responding to this question online for 20 years on sites like this, and it's always been the same. To me, once I knew how many gallons were left at each hash mark for my specific vehicle, that was all I needed. Just lived with it.

Jkkiller

Ok thanks for helping me out guys but I have a couple of other problems we not really problems but questions my window won't roll down or up I had to pull up the window by hand and roll the window up while holding the window does that mean the motor is shot bc I still hear it when it activated but won't roll the window