Slash

DNO IF THREAD IN RIGHT SPOT
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When the gas tank is completely full the gauge only reads 3/4th full. and it does move so it's not stuck or anything, it's like it's timing or w/e is off.
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so as u can guess when the car gets down to reading near empty you can't help not to get edgy(even tho in retrospect theres 1/4th tank). After a bit it jus gets sketchy reading empty yet still goin u dno when u'l run out.
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Would this mean i need a new fuel sending unit/guage or what idk much when it comes to this particular stuff.

Slash

bump

pendragon618

My GTA is doing the same thing.... did you find the cause?

1991z28camaro

iTrader: (3)

I am having the same prob, but mine stay's on full .

f-bodymikey

Mine bounces around but seems to read pretty good though. I have no clue how to fix it though.

matthufham

iTrader: (5)

mine goes over full, and when empty reads 1/4... why? 3 possibilities. inaccurate gauge, inaccurate float/sending unit, resistance in the wire from the sending unit. it's not the most precise combination of parts, but it's close so i just got used to it.

M20

I have this same problem in my 89' firebird. Mine started when me and my mechanic took off the cluster to get to some wiring behind them. It was perfect when we took it off. When we put it back on however it read 3/4 when I had just drove in from the gas station. I just use the trip odometer on mine. MY car gets about 220 miles to the tank. I mean you can still use the fuel guage as long as you know how far it is off. I wouldnt really worry about it.

Slash

nah i havn't found the problem yet, but then again i havn't had much time to work on the iroc yet, it's too cold up here in new york to start sitting out inthe garage to work in the garage, not to mention car is not registered yet so i can't bring it to school garage yet. Getting the Car registered in march so soon to be able to start.
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and yes it can be either gauge, fuel sending unit.

Dno if i could get used to it but worst comes to worst i'll have to. jus hope it's a easy fix.

midnit

It could be as simple as improving the ground.

1983Chimaera

The bouncing problem stems from GM being too cheap to install a baffle around the pickup/sending unit in the tanks. So as you go down the road, accel or decel, the fuel level sloshes around and gives an inaccurate reading. My neighbor had an 87 TBI 305 with the factory tank that would constantly bounce from near full to near empty just maintaining 70 mph on level road. My 83 Z/28 originally had a 4BBL carb 305, and now has a 331ci TPI, still using the original tank and pickup/sensor unit (with an external mounted MSD 2225 inline electric high flow fuel pump), and it doesn't bounce like his did, so there is no rhyme or reason to it. Mine does deviate badly under accel or decel tho as the fuel level sloshes around. If I could figure out a way to install a baffle around the unit like my 94 Mustang has I know it would solve the issue (and works handily as a safety "reserve" to keep from running the fuel pump dry on an EFI system).

jeremymsl

Am i the only one like this? my guage reads pretty normal (i mean it bounces around ALOT but when i cruse for awhile it levels to correct) But what worries me is if i SLAM on the gas even for just a few seconds when it goes back down it reads WAY lower than it did befor!!! I cant tell so is me slamming on the gas really using like a whole gallon or more of fuel for just a few seconds?!?!?!?! please tell me im not the only one like this ??

camaroman91

Mine does that too, I mean I know im not getting that good of mileage but it can't be that bad lol. my problem is that my guage shows a different level when driving than it does parked so which do I trust?

jeremymsl

i trust my crusing speed, like after you get up to 50 then dont slow down just stay steady, that always seems to be the best, parked is right after you brake wich brings the guage down ya know? But so yours will go down by like an 8th of a tank than where it was befor after you floor it to? so its not using that much the guage is just wrong right haha? im like really worried about that haha XD

camaroman91

I like that cause thats the higher of the 2 lol, but yea mine drops about that much after WOT, Its scary cause I know it can't be using that much gas lol

jeremymsl

Whew I'm just glad cause that means I'm not the only one and it is just the gauge XD, dose yours hi back after a day or 2 out dose it just go thru the rest of the tank that much lower? I dint know cause I only floor it when I'm almost out of gas so I'm just like **** it I'm about to be out anyways XD

excessiveego

mine reads normal until you hit about half a tank, then it reads really high (around 3/4) then once you shut it off and restart it it will start reading normal and jump around just alittle until empty..... and im talking electronic problems, not just fuel slosh

camaroman91

Yea I do the same thing, I go easy on it until I'm almost outta gas anyways lol. but I'm not sure about mine though. How much does it actually cost to fill out tanks up? Cause it seems like no matter how much gas I put in it it always goes to 3/4 but then after I start driving and go a couple of miles it shows like 1/4 less than before

drknow90rs_ss@y

iTrader: (3)

This is such a common prob with our cars. Only way to fix it most of the time is to replace the sender. Not cheap, either!

MNformula350

iTrader: (2)

I have the Exact same issue with my Formula, Gauge only Reading 3/4 when Full. Just started doing that one day

So I also Just Use my Trip Odoemter, and my Formula also gets about 220 per tank.

MNformula350

iTrader: (2)

Or Fun

Last time I had the Gas Tank out of the Car, I worked at a GM Dealership, so had all the lifts and tools etc... and it was still a pain.

Convoy25

iTrader: (3)

with the tank dropped its a good time to paint the rear end if its not already

Slash

lol wow ya'll brought back like my first ever thread i made >.>
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Still never had time or money to fix this yet. I just been filling up often guessing how much I've used lol

Gen3-91

They bounce around because the sending units bad on the fuel pump; out comes the rear to drop the Gas tank. and might as well replace the fuel pump while you have it out dont want to do have to drop that thing twice i promise you that. And there is a possibility that the gauge is no longer good(slim to none)

Slash

My problem wasn't it bouncing around.
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Its reading 1/4full when it was actually almost a full tank. So once i droped below 3/4 of a tank left.. it would read the tank was empty. ect. Idk why they went off topic on that o.O

travis401

iTrader: (1)

There is an alternative to replacing the sending unit (if your guage doesnt read or doesnt read full when it is). It does required dropping the tank and pulling the sending unit out though.

If you look at the attatched image, there is a spot circled in red. Its the fuel level reader. Usually the contact or contact strip inside gets corroded or stuck or basically doesnt move like it should. You can pop this peice open and clean it off, it just requires bending the tiny little tabs holding the 2 peices together and cleaning everything out with some alcohol and a brush. Just dont use anything too stiff or you might destroy the contact strip.

Not saying this will solve every fuel level issue, but you can atleast clean this off and then hook the unit back to the wiring harness outside the tank to test if the sender is bad or not. You can manually manipulate the fuel float while someone watches the gauge in the car.

dredre08

iTrader: (2)

Sorry posted in wrong forum

B_Dubya

How about just running your tank with octane booster and premium gas.. think that would help clean up the inside?