IrocZ85

iTrader: (10)

Well guys I bought a 89 Iroc 350 auto not to long ago. Gas Gauge doesnt work though. It sits way past full at all times. I have changed the gauge and it just reads as full as it will go. Wondering if anyone has had this problem and knows what to look at. If you dont know which they are the color wires coming off the fuel tank wiring is appreciated to try and find were the problem is currently, but again any knowledge or help with fixing or diagnosing this is helpful, thanks in advance.

John in RI

iTrader: (167)

Sounds like a break in the wiring or connection somewhere. If you disconnect the plug from a the gas tank wiring with a working set-up,... the gas gauge floats all the way UP.

Your issue could be the wiring at the fuel tank pick-up, along the harness to the cluster, or the printed circuit on the cluster itself.

84redta

iTrader: (34)

purple wire coming from the sending unit to my knowledge. I think it's 0 to 90 Ohms??? Can't remember but 0 is empty.

Tan is the pump and black is the ground. Make sure the ground is good on the pump harness.

IrocZ85

iTrader: (10)

Thanks for your help guys fuel gauge now fixed as off today 3/16/08

TF34MECHH

I have the same problem. What did you do to fix it? The schematic shows a ground (G304)
for the sender and shows it being on rear seat bracket. I dont have any grounds there.
Thanks
Shawn

IrocZ85

iTrader: (10)

Well I ended up actually having to change my sending unit as it was real rusty from someone changing the fuel pump and forgetting to re-install the o-ring seal

For you though I think your talking about were the wires ground out under the driverside rear seat, if your car is really rusty you might just need to change the ground to a seperate location (i suggest the seat belt bolts as they make great grounds and are hidden), That would at least be were I would start and hope this helps you

TF34MECHH

Thanks for your help. I pulled the seats and could not find any grounds. Does anyone have a pic of this ground under the back seat?
Thanks

FirenScuba

see my gauge works interminently where is teh ground for the sender because that will be my first spot to look.

84redta

iTrader: (34)

three wires coming from the sending unit, tan/white stripe (power for the fuel pump), purple (power for the fuel level float to tell how much fuel you have), and black that grounds both out, you would not have fuel pump to my knowledge if you don't have fuel guage. But tracing that black wire would put you coming into the body behind the rear seats under the carpet.

84redta

iTrader: (34)

just went out and checked, there is this block looking thing that is bolted to the axle hump underneath the carpet behind the rear seats. 3 wires (described above) come from the sending unit, into a plug, plug is attatched to said rivited box, box is rivited to other side of sheet metal inside the car bringing 3 wires in, purple and tan/white stripe (described above) come in and go down driver side rocker with all the other wires of the car, while the black wire grounds out to the rear seat bump (you will understand if you remove your rear driver seat), underneath the front of the bottom driver side cusion.

Purple wire should go to guages, and tan/white stripe wire breaks in two (should be under dash area???), one going to the ECU as a signal wire and one going through the firewall to the fuel pump relay in the engine compartment, towards the driver side fender against the firewall.
----------
Also firen scuba, you should check out the link in my signature, we are having a cruise this summer (one of possibly a couple), among dinners and such, you should join!

Denis.V

Hi,

I'm in the same boat with my wife's Corsica.

Black wire is ground for both: fuel level & pump. Then, if you have fuel pressure (fuel pump ON), you have good ground.

Purple wire is positive fuel sender voltage. You can test with a ohmeter at the socket near to the fuel tank (You can know if the problem is IN or OUT of tank).

If you replace the fuel sender unit , be sure to use a 0 - 90 ohms sender (used for GM). Other cars uses 30 - 240, etc (I don't be sure if 0 ohms is empty or full).

Denis V.

First-Timer

i've got a 1990 iroc z and as well my fuel guage isnt working. i dropped a 350 carb motor into it. and this is what i have came up with. i have pulled the tank out and hooked the sending unit up and manually operate the float and my guage wont go past a half tank. when i unplug it from the connector it goes all the way past full. i've tested my sending unit and it passed. Anyone have any ideas what would be causing this? any suggestions would be apppreciated thx jeremy

KITT1983

iTrader: (3)

Any updates on your progress?

undertow310

what did u do to repair your fuel gauge problem im having the same problem and it sucks running out of gas !

thacker85

i got an 82 camaro and the gas gauge points strait up, dome light doesn't turn on, cigarette lighter doesn't work, and the horn doesn't work??

KITT1983

iTrader: (3)

did you check the fuses?

thacker85

Checked them and found one fuse blown an that fixed the dome light and ciggerete lighter. The horn still doesn't work niether the gas gauge and I have checked to see if mayb
e a ground wire was loose or getting a bad connection and it was just fine

P-ROC

iTrader: (2)

Do you have an aftermarket steering wheel? Did you check connections at the horn and at the horn button? When I bought my camaro the horn didn't work because someone removed it and never replaced it.

KITT1983

iTrader: (3)

thats good
my dome light fuse keeps blowing so i keep spares in my trunk.

that 25 amp circuit on my year (1983) provides power to the interior lights, radio, tail lights, parking lights. power trunk release and etc

i am still trying find the source to this dilema.

Is the gas gauge past the "F" Mark? if yes, then you have a bad sending unit.

thacker85

Yah it's way past the F. How bad is it to get to the sending unit? When I changed my fuse I saw that the dome light turned on so I started wondering if it fixed my ciggeret lighter so I pluged it in and it blew the fuse. So mabe try just leaving your ciggeret lighter out to see if it helps

KITT1983

iTrader: (3)

what is the make and model of you KARR? what is the motor ?

as long as you dont have the crossfire injection you are golden

do you have a console light ? are there any metal fragments in the ciggarete lighter?

you could have a short somewhere.

blueguy10168

Most likely a short if fuse keeps blowing. that was the case back when I had my S10. The radio,horn, and dome light were on the same fuse so when I hit the horn, the dome light would come on!

I just got my 85 camaro back from the shop. They said I need a new instrument cluster. The signal is fine from the sender all the way to the dash until the connector where the wire goes in. I've dropped in another needle and it does the same thing. sits at 3 o clock or bounces around everywhere. The question I have is: If I'm going to get another cluster, can I take one from a IROC camaro? I want to have the tach and gauges instead of lights. To those who know the answer, I don't know much about cars, but I'll understand as best I can.

pjams91

so i have an 85 camaro with a manual fuel pump, the fuel gauge isn't working, bought a new one still won't work, when i hook it up it goes straight to F maybe a little past when i disconnect the ground. I tested the sending wire and ground for OHMS, the circuit said i had around 27.7 ohms which is a little over 2 gallons which is what i knew was in there. so why does my gauge go to full when i hook it up when i can read ohms with multimeter?

KITT1983

iTrader: (3)

your the fuel tank sending unit is bad

Legit Echo Shot

ok im having the same prob but i do know that my sending unit is bad i just dont know where to look for one if you have any ideas please let me know thanks you

Loess Hills

I have a 90 RS i bought as a shell,put a 350 carb set up in it,it didn't have a fuel tank in it so I found a fuel tank out of a 83 and used it.I cut the lead off of a 90 fuel tank and hooked up the wires to the 83 fuel tank.the gauge does not lift off of E.the computer is not in the car either,is it necessary for the gauge to work.

travis401

iTrader: (1)

dont need the computer for the gauges.

NINÅ

slangdon

My son has a 1986 Camaro Z28. We put in a carb'd 5.7/350. It has a manual fuel pump. Fuel gauge is incorrect. It bounces up and down. I'm sure its the sending unit. However Ilook for a sending unit and its usually for TBI fuel injection. Any suggestions where I can get one for a carb'd manual fuel pump

NINÅ

Camarodude1987

im thinking of ordering a new fuel gauge for my iroc i can order either a 60 ohm or 30ohm gauge, does anyone know how to tell which one I need?

NINÅ

andyvr4

Not true I have a brand new sending unit fuel pump and fuel tank and my gauge also doesn't work.

KITT1983

iTrader: (3)

Is the gauge needle stuck on e ?

andyvr4

The gauge is stuck far past full but it also jumped once to the E and I put more fuel thinking it might be out started it again and jumped back to passed the full mark??

KITT1983

iTrader: (3)

Did you ohm the sender to see if it was defective.

andyvr4

I have not yet but will how should I do it?

KITT1983

iTrader: (3)

do you have a multimeter? a lift or jack stands ?

andyvr4

Yes I do.

bshirley55a

So I need to replace my sending unit. whats the easiest way to get to it? I have heard you have to drop the tank but it appears you would also have to drop the rear end? I have also heard you can pull the carpet up in the back and cut a hole in the trunk pan and get to it?

andyvr4

You cant cut a hole in the trunk won't work cause all the metal tubes from the sending unit follow the top of the tank and curve down the behind the hump of the rear seats it would have to be a big hole and not a circle. its a very simple job just time consuming rear end dropped makes it so... much easier I went to an 89 1le rear when changing fuel sending unit and tank for new so it was easier.

travis401

iTrader: (1)

if Ive said it once Ive said it a thousand times....dropping the tank does not mean you have to drop the rear end. you do have to put the car on stands or a lift and leave the rear unsupported and let it droop. you also have to unbolt and move the exhaust out of the way. you can get it out with some slight bending of the filler neck, or you can cut it and save yourself some hassle. if you look inside the rear wheel well, theres an access panel that opens up tot he filler neck, theres also a spot weld on the filler neck, near the top, where the breather tube is welded inside. you need to cut it at that weld, whic lets you remove the top couple of inches of the filler neck. with those couple of inches removed, the tank has just enough room to slide out. you can rent a chain tubing cutter from autozone, you dont wanna use anything that will cause sparks (obviously). then when you put the tank back in, use a small piece of rubber rose and a couple clamps to reattach the part of the filler you took off.

its a much better solution than cutting a gaping hole in your car.

andyvr4

Cutting the filler neck!! Thats definitely not the correct way and can cause you problems down the road. cutting your filler tube to your gas tank is probably really bad advice it can be done and will probably work but it's definitely not the correct way to do it the correct way is to drop the rear end it takes you maybe 20 to 30 more minutes depending on how confident you are and it gives you so much more room to get tank out I just did it and I am a hundred percent glad that I took the rear end out to get the gas tank I will never cut my gas Fill tube....

travis401

iTrader: (1)

most filler necks these days are mostly rubber with a few pieces of metal on the ends anyway, the spot you cut it is only a few inches down from the top. mines been like that for years now with 0 issues.

andyvr4

No offense doesn't mean its right. But glad no issues for you

powder white

whats the color on the sending unit for fuel on 89 rs 5.0 book says pink
shop book

damaginc

the book says pink but the wire actually looks purple

Sir ian

whenever i hit the brakes the gas gauge goes down
[For example] i can have a full tank i can come to a stop and it will go to a half tank then go back up after i let up, any one know how to fix it?

Mark84

I have an 84 berlinetta. Does my fuel sending unit ground wire go to the same location? Is it inside the car or under the vehicle. My fuel guage is always over full and my address fuel light is always on.

John in RI

iTrader: (167)

Your fuel gauge wire runs from the cluster, to behind the kick panel,.... then it runs under the drivers door sill to the back of the car behind the drivers side rear "glove-box". From there the fuel gauge wire runs thru the tail-light harness, thru a hole in the body, and under the car on the drivers side. If you look under the car on the drivers side rear you will see the wiring & connector pinned to the body and where the wires lead up to the tank pick-up.

FYI: MANY TIMES a Berlinetta fuel gauge problem like you describe ( needle shoots past full / low fuel warning light on ) is caused by a bad Cluster printed circuit. This is not always the case,... but it is common for the printed circuit to fail causing needle gauge and backlighting problems.