Hello,

I recently installed a new fuel pump in my Camaro, the fuel pump seems to be working well. The problem is with the gauge.

There was this really janky looking ground connection on the sending unit, inside the tank that I removed when installing the new pump.

I removed this because I thought the ground from the connector under the car was the only one I needed, and it tested out correctly.

It looked like the tank and fuel pump have been switched out before.

Anyways, the fuel gauge, and to a lesser extent, the voltage gauge do not read accurately.

The fuel gauge "floats" is the best way to describe it. When riding sometimes it will place itself at a seemingly accurate position, other times it might appear full.

My question is, was the ground inside the tank required? Or do I have a loose wire/ground somewhere else?

Also the voltage gauge seems to bounce from 13 to 8 or so randomly. While I have my live data logging going, the voltage maintains itself pretty consistently.

I know for a fact that I need to replace the instrument cluster circuit board. First time I had it out, it looked pretty shoddy, and now the light for the left hand blinker doesn't work.

I can recall the gauge worked semi properly before the pump swap.

Any ideas?

I've heard there is a ground somewhere under the rear driver side seat, but I have never seen a picture of it, does someone have one they can upload? If not, I might try to do so when I try to tackle it later on.

Thanks in advance!

 

Well I ended up buying a new printed circuit board. I will update with results when it comes in.

 

I was taking it for a drive after setting the timing, idle, and apparently fixing all the codes... Fingers crossed.

She drove better than I have ever felt.

However, I was doing some break in on the new brakes and when I braked hard, the fuel gauge pinged full. I checked under my rear seats carpeting for any grounds, but all I could find was this pack. I know the fuel system plugs into this from the other side.

However this black tape surely isn't stock, and I am not really looking forward to seeing whats underneath...

 

HeyO! I’m currently dealing with the pegged fuel gauge too. That plug pictured with the tape is in fact the fuel pump and sending unit harness. I bet you anything that that’s going to be where your problem is if there’s tape around it. Someone didn’t spend the time to fix it right.
You'll have to jack up the car and unplug the harness from underneath the car. It’s almost right directly above the differential. Then drill out those rivets from the inside of the car and remove the tape to see if you’ve got a loose connection anywhere.
Purple wire is sending unit, black is ground, and whiteish is fuel pump.
There’s a test you can do by shorting the black and purple together with a paperclip to see if the wiring going to the gauge is good or not. When jumping the two pins, your gauge should jump to full or empty. I’ve also heard there’s wiring under the dash you can check too.

this is where I’ve got to so far. Will do a write up once I figure mine out.

here’s some sources I’ve used

https://www.thirdgen.org/forums/elec...t-working.html

https://www.thirdgen.org/forums/elec...tuck-full.html

 

Fuel Gauge Body Connector Pinout - Third Generation F-Body Message Boards

 

Id look at the gauge at a stop and see how it acts..It should be level a/a not moving around a lot at a stop...if you stop on a hil letc. it will move to a certain point and stop....

The gauges in these and ALL GMs of the era are so inaccurate if you are moving / slowing..... they slosh around like crazy. Or I guess you could argue that they ae super accurate since they move with the gas moving around....

. there are some cars that apparently had baffles in the tank to help prevent this i heard though.

 

Im pretty sure my issue is the sending unit, and will be replacing it this winter. If that doesn't fix it. Well...

 

To keep this explanation as simple as possible...
Modern Vehicles have a Fuel-Level Gauge, that either uses a Buffer to move the Gauge-Needle. or uses a BCM/ PCM to control the Gauge-Needle.

Essentially the Gauge does not react/ respond to the Fuel Tank Float in real time.
The Gauge-Needle will only move if the Float has changed position steadily for 30 to 60 seconds.
This prevents the Gauge-Needle from moving around like a Boat in the Ocean.

 

What about the gauge needle dampening fluid drying out? Is that real?

 

Leaking at least is.

 

Yes, the gauges can have a problem in which they lose the dampening fluid (high viscosity silicone).Whether it dried out
or leaked out, I don't know, but the gas gauge of my 1987 Camaro had that problem. You might be interested in this thread, in which
I explained how I had this fixed:

Fuel gauge successfully redampened -- no more bouncing! - Third Generation F-Body Message Boards

 

Thank you.

 

That looks stock. GM used that duct tape like stuff on many of the harnesses in our cars. There are 3 wires that go through that bulkhead.

Black - Ground
Gray -Power
Purple - Fuel Gage

 

Yes they did... Looks original to me as well.