Fuel Level Gauge

[SunlitComet]

So you are still getting pressure. Does your security light go on with the key out and go off when key is turned to run position but not started?

 

[L8RH8R]

Still getting pressure. The security light DOES NOT go on when the key is out but DOES go on when the key is turned to the run position but not running.

 

[SunlitComet]

You will have to check for spark then. the passlock will disable fuel pump if something is wrong. This is what should happen exactly:

During normal operation, the SECURITY light will go
off approximately five seconds after the key is turned to
the RUN ignition position.

The only thing that comes to mind is the fuel flow is being block somewhere but if you put on a gauge and see at least 42 or more you should be started. Perhaps try starting for a bit and see if the computer has failed a sensor with a rescan after trying several times. But don't kill the battery.

 

[gpracer1]

I bought my 99 Tahoe (OBS) approximately two months ago. The fuel level gauge moved back and forth (millimeter) so fast it was an orange blur and not consistent. I replaced the gauge cluster and that DID NOT fix the problem. I recently replaced the entire fuel sending unit with a new Delphi unit and now the truck won't start and the fuel gauge remains inaccurate. I checked the fuel pressure and it ranges from 48 to 50 psi. According to the Chilton book this is normal (low end). I'm going to put the old unit back in and that should solve the issue of the vehicle not running, but what about the fuel level gauge. Any suggestions. Thanks.

How do you know that the (I assume used) cluster didnt also have a bad fuel gauge?

 

[L8RH8R]

How do you know that the (I assume used) cluster didnt also have a bad fuel gauge?

I don't. It was from a 99 Escalade. I do have access to two other gauge clusters and am going to swap them in to see what happens. The odds of all three being bad should be slim to none. I will post and let you know. If this does not do it, I will check the ground wire, although it is secure and the wiring is intact and coated.

 

[AtomicHoe094]

Kinda off subject. I grabbed a 99 escalade cluster for my truck, and previously the truck gauge was fine. After the swap the gauge went nuts moving back and fourth. So i pulled that cluster out and switched the stepper motors and waaaalaa.

Also ive heard the movement of the needle can be a ground issue. not sure if thats your case but check the wires.

 

[L8RH8R]

Well I put the old sending unit back in and whatdaya know, it cranked right up. I then swapped out the gauge cluster with two other vehicles and the problem persists. My friend told me it is still most likely the sending unit and advised to ground out the sending unit wire and if it pegs the fuel gauge, the sending unit is the problem. I've pretty much ruled out the ground wire. My thought is if that were the problem the pump would not function properly, or at all since they are grounded at the same point. Is this flawed thinking? On another note, I have read about the stepper motors in the gauge cluster. Are these difficult to replace. I've seen them on ebay. Again thanks for all the input. Little things that don't function as they are intended drive me nuts.

---------- Post added at 10:31 PM ---------- Previous post was at 09:47 PM ----------

Atomic, I just disassembled the old cluster to check out the stepper motors. It appears the fuel gauge had little to no physical resistance when moved by hand and the others were more fluid. These all appear to be the same so tomorrow I will transplant one into my gauge cluster. I'll keep ya posted. Thanks for the path.