About 4 years ago I had the usual Gas Gauge dropping to zero and Techron finally would do no more, so GMPP replaced both sensors as my final warranty claim. All was well until a month ago. I ONLY use Chevron with Techron Premium and always add Techron additive each fill up.

About a month ago I was sitting at a red light with about 11 gallons used in the tank and the gauge just dropped to zero and the Low Fuel warning came on. Tonight, got the same thing at a red light and I was right next to a gas station, so I pulled in and filled up - only took 6.5 gallons this time? So am I looking a new sensors AGAIN.

I can't believe that a 3rd party has not come up with a better solution to this chronic problem! I talk to people with other models of cars all the time and they never have this issue?

 

No, the car has never run out of gas... ever. I usually fill up when it gets just below 1/2 tank. Since tonight the car only took 6.5 gallons to fill, there should have still been fuel in both tanks.

I did hit the reset, but that just dismissed the DIC warning - gauge was still at zero and Range was blank.

 

Have you ever had the ECM reflashed for this issue? There is a TSB from GM that talks about a recalibration flash to help fix the gas gauge going to empty issue.

 

Yes... unless it lost the flash?

 

I agree with 8VETTE7. Sounds like either R&R your right side sender/pump assembly (the orifice) or replace it John.

 

Is the "pump" integrated as part of the "sender" unit?

 

Yes. On the right tank it is. IOW, you can't order just the fuel sender seperately. Same for the siphon-jet section as well.

The left tank is different. There, you can order the fuel level sensor by itself or the entire pump assembly.

The upside, if there is one, is that the right side assembly is much less expensive. Btw, prices have come down quite a bit over the recent years as there is more than one source for this stuff now.

 

Thanks. I think my Warranty Direct PowerShield Enhanced Extended Warranty covers this fix - guess I will get to see if they try to weasel out of it - never filed a claim on it yet!

 

Do you know if a Tech II can test for a bad sensor/jet pump with a full tank of gas or do they have to drain the tank first?

I am trying to figure out if I can make a trip to the shop to diagnose in advance so they can order parts under warranty before I have to take it in for the actual repair since I am sure they will not have the parts locally.

 

Exactly........ That's the way it works. As long as he has a non-FFS fuel system car (mid-'03 or '04) this can be done with tank still in car as you say. I also think using Techron at each and every fill-up is massive overkill.

 

My understanding is that this can be tested with a Tech II (or multimeter) by monitoring the fuel sender voltages from each tank and noting whether the left tank stays mostly full (not all the way, I dont know the exact value) while the right tank is at a lower level. I would suggest about half total fuel.

 

I have a 2001 coupe, but the last time they replaced the sensors in both tanks, they did not have to drop the tanks - just the shields and they removed the sensors from the lower portion of each tank - took about 2 hours.

 

I used to have a problem with the faulty gas gauge as well. It was intermittant. Sometimes I would be 3/4 of a tank and it would drop to 1/4 of a tank. Sometimes it would fix itself. Techron always worked. After a couple of years of this, we moved to another part of the city where I began refueling at a different gas station. Never had the problem again and no need to use Techron.
Try changing gas stations before you go to the trouble of replacing pumps and whatnot.

 

I admit I am a bit stumped. I understand if the right tank were acting up how I would get the Low Fuel warning at close to 1/2 tank level. But night before last I was only down 6.5 gallons from being topped off when I got the warning? Would that not be a problem in the left tank as well?

 

Have you seen this thread? It will help a lot.

http://forums.corvetteforum.com/c5-t...m-failure.html

 

If the PCM senses the absence of transfer, after a certain distance driven, it will drive the gauge to zero and give a low fuel message as a warning. I believe the reflash discussed earlier increases the distance before the warning. The true test of an inop transfer is if you run out of fuel and it only takes 12 or so gallons. I had this happen to me because I thought it was the typical gauge behavior due to deposits. Wish there was some way to read each tank separately.

 

My eyes are burning... just read that entire thread!

So... as I understand, if the computer senses that there is more fuel in the right tank than the left tank while the car is running, the fuel gauge will drop to zero. There are two primary ways that this usually occurs...

(1) The jet pump venturi is clogged or not functioning in the right tank. (no/reduced flow occurs from right to left)
(2) The right tank sensor is reporting the fuel level incorrectly - corroded. (flow may be occurring, but computer does not know that)

Since both of the above items are part of the same assembly, replacing with a new assembly will probably solve either/both issues for a while.

If (1) is the problem - the tank has to be drained and the venturi cleaned or replaced. If (2) is the problem Techron/Seafoam "may" remedy the issue or at least keep it at bay. The frustrating part is that there is no way to know which issue is causing the problem ahead of time unless the engine actually dies - in which case it was probably (1).

Of course all of this is assuming that the left tank sensor is reporting correctly, but that does not seem to be mentioned as often as failing - probably since it is always submerged in fuel - while the right sensor can be exposed to air/gasses whenever gas gauge nears/goes below 1/2 tank.


I am not showing any codes when I run diagnostics

 

Just pulled codes again - I see a History Code now of PCM 1431. I think that is the right sender?

 

Yes. According to the service manual: This diagnostic tests for a stuck right fuel level sensor signal. If the PCM determines that the right fuel level signal appears to be stuck based on a lack of signal variation expected during normal operation this DTC sets.

 

So I guess it could still be the sensor or the Jet Pump?