Fuel gauge....drops to empty tank
#1
Fuel gauge....drops to empty tank
I've been reading many posts on this issue and thought I'd share my experience and provide a progress report on the solutions/trouble shooting that I'm going to employ after reading all of the posts here on Corvette Forum about this issue.
I bought my 02 C5 used and like many that have had this problem my fuel gauge would drop to empty when there was at least 3/4 of a tank at the time. The "Check Gauges" dummy light would go on at the same time. I took it to the independent dealer for other small issues and they were scratching their head because the fuel gauge had started to read as it should. Therefore they couldn't figure it out.
Finally after this cycle repeated itself several times I did the self diagnostic check trick on the DIC (Driver Information Center) and received the "P1431 H" code which is fuel level sensor 2. The dealer performed the same diagnostic check using their professional equipment and got the same code and stated that both fuel pump modules be replaced.......to the tune of $2,100.- Mainly because there is a lot of labor involved in reaching these modules I guess.
I opted for them not to perform this repair.....just yet. I was going to give the remedy that everyone on this forum tried successfully before I plunked down that money or asked the dealer I bought the car from to pony up and fix the car I bought from them.
So when my fuel gauge was reading a little less than 1/4 tank (when it started working again) I added a bottle of Techron to the tank then filled it up. Less than a 1/4 tank of miles in to the new tank of gas the gauge dropped to zero again. Judging by the miles I had traveled on this tank so far I'm projecting the gauge will start to read normally again very soon...when it reaches about 1/2 tank or less in reality.
On my next fill up I'll add a second bottle of Techron for the second cycle of this treatment. I'll keep you all posted as I hope some of you will benefit from this saga.
Fingers crossed!
I bought my 02 C5 used and like many that have had this problem my fuel gauge would drop to empty when there was at least 3/4 of a tank at the time. The "Check Gauges" dummy light would go on at the same time. I took it to the independent dealer for other small issues and they were scratching their head because the fuel gauge had started to read as it should. Therefore they couldn't figure it out.
Finally after this cycle repeated itself several times I did the self diagnostic check trick on the DIC (Driver Information Center) and received the "P1431 H" code which is fuel level sensor 2. The dealer performed the same diagnostic check using their professional equipment and got the same code and stated that both fuel pump modules be replaced.......to the tune of $2,100.- Mainly because there is a lot of labor involved in reaching these modules I guess.
I opted for them not to perform this repair.....just yet. I was going to give the remedy that everyone on this forum tried successfully before I plunked down that money or asked the dealer I bought the car from to pony up and fix the car I bought from them.
So when my fuel gauge was reading a little less than 1/4 tank (when it started working again) I added a bottle of Techron to the tank then filled it up. Less than a 1/4 tank of miles in to the new tank of gas the gauge dropped to zero again. Judging by the miles I had traveled on this tank so far I'm projecting the gauge will start to read normally again very soon...when it reaches about 1/2 tank or less in reality.
On my next fill up I'll add a second bottle of Techron for the second cycle of this treatment. I'll keep you all posted as I hope some of you will benefit from this saga.
Fingers crossed!
#2
8Vette7
Good to know my friend! I'll will keep this in mind if Techron doesn't do the trick. I'm pretty mechanically inclined and the way you describe this repair it doesn't sound like it's beyond the skill level of a do-it-yourselfer. I'll hit you up in the future (if you don't mind) if my dilemma comes to this point.
Thanks again!
Good to know my friend! I'll will keep this in mind if Techron doesn't do the trick. I'm pretty mechanically inclined and the way you describe this repair it doesn't sound like it's beyond the skill level of a do-it-yourselfer. I'll hit you up in the future (if you don't mind) if my dilemma comes to this point.
Thanks again!
#3
I had it happen to me for the first time today as well, after 3 months of ownership.
30K on the odometer. It happened after an hour of highway driving....just boom.....check gauges light...then showing an empty tank (it was 3/4 full.)
I'd been planning to do the Techron trick anyway, as when I fill up, the gauge shows between full and 3/4.
oh....and 5 minutes after stopping, I restarted the car and everything worked perfectly.
30K on the odometer. It happened after an hour of highway driving....just boom.....check gauges light...then showing an empty tank (it was 3/4 full.)
I'd been planning to do the Techron trick anyway, as when I fill up, the gauge shows between full and 3/4.
oh....and 5 minutes after stopping, I restarted the car and everything worked perfectly.
Last edited by Red Square; 09-23-2017 at 06:43 PM.
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Ram907 (02-29-2020)
#4
Le Mans Master
I had it happen to me for the first time today as well, after 3 months of ownership.
30K on the odometer. It happened after an hour of highway driving....just boom.....check gauges light...then showing an empty tank (it was 3/4 full.)
I'd been planning to do the Techron trick anyway, as when I fill up, the gauge shows between full and 3/4.
oh....and 5 minutes after stopping, I restarted the car and everything worked perfectly.
30K on the odometer. It happened after an hour of highway driving....just boom.....check gauges light...then showing an empty tank (it was 3/4 full.)
I'd been planning to do the Techron trick anyway, as when I fill up, the gauge shows between full and 3/4.
oh....and 5 minutes after stopping, I restarted the car and everything worked perfectly.
The following 2 users liked this post by JR-01:
bravo29 (09-26-2017),
Mikegerm_C5 (09-23-2017)
#5
Advanced
I have this problem about once a year and normally Techron takes care of it after one or two treatments. I just had this happen and like the OP, put I put in the Techron and filled up, got down to just under 1/2 tank and the fuel gauge functioned again. What I learned from this thread that I haven't seen is that filling up the tank again can cause the sensor to stop working again - more crud on that part of the sensor element apparently. I will soon be filling up and adding another bottle of Techron. Well see what happens. Yes 20 oz bottles.
#6
Melting Slicks
After reading in here, I used 12 oz. of Techron complete fuel system treatment, poured into a near empty tank. Filled it up and it's been fine for over 3 months. I now stock (on sale) Techron, as the recommend was bi-monthly. Guess I'm just lucky with Costco fills.
Last edited by whalepirot; 09-23-2017 at 09:11 PM.
#7
Melting Slicks
I had the fuel gauge issue common to any of us C5 owners. Regular treatments of Techron and use of only Shell premium solved my issue. No repeat problem for quite a while now since starting the Techron/Shell regimen. Best wishes!
#8
Originally Posted by 8VETTE7
ABSOLUTE AND TOTAL RIPOFF on an 02 to replace both sensors.
You have to expect that from a STEALERSHIP especially after they applied the CORVETTE TAX.
Here is a picture of the fuel tanks for the C5 BEFORE mid model year 2003:
Attachment 48209220
Attachment 48209221
As you can see there are access panels on the back side of each tank and behind the one on the right tank is the sensor and jet siphon pump (all one assembly) that corresponds to the P1431 code that you have. With the tanks below half tank the access panel for the passenger side tank can be removed with minimal fuel spillage and the tanks DO NOT have to be removed from the car for this repair. Many Forum members have done the replacement of this sensor and jet siphon pump in their garage. Parts cost are well under $200 for the passenger side and labor is at most a couple hours for a DIY person and half that at a shop that has lifts.
If it were my car I would run half a dozen tanks of fuel with the Techron Plus Concentrate added just as you described before I would even consider replacing the sensor and there is no need with the one code you have to replace the drivers side sensor.
For those reading this thread that have the 2003 with a build date after November 2002 or any 2004, the tanks are redesigned and you MUST drop the tanks to access the sensors or fuel pump. The effort to do that is far greater and might warrant paying a shop to do the replacement. Here are the tanks in the late year 2003 and all year 2004 C5's:
Attachment 48209224
As you can see the only access to components inside the tank is from the top of the tank so tanks MUST come out for repair on a C5 with the FFS fuel system pictured...
You have to expect that from a STEALERSHIP especially after they applied the CORVETTE TAX.
Here is a picture of the fuel tanks for the C5 BEFORE mid model year 2003:
Attachment 48209220
Attachment 48209221
As you can see there are access panels on the back side of each tank and behind the one on the right tank is the sensor and jet siphon pump (all one assembly) that corresponds to the P1431 code that you have. With the tanks below half tank the access panel for the passenger side tank can be removed with minimal fuel spillage and the tanks DO NOT have to be removed from the car for this repair. Many Forum members have done the replacement of this sensor and jet siphon pump in their garage. Parts cost are well under $200 for the passenger side and labor is at most a couple hours for a DIY person and half that at a shop that has lifts.
If it were my car I would run half a dozen tanks of fuel with the Techron Plus Concentrate added just as you described before I would even consider replacing the sensor and there is no need with the one code you have to replace the drivers side sensor.
For those reading this thread that have the 2003 with a build date after November 2002 or any 2004, the tanks are redesigned and you MUST drop the tanks to access the sensors or fuel pump. The effort to do that is far greater and might warrant paying a shop to do the replacement. Here are the tanks in the late year 2003 and all year 2004 C5's:
Attachment 48209224
As you can see the only access to components inside the tank is from the top of the tank so tanks MUST come out for repair on a C5 with the FFS fuel system pictured...
#9
You need to look at the codes that is set. The Thread starter had P1431 which is for the sensor in the passenger tank. There is ALSO a code for the sensor in the drivers side tank when it is not responding as the PCM expects.
Keep in mind that the way the fuel tanks in the C5 work is that the electric pump in the drivers tank feeds the engine and also delivers a small stream of gas to the jet siphon pump in the passenger tank that results in fuel from the passenger tank being siphoned into the drivers side tank. The result is that the passenger tank empties first and then the drivers side tank empties. The PCM is expecting this and calculates the level of fuel remaining based on expected operation. The PCM sends the calculated fuel level to the IPC to display on the gauge via a message across the serial data buss. Once the passenger tank is empty (based on voltage measurements that the PCM sees from the passenger tank sensor) it would calculate the fuel level based on the readings from the drivers tank sensor. So I would not necessarily expect issues once the fuel level reaches 1/2, unless the drivers tank sensor was corroded as well.
One noteable event that this causes is for the passenger tank sensor to be left exposed to the air for much longer than the drivers tank sensor. This might exacerbate the build up of oxidation on the passenger tank sensor....
Keep in mind that the way the fuel tanks in the C5 work is that the electric pump in the drivers tank feeds the engine and also delivers a small stream of gas to the jet siphon pump in the passenger tank that results in fuel from the passenger tank being siphoned into the drivers side tank. The result is that the passenger tank empties first and then the drivers side tank empties. The PCM is expecting this and calculates the level of fuel remaining based on expected operation. The PCM sends the calculated fuel level to the IPC to display on the gauge via a message across the serial data buss. Once the passenger tank is empty (based on voltage measurements that the PCM sees from the passenger tank sensor) it would calculate the fuel level based on the readings from the drivers tank sensor. So I would not necessarily expect issues once the fuel level reaches 1/2, unless the drivers tank sensor was corroded as well.
One noteable event that this causes is for the passenger tank sensor to be left exposed to the air for much longer than the drivers tank sensor. This might exacerbate the build up of oxidation on the passenger tank sensor....
You might be on to something....about the passenger side sitting exposed to air, etc. I'll have to go back and look at the codes concerning the gas tank modules to see if it reflects anything about the driver's side tank.
I also think it might be possible this car sat idle for a long time based on it's mileage (26K when I bought it), the condition of the car; it had a rough surface on the paint that made me think it was exposed to the elements for a long time to the point the paint was covered in a layer of dust, etc.....I have since clay barred it back in to good condition. One of the other repairs that have been done was a short in a wiring harness....it was probably old and brittle. The cowels were full of debris causing water to collect which killed the wiper motor...and that had to be replaced.
All good info to think about here.
Thanks again!
#10
Melting Slicks
The Techron is the way to go with this problem with the gas gage. I've had this problem and it helps. I use nothing but Costco fuel that has addictives added to the fuel at the pump and have not had a problem for years. Use a fuel that has the Techron added if you can. Be patient, it should help over time.
Last edited by Fcar 98; 09-24-2017 at 10:02 AM.
#11
Le Mans Master
If Techron does not do it, you might try this. It freed mine up when Techron quit having an effect...
#12
Melting Slicks
Member Since: Nov 2014
Location: Havre de Grace Maryland
Posts: 3,133
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My gas regiment: Fill with top quality gas only, Shell preferred. Never let gas level fall below ¼ (usually fill when gas gauge falls below ½.) Add Techron every other tank fall. After 3 years of ownership, no fuel gauge issues so far.
#13
Burning Brakes
Any information on removing the sending unit when Techron does not help and the needle remains on E. When I bought my 99 FRC the gage stopped working. Fed it some Techron and the gage started working but now it has quit again and Techron is not helping. Thanks
Last edited by 64Corvette; 09-24-2017 at 02:52 PM.
#15
Burning Brakes
I got gas!
Try running the codes from the buttons on the the dash and then reset them. My gage has been setting on E for the last 5 months. I just ran and reset my codes and the gage is working fine now. For how long only time will tell. As much Techron I have been running through the tanks the contacts shoud be sparkling clean!
Try running the codes from the buttons on the the dash and then reset them. My gage has been setting on E for the last 5 months. I just ran and reset my codes and the gage is working fine now. For how long only time will tell. As much Techron I have been running through the tanks the contacts shoud be sparkling clean!
Last edited by 64Corvette; 09-24-2017 at 08:35 PM.
#16
I had a funny experience today. On Saturday I was cruising on the expressway, the tank just reached a little under the halfway point. All of a sudden the fuel gauge dropped to empty, the "check gauges" warning came on and also the low fuel warning. So on Sunday I purchased some Techron Plus; added it to the tank and was planning to head up to the local Shell station to fill up, I figured it should be at the quarter full mark. After starting up The fuel gauge still showed on empty; I gave her a light rub on the console and said what a pretty girl she was and the gauge jumped up to the quarter full mark. Hmmm, maybe a few kind words help too. So she got a tummy full of Shell V-Power, a wash and wax and I'm keeping my fingers crossed.
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Ram907 (02-29-2020)
#17
Burning Brakes
I took your advise and ran the codes and one code said that # 2 tank sensor was not responding. There were a couple of other codes that showed up as history. So we went back through the codes and reset each code that popped up with a message. When finished the gas gage was working like it should. So it may be a good idea to check your codes and then try re-setting the codes. I now have a working gage, red check engine light out, and no more be bells ringing! Thank you sir for your suggestion!
#18
Le Mans Master
I took your advise and ran the codes and one code said that # 2 tank sensor was not responding. There were a couple of other codes that showed up as history. So we went back through the codes and reset each code that popped up with a message. When finished the gas gage was working like it should. So it may be a good idea to check your codes and then try re-setting the codes. I now have a working gage, red check engine light out, and no more be bells ringing! Thank you sir for your suggestion!
#19
Instructor
"P" on it, I've been driving with a messed up guage for over 6 years now, when it zero's out and my Light comes on I hit the Reset and drive on and ignore it. Every fill up I zero out the odometer and refill @ 300 miles or so. I've never had one stinking problem and normally the guage corrects itself at about the halfway mark after the car's parked for a bit.
Worry and fuss over more important crap than this.
But, if you have any mechanical skills the fix is as easy as they come, I've just been too lazy and cheap to do it (about $400 for the right tank and maybe $250 or so for the left)...BTW, I am way past mechanically inclined (licensed A&P for 30 years or so and twisting wrenches for near 50), but like I said, it's a piddly problem and I'm lazy and cheap about this thing
Worry and fuss over more important crap than this.
But, if you have any mechanical skills the fix is as easy as they come, I've just been too lazy and cheap to do it (about $400 for the right tank and maybe $250 or so for the left)...BTW, I am way past mechanically inclined (licensed A&P for 30 years or so and twisting wrenches for near 50), but like I said, it's a piddly problem and I'm lazy and cheap about this thing
#20
Le Mans Master
"P" on it, I've been driving with a messed up guage for over 6 years now, when it zero's out and my Light comes on I hit the Reset and drive on and ignore it. Every fill up I zero out the odometer and refill @ 300 miles or so. I've never had one stinking problem and normally the guage corrects itself at about the halfway mark after the car's parked for a bit.
Worry and fuss over more important crap than this.
But, if you have any mechanical skills the fix is as easy as they come, I've just been too lazy and cheap to do it (about $400 for the right tank and maybe $250 or so for the left)...BTW, I am way past mechanically inclined (licensed A&P for 30 years or so and twisting wrenches for near 50), but like I said, it's a piddly problem and I'm lazy and cheap about this thing
Worry and fuss over more important crap than this.
But, if you have any mechanical skills the fix is as easy as they come, I've just been too lazy and cheap to do it (about $400 for the right tank and maybe $250 or so for the left)...BTW, I am way past mechanically inclined (licensed A&P for 30 years or so and twisting wrenches for near 50), but like I said, it's a piddly problem and I'm lazy and cheap about this thing
Last edited by JR-01; 09-24-2017 at 09:22 PM.