I got an 02 z06 and the gas gauge has been very erratic, dropping to e sometimes and coming back up....any idea what this could be?

 

it's the sending unit in the LHS tank 90% of the time

 

Yeah. It's probably the sender in the tank, sulfur deposits tend to make it not work ! Seems to be a common problem with the C5. My '98 coupe did the same thing, then quit all together. The fix, in my case, was the "Techron treatment". Run the tank as empty as you can safely, then pour in 2 bottles and let it sit overnight, fill up the next morning. It took twice for it to losen mine up, but, has been just fine for quite awhile now.

 

one more question - my gas tank wont fill to capacity (i get about 14-15 gal of capacity when the manual says 18.5)...would this also be the same problem?

 

NO,,,It isnt!!! The right hand tank has a siphon jet in it that siphons fuel OUT of the right hand tank into the left hand (drivers) tank. Your siphon system is not functioning or is clogged. You should drive the tank as near to empty as possible and then remove the fuel pick up and metering assy from the tank. BE CAREFUL! That tank will be near 3/4 full.

Very carefully look for the clog and remove it. The hole in the siphon is very small so the trash will also be small. While it is out, inspect the fuel level assy and make sure that there are not any deposits on the electrical contact board or the wiping arm.

BC

 

Might throwing a can of BG-44K in it loosen things up?

 

Has anyone ever tried cleaning the sending unit? I would like to try that before spending the $$$ if it's a possibility

 

I've been battling the faulty gauge/fuel sender since last winter..
My final fix is replacing the fuel sender all together (waiting for its arrival). I did 'te Techron' to the tune of four bottles, I pulled it out and cleaned the venturi orifice (that hole is impossibly small) using compressed air and again with a needle. I even went to my favorite stealership for some "professional help" but knew that was a waste when the mechanic told me he couldn't access the fuel sender 'cuz he "couldn't drop the tank far enough" (wtf???).

Sooo, I am replacing it altogether.
Good luck with your repairs.

 

do you have any pics? I never had the tanks out and I am planning on replacing my sender

 

Yes, I have a couple of my C5's by cleaning the sending unit; I have zero experience with the siphon valve over on the RHS tank.

 

lemme look, I think I do. I'll have to e-mail them to you, I'm not a "supporting member" and therefore can't upload pics to the forum.

 

could be the case on the NEWER late2003/2004 systems

 

armycop,

Which sender are you replacing - LH , RH, or both?

Also, does the gas tank have to be removed to get to the senders?

 

I'm replacing the pass. side sender on my 2001. I've heard that 2003 and up might be mounted from the top of the tank, but that would mean a design change to the sending unit/fuel system. Let's be clear here, there is only ONE sending unit; the fuel pump is located in the driver's side tank, and no, you don't need to drop either tank in a 2001 to access the pump and sending unit. Access to the sending unit is accomplished by dropping the RR tire, removing the shield, and undoing the seven 7mm bolts holding the unit in place. My replacement is in transit; once I'm ready to replace, I'll take lots o' pictures.

I replaced the fuel pump last year. Not hard to do for either.

 

A couple of bottles of Techron every oil change will head-off these issues!

 

Guys:

I have a 98 with the same problem. Can I access the sending unit without taking the tank down?

Thanks

 

1997 to early 2003 fuel tanks all can be sending unit serviced in place. The sending unit/pump is on the lower aft end of the tank and easily accessed. Male sure that you collect and analize the DTCs prior to repair. The DTCs will tell you which sender is causing the issue (drivers, passengers or BOTH.)

Make sure that you run the fuel out of the tank also.

BC

 

Bill:

Thanks for the reply. What do you mean by DTC's? Is this the computer readout?
Thanks a bunch

Dave

 

This:

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!

 

they are here at my photobucket page:http://s646.photobucket.com/albums/u...fuel%20sender/

I've replaced the sender twice now, pump once. Going through my second bottle of Techron this week, and I STILL HAVE A F**KED GAUGE!! Gonna burn this wreck to the ground and buy a Porsche...