HELP. Fuel guage malfunction
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 906
Likes: 2
From: The Woodlands TX
HELP. Fuel guage malfunction
Ok so we replaced the intake pump with an aftermarket pump on my 06 ZO6. Everything works fine except the fuel gauge. WHen the car is filled up with fuel it only reads 3/4 tank. As it goes down it will hit the 1/2 -1/3 mark and immediatley go to empty with a service fuel system warning. I can reset it with HP tuners but then it will only go to 1/4 tank and no farther. Has anyone had this problem? Any suggestions? The car only has 25K miles on it. Thanks in advance.
Last edited by flyinmedic; Jul 17, 2011 at 07:43 PM.
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,954
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
I'm guessing the crossover pipe isn't seated properly. I'm not the tank expert so someone else needs to chime in on this one.
Elmer
Elmer
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
I'm going to state the obvious....you mucked up something with the driver's side tank fuel sending unit when the new pump went in. The Vette has two fuel sending units, one in each tank. It expects the driver's side sending unit to read full until the passenger side tank empties and the passenger side sending unit shows the tank is empty. When the car reads 1/2 full your driver's side tank is full and the passenger side tank is empty.
Any combination of gauge readings other than the scenario above results in the "service fuel system" generic message. Typically there are other error codes you'll get pointing to the fuel sending unit error in the tank.
Sounds like you'll get to drop that tank again and recheck all of your work.
Any combination of gauge readings other than the scenario above results in the "service fuel system" generic message. Typically there are other error codes you'll get pointing to the fuel sending unit error in the tank.
Sounds like you'll get to drop that tank again and recheck all of your work.
Track Junky
Joined: Jun 2007
Posts: 4,074
Likes: 36
From: Orlando Area
Tech Contributor
Motorhead, I replaced my fuel pump with a walbro 255 unit and will be firing up the car for the first time later this week. The pump assembly came out a bit rough from the tank, but everything looked intact upon inspection. With regard to your statement above, would any of us see visible damage to the sending unit for the above symptoms, or is it internal damage? I even went so far to clean the wipe pattern with alcohol to be sure I wouldn't have issues.
Any history or personal experience may help someone attempt to diagnose the problem flyinmedic is having. Specifically, what could or should he be looking for if he drops the tank again?
Any history or personal experience may help someone attempt to diagnose the problem flyinmedic is having. Specifically, what could or should he be looking for if he drops the tank again?
Instructor
Joined: Jan 2010
Posts: 157
Likes: 0
From: Deerfield Beach Florida
it is next to impossible to get the fuel float hooked up to the sending unit on install when changing pumps. the pump measures close to the 4" hole it goes into, you need hemoststats like a surgeon would use during a heart transplant to try to snap the float properly into the sending unit. even experts have trouble with this one
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
Motorhead, I replaced my fuel pump with a walbro 255 unit and will be firing up the car for the first time later this week. The pump assembly came out a bit rough from the tank, but everything looked intact upon inspection. With regard to your statement above, would any of us see visible damage to the sending unit for the above symptoms, or is it internal damage? I even went so far to clean the wipe pattern with alcohol to be sure I wouldn't have issues.
Any history or personal experience may help someone attempt to diagnose the problem flyinmedic is having. Specifically, what could or should he be looking for if he drops the tank again?
Any history or personal experience may help someone attempt to diagnose the problem flyinmedic is having. Specifically, what could or should he be looking for if he drops the tank again?
I've seen a post some time ago that tells us what values should be on those two terminals when the tank is full and when the tank is empty. If we had those you could ohm out the connector while everything is still in the car and then you'd know for sure. Let me browse and see if I can find them.
Last edited by Motorhead-47; Jul 18, 2011 at 06:53 PM.
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 906
Likes: 2
From: The Woodlands TX
Not knowing exactly what his replacement consisted of it is sort of hard to tell. There are 4 wires in the plug on the OEM pump. The two smaller gauge green wires are the fuel sending unit. If either of those two were damaged or if a terminal backed out of the harness on install (I've had this happen when I plugged that connector in on the bottom of the flange) then you'll get some very strange readings. I'd start with verifying that those wires are firmly inserted in the connector. Unfortunately that connection is on the bottom side of the flange.
I've seen a post some time ago that tells us what values should be on those two terminals when the tank is full and when the tank is empty. If we had those you could ohm out the connector while everything is still in the car and then you'd know for sure. Let me browse and see if I can find them.
I've seen a post some time ago that tells us what values should be on those two terminals when the tank is full and when the tank is empty. If we had those you could ohm out the connector while everything is still in the car and then you'd know for sure. Let me browse and see if I can find them.
Thank you for the info, it would be great if you find those readings. The setup is an Aeomotive A1000 in tank pump and a DP 2000hp external pump. When the car is almost empty it will take over 13-14 gallons so hopefully it's something simple.
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
Out of my service manual....
Resistance
• Empty tank reading 247-253 ohms resistance
• Full tank reading 38.5-41.05 ohms resistance
I have not installed an A1000 but I believe it uses the stock fuel sending unit so those values should be good. The connector I spoke about above is NA in this case.
Resistance
• Empty tank reading 247-253 ohms resistance
• Full tank reading 38.5-41.05 ohms resistance
I have not installed an A1000 but I believe it uses the stock fuel sending unit so those values should be good. The connector I spoke about above is NA in this case.
Last edited by Motorhead-47; Jul 18, 2011 at 09:52 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 906
Likes: 2
From: The Woodlands TX
Out of my service manual....
Resistance
• Empty tank reading 247-253 ohms resistance
• Full tank reading 38.5-41.05 ohms resistance
I have not installed an A1000 but I believe it uses the stock fuel sending unit so those values should be good. The connector I spoke about above is NA in this case.
Resistance
• Empty tank reading 247-253 ohms resistance
• Full tank reading 38.5-41.05 ohms resistance
I have not installed an A1000 but I believe it uses the stock fuel sending unit so those values should be good. The connector I spoke about above is NA in this case.
Le Mans Master
Joined: Dec 2004
Posts: 5,492
Likes: 808
From: West coast CA
On the OP's '06 car, each sender should read 40 empty and 250 full.
To make certain that the float lever isn't hung up on anything after you've completely reassembled a tank, verify 40 ohms resistance with the tank right side up. Then hold it upside-down and check that the resistance has gone to 250.
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
GM inverted the sender's range in '07 or '08 so that a poor connection would cause the gauge to err on the empty side rather than full.
On the OP's '06 car, each sender should read 40 empty and 250 full.
To make certain that the float lever isn't hung up on anything after you've completely reassembled a tank, verify 40 ohms resistance with the tank right side up. Then hold it upside-down and check that the resistance has gone to 250.
On the OP's '06 car, each sender should read 40 empty and 250 full.
To make certain that the float lever isn't hung up on anything after you've completely reassembled a tank, verify 40 ohms resistance with the tank right side up. Then hold it upside-down and check that the resistance has gone to 250.
Question: If you walk into the dealership to buy a replacement fuel level sending unit for an earlier model car do you walk out the door with one that reads 40 empty and 250 full or 250 empty and 40 full?