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#1 |
Registered User
Join Date: Dec 2006
Location: Wesley Chapel, Florida
Posts: 1,113
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Fuel Guage help
Last weekend I found the break in the wire that caused the fuel guage to go past E i.e. no resistance. Spliced the wire back together and connected the tan wire into the fuse block. Now the guage stays on empty after putting about 5 gal in the tank. I started tracing that same tan wire from where I found the break to the back along the frame rail. I could not find anywhere it was grounding out, but I could only go to where the wire went over the top of the tank. I could not reach in between the blazer tank and bottom of the bed to where it connects to the sending unit. Anyone know how to check the wiring or the fuel sending unit without dropping the tank? I want to check of the wire is grounding out or if the sending unit is bad, but I can't get to it. Any ideas?
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2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer |
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#2 |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
Posts: 2,692
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Re: Fuel Guage help
IIRC, 0% resistance (completed circuit) would cause the guage to go to full, actually past full. If you take the the tan wire and ground it out anywhere along the frame it should move the needle to full if everything is working right. When it was broke in two, (100% resistance) It caused the needle to go to empty.
So I would ground out the tan wire as close to the tank as possible and if the guage goes to full it is your sending unit or a connection right at it, etc. If nothing changes, then you have wire problems farther up the line closer to the guage or the guage itself. I had a similar problem and after trouble shooting I found it was the guage. Changed it and everything worked fine. Hope this helps.
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72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#3 | |
I'm a poor spectator
Join Date: Aug 2006
Location: San Antonio, Tx
Posts: 2,287
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Re: Fuel Guage help
Quote:
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2006 Jeep Unlimited IMPACT ORANGE 1993 Chevy 2500 4x4 ExCab LWB 454/NV4500 Tow rig ![]() 1977 Ford F100 2x4 LWB 1st truck I owned, still have it!!! ![]() 1979 Ford F150 4x4 SWB Built Ford Tough!!! ![]() 1971 Chevy Blazer 350 / SM465 / NP205 UNDER CONSTRUCTION Soon to have a LQ4 6.0!!! |
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#4 |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
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Re: Fuel Guage help
I hate YOU AND YOUR AVATAR!
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72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#5 |
I'm a poor spectator
Join Date: Aug 2006
Location: San Antonio, Tx
Posts: 2,287
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Re: Fuel Guage help
I actually laughed out loud when I read that.
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__________________
2006 Jeep Unlimited IMPACT ORANGE 1993 Chevy 2500 4x4 ExCab LWB 454/NV4500 Tow rig ![]() 1977 Ford F100 2x4 LWB 1st truck I owned, still have it!!! ![]() 1979 Ford F150 4x4 SWB Built Ford Tough!!! ![]() 1971 Chevy Blazer 350 / SM465 / NP205 UNDER CONSTRUCTION Soon to have a LQ4 6.0!!! |
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#6 |
Registered User
Join Date: Dec 2006
Location: Wesley Chapel, Florida
Posts: 1,113
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Re: Fuel Guage help
Thanks, I found the break in the tan wire that was causing the disconnect in the circut and spliced it back together. Now the guage reads empty, so I think it is grounded out somewhere. I traced the tan wire along the frame to the tank, but did not find any grounds. However I cannot reach the fuel sending unit to see if it is gournded there too close to the bed. I think I may have disconnected the fuel sending unit from pulling on the tan wire because the guage went back to over full. Any ideas on how to get to the sending unit without dropping the tank? If not how hard is it to drop the tank?
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2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer |
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#7 | |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
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Re: Fuel Guage help
Quote:
So keeping this in mind, if the tan wire is grounded out to the frame, this would complete the circuit (before it had a chance to get to the sender) and send the fuel gauge to full. If the wire is broken fully in two that would cause an open circuit and send the gauge to empty. If the gauge is stuck at empty you should be looking for a broken wire, not a grounded out wire. That is why I suggested for you to PURPOSELY ground the tan wire and see if the gauge goes straight to full. Hope this makes sense.
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72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#8 | |
Registered User
Join Date: Dec 2006
Location: Wesley Chapel, Florida
Posts: 1,113
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Re: Fuel Guage help
Quote:
I want to make sure I have the wiring figured out before I start replacing the sending unit or gauge.
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2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer |
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#9 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Re: Fuel Guage help
Maybe it is working correctly. Maybe your float is bad. Just ground the wire first before dropping the tank. And no you can't remove the sender without dropping the tank. It's a pain, but it may need to be done.
Shawn
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#10 |
sharp as a marble
![]() Join Date: Jan 2007
Location: atlantic beach,florida
Posts: 1,082
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Re: Fuel Guage help
IF you could get to the connector at the tank, and disconnect it, you should have a TINY BIt of current. The way to check this is to use a test light. ground the light, and touch the ice pick end to the connector, or where ever the break in the wire is. If you look carefully you will see a VERY DIM blinking light. That will tell you the everything IN FRONT of you is ok. a sunk float can wear you out.
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#11 |
Registered User
Join Date: Dec 2006
Location: Wesley Chapel, Florida
Posts: 1,113
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Re: Fuel Guage help
I dropped the tank and it was completely full so it must be a float problem, but I put my meter on it anyway and had about 8 ohms. I don't know if this is normal or not. It should have a high resistance when the float is full but I don't know if 8 ohms is high enough or not. It should have low resistance when empty or if the float is sunk.
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2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer |
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#12 |
sharp as a marble
![]() Join Date: Jan 2007
Location: atlantic beach,florida
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Re: Fuel Guage help
I am going to go check. 0-90 empty to full I think?? be back soon
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#13 |
sharp as a marble
![]() Join Date: Jan 2007
Location: atlantic beach,florida
Posts: 1,082
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Re: Fuel Guage help
Cannot find what I want quickly. I am ALSMOST sure the a GM sender is 0 OHMS at empty and 90 OHMS at full. I will keep looking, but ------. I would guess the float is sunk, you will know when you remove the sender, and shake the float.
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#14 |
Registered User
Join Date: Dec 2006
Location: Wesley Chapel, Florida
Posts: 1,113
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Re: Fuel Guage help
Even before I dropped the tank, I suspected a bad float. After checking the readings that confirms it for me. Thanks for the info.
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2004 Chevy Silverado 1500LS SWB 5.3L 2004 Corvette Z16 #770 Wish I had not sold 72 blazer |
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#15 |
Registered User
![]() Join Date: Oct 2008
Location: BROOKELAND,TX
Posts: 228
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Re: Fuel Guage help
GLAD TO FIND THIS THREAD SO OK WHEN I HAD A BROKE WIRE THE GUAGE WAS WAY TO THE RIGHT OF FULL WHEN REPLACED SHOWED 1/8 OF TANK FILLED UP THE TANK NO CHANGE THEN AFTEr A WHILE OF DRIVING AROUND STARTED JUMPING AROUND AND BACK TO 1/8 [ I THINK WHEN I CHECKED CLOSE TO THE TANK SHOWED 6 OHMS BEFORE FILLING ANY IDEAS
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