Fuel gauge problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**LEEVON** · 09-29-2016, 11:09 PM

I have a new, factory style gauge set with the updated oil pressure and temp. I also have a new fuel sending unit, in a brand new tank, with brand new wiring. Both the gauge and sending unit are supposed to be as original, 30ohm. With a full tank the needle barely reads empty, but it does move from the rest position with key on. The float is not obstructed. I have tried two sending units. Is it possible the gauge is not actually 30ohm as advertised? I called Classic Parts again to be sure. Where does my troubleshooting start?

**mr48chev** · 09-30-2016, 01:37 PM

It's pretty easy to test the sending unit with an ohm meter but I've never tested the guage it's self and don't remember seeing a process for checking one.

The only thing I have done in that respect is to connect the sender to the lead from the gauge and ground and run the arm though it's arc to see if the gauge reads so that it matches the position of the sender. I've done that with aftermarket gauges and senders.

**joedoh** · 09-30-2016, 02:21 PM

I wrote up on testing a fuel sender and gauge last time this came up, here is the link

67-72chevytrucks.com/vboard/showthread.php?t=714135

**LEEVON** · 09-30-2016, 10:09 PM

Thanks fellas! Joedoh that's exactly the dumbed down diagnostic procedure I needed...will be back with results. Leevon

09-29-2016, 11:09 PM	#1
LEEVON Moderator Join Date: Jul 2006 Location: Ozark, MO Posts: 4,888	Fuel gauge problems I have a new, factory style gauge set with the updated oil pressure and temp. I also have a new fuel sending unit, in a brand new tank, with brand new wiring. Both the gauge and sending unit are supposed to be as original, 30ohm. With a full tank the needle barely reads empty, but it does move from the rest position with key on. The float is not obstructed. I have tried two sending units. Is it possible the gauge is not actually 30ohm as advertised? I called Classic Parts again to be sure. Where does my troubleshooting start? __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids

09-30-2016, 01:37 PM	#2
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,711	Re: Fuel gauge problems It's pretty easy to test the sending unit with an ohm meter but I've never tested the guage it's self and don't remember seeing a process for checking one. The only thing I have done in that respect is to connect the sender to the lead from the gauge and ground and run the arm though it's arc to see if the gauge reads so that it matches the position of the sender. I've done that with aftermarket gauges and senders. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

09-30-2016, 02:21 PM	#3
joedoh Senior Member Join Date: May 2007 Location: Doodah Kansas Posts: 7,774	Re: Fuel gauge problems I wrote up on testing a fuel sender and gauge last time this came up, here is the link 67-72chevytrucks.com/vboard/showthread.php?t=714135 __________________ the mass of men live lives of quiet desperation if there is a problem, I can have it. new project WAYNE http://67-72chevytrucks.com/vboard/s...d.php?t=844393

09-30-2016, 10:09 PM	#4
LEEVON Moderator Join Date: Jul 2006 Location: Ozark, MO Posts: 4,888	Re: Fuel gauge problems Thanks fellas! Joedoh that's exactly the dumbed down diagnostic procedure I needed...will be back with results. Leevon __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids

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