Restless Fuel Gauge Needle |
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Restless Fuel Gauge Needle |
Pezz |
Apr 29 2022, 11:29 AM
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#1
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Member Group: Members Posts: 63 Joined: 4-November 19 From: Paisley Oregon Member No.: 23,621 Region Association: Pacific Northwest |
The Fuel Gauge Needle in my '75 1.8 is jumping around when I rev the engine and turn on the wipers and lights, but is stable when I turn on the heater fan, radio, and emergency flashers, and push on the brake.
In 2018, the tank was removed and cleaned, the sender, screen, gasket and fuel lines were all replaced. The last year or 2, this problem began, and has become worse now. I keep the fuel nearly full with non-eth, and this past year the gauge is reading 1/4 +/- and then falls to empty. Sometimes it begins at near full and then drops after minute or two. Routinely I turn the ignition on to heat the coil before starting, and the gauge will drop erratically. I presume to begin by testing the wire connections before pulling the relatively new sender unit. Any other suggestions? Thanks World. See a brief video here: https://youtu.be/NDds6T5DvEo |
Superhawk996 |
Apr 29 2022, 11:41 AM
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#2
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914 Guru Group: Members Posts: 5,827 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
I presume to begin by testing the wire connections before pulling the relatively new sender unit. (IMG:style_emoticons/default/agree.gif) |
Rand |
Apr 29 2022, 12:19 PM
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#3
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
Chasing dirty connections is so much fun. (That's what it is.)
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ndfrigi |
Apr 29 2022, 12:31 PM
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#4
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Advanced Member Group: Members Posts: 2,928 Joined: 21-August 11 From: Orange County Member No.: 13,474 Region Association: Southern California |
or just the grounds. You can try using a direct wire for a ground from your battery negative or good body ground to your gauge ground. Check if it will fix it.
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r_towle |
Apr 29 2022, 03:47 PM
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#5
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
That sounds like a ground issue.
Check and clean all the main ones, especially the one in the drivers footwell, inner fender, and the one in the engine bay under the relay board. Every 40 years these things need to be cleaned up. |
Pezz |
Apr 30 2022, 08:28 AM
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#6
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Member Group: Members Posts: 63 Joined: 4-November 19 From: Paisley Oregon Member No.: 23,621 Region Association: Pacific Northwest |
OK, seems you all point to check the ground connections to begin.
I didn't expect there are multiple grounds (i.e., the one in the drivers footwell). Damn,.. yes, I hate chasing electrical problems Thanks you guys... I'll report on my findings. (IMG:style_emoticons/default/blowup.gif) |
Pezz |
Apr 30 2022, 08:31 AM
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#7
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Member Group: Members Posts: 63 Joined: 4-November 19 From: Paisley Oregon Member No.: 23,621 Region Association: Pacific Northwest |
or just the grounds. You can try using a direct wire for a ground from your battery negative or good body ground to your gauge ground. Check if it will fix it. Good idea.... (IMG:style_emoticons/default/aktion035.gif) |
Superhawk996 |
Apr 30 2022, 08:45 AM
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#8
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914 Guru Group: Members Posts: 5,827 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
Better idea would be use a DMM, and a schematic and avoid guess work.
I can’t seem to understand why those two thing are overlooked as the first rational step. |
rhodyguy |
Apr 30 2022, 08:58 AM
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#9
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
Faulty fuel level sender? My car goes from 1/4 tank to empty and dead on the side of the road in an instant. I fill it up, drive 250 miles (max), and find a gas pump.
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jim_hoyland |
Apr 30 2022, 02:23 PM
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#10
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Get that VIN ? Group: Members Posts: 9,301 Joined: 1-May 03 From: Sunset Beach, CA Member No.: 643 Region Association: Southern California |
I found the the connector on the gas tank didn’t always make solid contact; while sitting in the driver seat with ignition on, have your helper grasp that connector and see whether the needle moves,
Easy test. |
Pezz |
May 1 2022, 07:54 AM
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#11
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Member Group: Members Posts: 63 Joined: 4-November 19 From: Paisley Oregon Member No.: 23,621 Region Association: Pacific Northwest |
Reading schematics are like looking at a birds nest. They don't help much showing a wire from an instrument that ends with a number instead of a description of where the wire goes. They frustrate me. I can wire a house and troubleshoot my '59 Ford 100, but my 914 is a serious challenge for me.
I use a DMM in most cases, but also I'm old school, preferring to use a long speaker wire with alligator clips on the ends, and simply bypass the circuit. I found photos of where to find the grounds. Intend to fill the tank first so I know what it should read, and almost sure it is near full right now. Thanks everyone... (IMG:style_emoticons/default/beerchug.gif) |
rhodyguy |
May 2 2022, 08:24 AM
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#12
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
I would not fill up the tank with fuel. Unless you have 3 or 4 5gallon gas cans in case you have to drain it.
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Dave_Darling |
May 3 2022, 12:12 AM
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#13
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
...They don't help much showing a wire from an instrument that ends with a number instead of a description of where the wire goes. ... That means the wire is continued on the other page. Look for that same number on the other page of the diagram; double-check that the wire color is the same. --DD |
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