Your donations help keep this valuable resource free and growing. Thank you.
|
70 Javelin - Low Fuel Warning / Fuel Gauge Issue |
Post Reply |
Author | |
worm611
AMC Apprentice Joined: Oct/12/2022 Location: Denver, PA Status: Offline Points: 75 |
Post Options
Thanks(0)
Posted: May/27/2023 at 10:55am |
Hey all,
Been fighting with my fuel gauge, Low Fuel Warning Light is basically always on. Read some other forum posts, but didn't exactly answer what I think I need. Current state: - Low Fuel Warning Light starts blinking about 2 seconds after Ignition is ON - Fuel Gauge starts to come off of E, then drops down to below E shortly after ignition is turned ON, about the time the Low Fuel Warning Light starts to blink. My original sending unit was bad, the float was full of fuel when I pulled it out. Replaced the sending unit, and while I was at it I put a new fuel tank in it as well. At the Yellow Wiring going to my fuel gauge and ground I get 22-24 Ohms, which should be about correct since put in 5ish gallons of fuel. I don't fully understand how this Low Fuel Warning Relay works, is there a sensing circuit in the relay that measures the Ohms, and if it sees +/- 1/4 tank, which is about where I'm sitting now, opens the sending unit circuit? It is a bit confusing to me. I pulled the relay off the harness and the Fuel Gauge never moved, so I guess it needs to stay in the circuit, or is there a way to bypass it? I was under the impression the Yellow Wire from the sending unit ran straight to the gauge but I guess that is not exactly true. So basically, how does the relay internally function, and why is it so quick to react when I turn the ignition ON? Its like it doesn't give it enough time for the gauge to read the proper level before going into "Warning" I'm leaning towards it being a relay issue, and not a gauge issue, but I have no clue how long that old sending unit has been bad for, so maybe something got damaged. Thank you, Jeremy
|
|
304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9081 |
Post Options
Thanks(1)
|
The low fuel warning system bypasses the gauge from the printed circuit. The IVR volage input of the gauge has a plastic washer to insulate from conductivity, under the speed nut. The low fuel warning module power draws power from a pin near the IVR. There is a plug from the IVR to power the gauge. To remove low fuel warning system, unplug the wire from the printed circuit and remove the plug and plastic washer from gauge connection. The gauge should properly function without it. The modules wear out eventually.
|
|
71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
|
worm611
AMC Apprentice Joined: Oct/12/2022 Location: Denver, PA Status: Offline Points: 75 |
Post Options
Thanks(0)
|
And that IVR is the rectangular one with 3 prongs next to the Temp Gauge and Fuel Gauge, I assume? Which I did test with my fluke meter and seems to be working ok.... I can set Min/Max and log it. I even pulled it out, cleaned up the tabs which looked good, circuit board looks good. I can't say I noticed any plastic insert, or anything out of the ordinary, but can't say I was looking for this little insert either.
I will check tomorrow, greatly appreciate the info!
|
|
rodhhrod
AMC Addicted Joined: Jul/11/2010 Location: Oregon Status: Offline Points: 1040 |
Post Options
Thanks(1)
|
PM sent
|
|
worm611
AMC Apprentice Joined: Oct/12/2022 Location: Denver, PA Status: Offline Points: 75 |
Post Options
Thanks(0)
|
So the plastic washer, is part of the bulb holder for the Low Fuel Warning light, I guess that is what had me confused.
So basically what I did, was pull the green wire off the pin as you suggested, and then also removed the bulb holder (washer), now I am reading half a tank, which is probably a little high, but at least I am reading something! So, what is the actual issue? The low fuel warning relay I assume? Thanks again! Jeremy
|
|
Post Reply | |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |