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Thread: Fuel Gauge Issues Again....
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kansei
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Posts: 423
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posted June 10, 2008 06:42 PM |
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Fuel Gauge Issues Again....
OK, I'm willing to admit I'm not the brightest bulb in the shop, and I have to admit defeat on this and hope one of you can definitively steer me in the right direction again. My good truck is a 1974 model. The only gauge in the cluster that did not work when I bought the truck was the fuel level gauge. I recently swapped in an NOS level sender, correct and REPU specific. I installed the new sender in the exact orientation as the old one came out. The fuel gauge still did not register, even with me adding over six gallons of fuel to the small amount of fuel that was already in the tank. The 'hot' at the sender shows continuity with the 'hot' at the cluster connector at the back of the gauge cluster. The 'cold' at the sender shows continuity with body ground (bed, top of tank, and frame rail). I even got anal and made sure each screw securing the sender to the tank was grounded (and they are all new), as well as the sender body itself. I swapped in a spare cluster I have here (1974 as well), that cluster also has a dead fuel gauge (and dead tachometer). What the heck am I missing or overlooking? Is there a relay or voltage stabilizer somewhere in the wiring that my truck needs replaced or may be missing? Not having a working fuel gauge is just too annoying for me to live with. I can't find my 1974 manual (prcracer beat me out on the one on eBay this week) to see if there is a dedicated fuse for the fuel gauge somewhere that I am unaware of.
Somebody help, please!
TIA,
Neal.
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ovquick
Redlining
Posts: 253
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posted June 11, 2008 01:52 AM |
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Fuel Gauge
Hello Neal,
I looked at my 77 wiring diagram and it only shows the 1 10 amp fuse for all the gauges, not a seperate one for the fuel gauge. Hope this helps.
PS. I would just fill it up, zero the trip meter and fuel before reaching 320 miles for average driving (16X20)Never ran it out of gas using that method.
____________
Manteca Mazda Asylum
where a boy and his cat live, without adult supervision
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ovquick
Redlining
Posts: 253
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posted June 11, 2008 01:59 AM |
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Fuel Gauges
Forgot, if you would like, send me your email and I'll send you the manual pages with the trouble shooting/checking for the gauge and the sending unit.
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Manteca Mazda Asylum
where a boy and his cat live, without adult supervision
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Klaus44
Redlining
Posts: 365
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posted June 11, 2008 11:38 AM |
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If it's not the gauge itself that's stuck...
...and everything at the tank (sending unit) checks out... then it's probably an issue in the wiring/connectors between the sending unit, and the gauge, would be my guess.
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datsunrides
Revvin Up
Posts: 58
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posted June 11, 2008 07:41 PM |
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If you ground the wire that goes to the gauge at the sender, it should peg the gauge if the gauge is good. If it does, your new sender is defective. If it doesn't, there is a break in the wiring ( which you confirmed is not by a continuity check) or a bad gauge. Also, take a close look at the printed circuit and trace it back to the harness connector and make sure there is not a break/short there. Easy to overlook that one.
Mark
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kansei
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Posts: 423
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posted June 12, 2008 04:18 AM |
 Edited By: kansei on 12 Jun 2008 04:29 |
Hmmm....
Thanks for the ideas guys... I think Mark may have it there with verifying that the new sender is actually good, and on the printed board (yep, I overlooked that). I'll try grounding that sender out after work today and see what that nets me. On the one hand, I hope the gauge pegs, so I know it's good, on the other hand, I hope it doesn't, 'cause then my new, irreplaceable sender is kaput! I suppose that scenario wouldn't be the end of the road, though, as there are many places that specialize in restoring/repairing senders.
I'll let ya know.
Neal.
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kansei
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Posts: 423
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posted June 12, 2008 05:12 PM |
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Well... I'm relieved and frustrated. I grounded the circuit and the gauge pegged to Full. Good gauge, bad NOS sender. Figure that one out. Bummer. Gotta spend even more money now.
Just like all my other rotaries, this one never stops draining my bank account either.
Thanks for the tip on checking the gauge. I know that should have been an obvious first or second step.
Neal.
PS- Just curious- does anyone's fuel gauge still work?
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sparky
Redlining
Posts: 299
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posted June 12, 2008 06:11 PM |
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Ever heard of a slidewire? It's a variable resistance electronic device. I have troubleshot these before. The fuel sender works off the same principle. It has a metal wiper that rides on a metal spring to vary the electrical resistance sensed back at the guage. With a basic multimeter you shuld be able to check the sender. Sometimes bending the metal tab thats the wiper will restore function. If its not that then you might have a broken wire. I like to check wires with a meter and perform a wiggle test to varify function. Happy hunting.
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mazdarx605
Redlining
Posts: 314
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posted June 12, 2008 06:12 PM |
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quote:
PS- Just curious- does anyone's fuel gauge still work?
Mine does.
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mwpayne
Hauling
Posts: 195
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posted June 12, 2008 07:13 PM |
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Mine, too. I'm like you, though, I could NOT stand it if it didn't...
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ovquick
Redlining
Posts: 253
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posted June 12, 2008 07:33 PM |
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Fuel Gauge Issues Again
Mine works also, in all of my trucks, except one. That's really and excellent average considering the age of these things.(85.7%or 1 out of 7)
The sending unit should read the following resistances when checked, Full, 2.5, +5-2 ohms, 1/2, 43, +/- 5 ohm, E, 88, +/- 1 ohm.
The fuel gauge should read when checked with the following resistances, F, 12 ohm, 1/2, 42 ohm, E, 82.5 ohm. The gauge tolerance is +/- 2 needle widths
____________
Manteca Mazda Asylum
where a boy and his cat live, without adult supervision
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Klaus44
Redlining
Posts: 365
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posted June 13, 2008 11:22 AM |
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Mine did the last time I checked...
...and every time it quit working in the past, it was always a grounding issue due to rust/corrosion at the tank/sending unit.
The usefulness of a "de-ox-it" type professional electrical contact cleaner, even in the smallest of quantities, cannot be overstated when it comes to repair and maintenance of aging electrical components and systems...
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mwpayne
Hauling
Posts: 195
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posted June 13, 2008 02:40 PM |
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Hey Klaus, you mention that stuff a lot, can you buy it on line somewhere? I'm less than satisfied with my radio shack equivalent.
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Klaus44
Redlining
Posts: 365
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posted June 13, 2008 03:00 PM |
Edited By: Klaus44 on 13 Jun 2008 15:01
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Unknown...
quote:
Hey Klaus, you mention that stuff a lot, can you buy it on line somewhere? I'm less than satisfied with my radio shack equivalent.
I only know about it from my buddy Mike, who's an electronics tech... I do know it can be obtained in some form from professional electronics repair specialty suppliers... and that the version(s) those places carry will most likely be far more expensive, and possibly far more effective, than the dumbed-down 'consumer' versions currently on the market.
Look for a very small aerosol can, brand name 'Caig' or 'Cramoline' "De-ox-it", etc. It may have changed names over the years. A teensy dab will do ya! Heavy spraying is almost always much more than actually nessecary. It can be like a miracle cure in a can...
You might find it online(?) I haven't searched.
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datsunrides
Revvin Up
Posts: 58
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posted June 14, 2008 01:49 PM |
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Well, at least you found the problem. I would try to bend the arm on the sender to make sure it has good contact. Reconnect it to the wire outside of the tank before you drop it back in and raise and lower the arm to check the functionality of the sender. Be aware these do not instantly respond, it takes a little bit for the gauge to move. Would drive you crazy driving down the road if there was immediate movement to level changes. (think sloshing)
Mark
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