LT1-LT4 Modifications 1993-97 Gen II Small Block V8

gas gauge empty at 1/4

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Old 04-13-2008, 01:14 AM
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Originally Posted by caldercay
Let's think of this another way. Ever see a Hurricane (drink) glass? Notice
the shape is wide at top, goes thin, then goes fat again. As you take a drink
from the beginning, it doesnt seem you've done much damage (unless you
gulp the damb thing). Then you get to the thin portion of the glass - when
you take another gulp, it seems the drink is dissipating faster. Then when
you get to the bottom end of the glass, things go slower.
Never heard of one, and that explanation made no sense to me

OK I googled a picture.... That helped


I've never had a sending unit go out (where it reads empty at 1/4), but all my GM vehicles have sailed to E after 1/2 and even faster after 1/4. Even my RECTANGULAR Suburban tank. I figured it was just some issue with some part GM constantly used in either the gauges or sending units.
Old 04-13-2008, 01:48 AM
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what sux is you cant buy a new one...you ahve to buy a whole pump assembely from gm


luckily its an easy fix if your careful...sending unit is a spring loaded small pieve of metal tahts slides against a wire coiled around some plastic...2 things to help fix this...1 is this coiled wire is rusted try to clean it or scratch the rust off and 2 is this spring in the meal clip needs to be restored...bend it some and clean the rust and it will read 100 times better...
i did this and got mine almost to e before it died from 1/2 tank...i replaced mine with anothing one from another car and its just like it was brand new from the factory!
Old 04-13-2008, 01:50 AM
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Originally Posted by jb442
When the stock fuel pump went out in my car @ 100K, I upgraded to a Walboro pump. As I was putting it back together, I decided to check the gauge before getting too far along... The sending units are supposed to be 0-90 ohm (empty=0,full=90) - I found the range on mine was about 12-120 ohms. I should've replaced the sending unit, but @ 12 ohms, the needle was just barely above horizontal on the gauge. When it's full, it's WAY past vertical. I think I can go about 200 miles and the gauge shows half full... Past that it moves very quickly toward E. The only way I could think of to fix it would be to splice in a device that could translate the bad signal range (12-120 in my case) to the standard 0-90 range. Any EE's out there?
Camaroholic should chime in here.
Old 04-13-2008, 02:18 AM
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Originally Posted by nomoneyz
I can run mine all the way down to E, After the first quarter it just goes fast cause of the reason stated above.
same here.
Old 04-13-2008, 02:36 AM
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Originally Posted by caldercay
Really? So, If Merv "bends the float arm", is that related to electrical or is
that related to "mechanical" ? See my point? Does the fact that the tank
is not "rectangular" fit into this equation? Plus the fact that the float/sensor
conforms only to rectangular tank(s) - does that not enter into this
"unbalanced" equation? It's simply a mis-match of the odd-ball shaped
tank using a standard float/sensor.
Ok... Yes, a fuel tank is an electro-mechanical system. The whole point of the sending unit is to provide a signal for the gauge in ohms, nothing more. There seems to be two topics here, and you're focued on the accuracy of the gauge, based on the shape of the tank. I understand why it does what it does. What I was suggesting was that if he bent the arm to touch bottom when the sending unit read zero ohms, his 'E' would be closer to accurate (His 'F' would probably be way high though... hard to say though since the sending unit seems to be messed up anyway). I wasn't suggesting this as a solution to making the the whole system accurate from E-to-F. My initial suggestion of using a device to translate my 12-120 sending unit to 0-90 could correct the range/offset of the gauge, as well as compensate for the shape of the tank, but even if it only corrected it to 0-90 it would help me.

As for the float itself, do you know it's "standard"? Did you measure this? (and by standard, I'm guessing you mean linear in movement vs. ohms). It probably is, because that would be the easiest to mfg. I could've done that test when I had the tank out, but it's obvious that it's not mached to the shape of the tank. GM could possibly have made a sending unit to match, but who knows why they didn't... I guess "empty is empty" in their eyes no matter how you got there.
Old 04-13-2008, 09:00 AM
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My goal is to make the thing read Empty when infact it is empty, hence why I am bending it to where the Float will sit right above the Pickup Filter and the Gauge read Empty.

I don't care how Full it will read.. the Car will still move then..
Old 04-13-2008, 12:31 PM
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Originally Posted by the_merv
My goal is to make the thing read Empty when infact it is empty, hence why I am bending it to where the Float will sit right above the Pickup Filter and the Gauge read Empty.

I don't care how Full it will read.. the Car will still move then..
Indeed, empty is MUCH more important than full
Old 04-14-2008, 12:20 AM
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Originally Posted by the_merv
My goal is to make the thing read Empty when infact it is empty, hence why I am bending it to where the Float will sit right above the Pickup Filter and the Gauge read Empty.

I don't care how Full it will read.. the Car will still move then..
There's an easier way to accomplish this, been there done that. I filled the tank all the way. Then, with the ignition on, let the fuel gauge go all the way up (it would go past F), and pried the gauge needle off with a pair of butter knives VERY CAREFULLY. Just as carefully pressed it back on pointing at the hash mark next to F. This way there's enough fuel left in the tank for me to drive about 15 more miles when the gauge reaches E. Since there's about 1.5" of gas still left in the tank when the float is at the lower limits of its travel, that sounds about right.
Old 04-14-2008, 09:31 AM
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Originally Posted by Jeep_junkie
There's an easier way to accomplish this, been there done that..
I made another thread on what I did.. but I have the Trap Door and it took about 40 min to take it apart and put it back together..

Personally I don't want to mess up the Guages with your way.. not saying yours did, but the Gauges can be bitchy..
Old 04-14-2008, 11:22 AM
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[QUOTE=caldercay;9140101]When I've filled up the tank, the gauge goes way past F (straight up). The
gauge "accelerates" down over mileage driven; by the time it gets to 1/4
tank, it's showing "normal". Mine does go to E.

Same here mine goes to E But when u fill it up the needle goes straight up way past the F
Old 04-14-2008, 11:26 AM
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I think all GMs go past F. Again, I recall all mine doing that as well. Not WAY past F, but it was definitely past F.
Old 04-14-2008, 03:08 PM
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Yea.. with the way it's shaped it takes a while to get to about 2/3 Tank.. under that it drops like a rock to E..

Well mine does anyways..
Old 04-14-2008, 03:32 PM
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This is a sad thread from so many people that know so much. These sending units go bad just like any other GM sending unit. When they do the Ohm load ends up way off and THAT is why the gauge doesn't work properly. Next time anyone has a problem like this check the Ohms from the sending unit and I'd bet my last dollar that it's not right. An odd shaped tank will do nothing other than make the gauge take longer to come off the full mark but still operate fine once it starts moving. jb442, you're on the right track but unfortunately you never want to "translate" a bad signal. This is your sign that the sending unit is bad and nothing other than replacing it will fix the problem. Also the contact area may just have some dirty buildup on the lower part where it picks up signal for lower fuel levels. Please guys, learn how to use a multimeter and test for this instead of making posts asking opinions from mostly kids that know nothing other than what they read on the internet.
Old 04-14-2008, 03:38 PM
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But everything in teh intarwebs IS true!! Slowmaro's a heretic!
Old 04-14-2008, 03:38 PM
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I know, it's blasphemy. Sorry guys. lol
Old 04-14-2008, 04:19 PM
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Originally Posted by infinitebird
Camaroholic should chime in here.
OK, I'll chime in.

My gas gauge is f*cked up too. Another post-Walbro screwup. I musta tweaked the float arm is all I figure.



My 93 Suburban (bone stock) is just as bad. Way past F when full, 2/3 on gauge = 1/2 tank, 1/4 tank is really 1/8 tank. Empty tank = $140 fillup. (40 gallons)
Old 04-14-2008, 05:45 PM
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Originally Posted by Slowmaro95Z28
This is a sad thread from so many people that know so much....
....Please guys, learn how to use a multimeter and test for this instead of making posts asking opinions from mostly kids that know nothing other than what they read on the internet.
I'm sorry that we are not meeting "your" Standard here..

One thing to think about is what is the reason for these Forums..to share the wealth of knowledge that is out there. Granted some people will post what they read, and others will post through experience.

Myself, I make alot of posts through experiences that I have done. Like I said, I was goin to look into my problem why my Fuel Gauge was hanging up, and I did find it. It was different from what these guys are experiencing, but still it is no reason to make a judgement/generalization that we are all mostly "kids" that know nothing other than they read. I think my Sig and a few other people Sig's here can tell you that otherwise..

Some people don't have the time or the knowledge to get out there and do the work themselves. Some people here probably don't know what a Multimeter is yet how to use it. Me personally I wouldn't sit there and call them out about it..tell them to not say anything, which is what you did in a way.

Everyone is entitled to their opinion/idea. If they think they are right and bring it out, and it's not the right way, then guess what..they just learned something when those of us that have done what they are talking about correct them and explain the proper way.

Just my .02.. we're all out here to learn something..
Old 04-14-2008, 09:37 PM
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Your situation was different and I saw that from the start. I'm sorry you took it that way. Most other people don't realize how simple it is to diagnose a problem like this. I've been doing this for a long time and offer nothing other than experience. I just don't want to see people thinking your fix will solve their problem when theirs may be different. I'm here to help just as much as the next guy. Congrats on the fix and I hope at the very lest someone might have learned something here.
Old 04-14-2008, 10:14 PM
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I hear ya..

I'm just supporting those guys that want to try and fix theirs and don't have an idea how to do so..
Some people like that give up on it..like you said it's not that hard to do, so I believe that they should atleast try.

It's all good.. hopefully they find out what's wrong with theirs.

I have a '99 GMC Seirra that has the famous Sending Unit Level Signal Malfunction. I don't feel like the $400 for the whole new one and to pull the Bed off of it is worth fixing it, it shows the Level when it decides too..usually atleast once when I drive it.
Old 04-14-2008, 10:51 PM
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Hey Merv... Thats funny you mentioned that, My 2000 Chevy Silverado 4x4 does the exact same thing, and I've replaced quite a few sending units from other trucks at my shop as well. It seems like ALL of the trucks, suburbans, tahoes, and etc. from 99+ have this problem. Even the Impalas and cadillacs from around the same years. It's amazing GM wouldn't recall this and fix them. But I guess it's a good thing for me, being that I am a technician.


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