Another fuel gauge problem!

BIGBLAINE · 04-08-2009, 03:58 PM

I am new here! Hello all. I have read all the posts and really feel hesatent to post another gauge problem! But i have a 1990 silverado 2500, 5.7L engine. The fuel gauge read 1/4 when i got the truck used. I put in a new sending unit and still tops off at 1/4 tank on gauge. Now when the fuel is at 1/4 tank the gas gauge will move as i turn corners, but above that fuel level its pretty much stable! Im not sure if theres somthing stopping the float or its somthing behind the dash. But i did see the gauge go to full when i unplugged the sender. So if that helps. Is there somthing in the tank that could seriously ubstruct the float?

Maybe theres a regulator for dash gauge? Im not sure. But i thank you for your time.

crabtruck · 04-09-2009, 03:09 AM

Welcome to the forum BIGBLAINE.
New sender makes this more interesting.

Showing full when unplugged is good news
in that it shows you do not have a ground short
in the wire going to gauge.
Try unplugging the sender again at tank, and
shorting that wire that goes to gauge to ground.
That should give you a dash read of empty.

Last test of the gauge end of things would be
to unplug the sender and ground the gauge wire
from dash to ground through a 90 (or 100) ohm resistor.
If you don't have one, places like radio shack sell
them for less than $1. Use a 1/2W not 1/4W if
possible because it's easier to handle and less
likely to break. This acts like the sender would
if there was a full tank of gas and gauge should
read full.

If you do not get grounding=empty and also
ground-thru-resistor=full, then the gauge may be bad.
Believe that truck uses a 2 coil gauge which means
it would not be effected by system or battery voltage.
Should read right regardless.

If the problem persists, it is sender/tank specific.
Do you have the right sender for this tank,
not just this truck ? Some tanks are shaped differently
at the bottom causing the sender to sit higher.
If you swapped the identical part to old one,
did it ever read right on old one? Does the gauge
read lower than 1/4 tank ever from fuel level,
not just shaking truck or making turns ?

Hope some of this gives you something to go on.
Good luck.

silverhairdeere · 04-09-2009, 12:34 PM

Quote:

Originally Posted by crabtruck

Welcome to the forum BIGBLAINE.
New sender makes this more interesting.

Showing full when unplugged is good news
in that it shows you do not have a ground short
in the wire going to gauge.
Try unplugging the sender again at tank, and
shorting that wire that goes to gauge to ground.
That should give you a dash read of empty.

Last test of the gauge end of things would be
to unplug the sender and ground the gauge wire
from dash to ground through a 90 (or 100) ohm resistor.
If you don't have one, places like radio shack sell
them for less than $1. Use a 1/2W not 1/4W if
possible because it's easier to handle and less
likely to break. This acts like the sender would
if there was a full tank of gas and gauge should
read full.

If you do not get grounding=empty and also
ground-thru-resistor=full, then the gauge may be bad.
Believe that truck uses a 2 coil gauge which means
it would not be effected by system or battery voltage.
Should read right regardless.

If the problem persists, it is sender/tank specific.
Do you have the right sender for this tank,
not just this truck ? Some tanks are shaped differently
at the bottom causing the sender to sit higher.
If you swapped the identical part to old one,
did it ever read right on old one? Does the gauge
read lower than 1/4 tank ever from fuel level,
not just shaking truck or making turns ?

Hope some of this gives you something to go on.
Good luck.

man this man is good , is he the chuck of truck form , hope he doesn't flash on me .

shd

crabtruck · 04-10-2009, 12:08 AM

Quote:

Originally Posted by silverhairdeere

man this man is good , is he the chuck of truck form ,
hope he doesn't flash on me . shd

I have absolutely NO idea what that means !

So...
A) Thanks dude.
or
B) I'll get ya for that.

Whichever is more appropriate.

BIGBLAINE · 04-10-2009, 09:57 PM

Well the stock sender did the same thing, The new sender is exact for the 34 gallon tank i have. I am at a loss. The resistor trick does work like you said, but still gauge goes up to 1/4 than stops until gas is down to 1/4 or less! I am leaning toward tank issue.

crabtruck · 04-11-2009, 12:19 AM

Stop leaning, you're making progress by process of elimination.
Pull the sender from tank and operate it by hand,
grounding required of course. Avoid sparking

BIGBLAINE · 04-12-2009, 12:25 AM

Is there a baffle that can interfere? In the gas tank.

crabtruck · 04-12-2009, 05:18 AM

Not that I know of

silverhairdeere · 04-12-2009, 05:23 AM

Quote:

Originally Posted by crabtruck

I have absolutely NO idea what that means !

So...
A) Thanks dude.
or
B) I'll get ya for that.

Whichever is more appropriate.

sorry i thought you were a tv & movie nut like me (and you get a A+ in my book)

http://en.wikipedia.org/wiki/Chuck_(TV_series)

shd

crabtruck · 04-12-2009, 06:05 AM

OK, so I guess I go with "A)"

Never managed to catch that show, saw the ads for it.

It's funny, my tv is ten times the size of my first tv,
and I watch it about ten times less.
Usually when I'm watching tv I also am reading a book.
Keeping up with most stuff for either is not that big a job.
Movies and comedy both are getting kinda pathetic
with lots of rehashes of old movies and jokes, and most
not as good as the original. Watched a 1958 movie
the other night and it was better done than most new stuff.
TV mostly makes me cranky cause I'm intellectually picky
when it comes to the work of folks claiming skill.
My wife tells me she likes about 8 different tv shows,
but I say they're all the same show, just the names change.
Basically, I'd prefer to watch something I haven't seen.

Thanks for the compliment even if I was slow on the uptake.
I get that way in my little bubble sometimes.

04-08-2009, 03:58 PM	#1
BIGBLAINE Junior Member Join Date: Apr 2009 Posts: 9	Another fuel gauge problem! I am new here! Hello all. I have read all the posts and really feel hesatent to post another gauge problem! But i have a 1990 silverado 2500, 5.7L engine. The fuel gauge read 1/4 when i got the truck used. I put in a new sending unit and still tops off at 1/4 tank on gauge. Now when the fuel is at 1/4 tank the gas gauge will move as i turn corners, but above that fuel level its pretty much stable! Im not sure if theres somthing stopping the float or its somthing behind the dash. But i did see the gauge go to full when i unplugged the sender. So if that helps. Is there somthing in the tank that could seriously ubstruct the float? Maybe theres a regulator for dash gauge? Im not sure. But i thank you for your time.

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04-09-2009, 03:09 AM	#2
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,110	Welcome to the forum BIGBLAINE. New sender makes this more interesting. Showing full when unplugged is good news in that it shows you do not have a ground short in the wire going to gauge. Try unplugging the sender again at tank, and shorting that wire that goes to gauge to ground. That should give you a dash read of empty. Last test of the gauge end of things would be to unplug the sender and ground the gauge wire from dash to ground through a 90 (or 100) ohm resistor. If you don't have one, places like radio shack sell them for less than $1. Use a 1/2W not 1/4W if possible because it's easier to handle and less likely to break. This acts like the sender would if there was a full tank of gas and gauge should read full. If you do not get grounding=empty and also ground-thru-resistor=full, then the gauge may be bad. Believe that truck uses a 2 coil gauge which means it would not be effected by system or battery voltage. Should read right regardless. If the problem persists, it is sender/tank specific. Do you have the right sender for this tank, not just this truck ? Some tanks are shaped differently at the bottom causing the sender to sit higher. If you swapped the identical part to old one, did it ever read right on old one? Does the gauge read lower than 1/4 tank ever from fuel level, not just shaking truck or making turns ? Hope some of this gives you something to go on. Good luck.

04-10-2009, 09:57 PM	#5
BIGBLAINE Junior Member Join Date: Apr 2009 Posts: 9	Well the stock sender did the same thing, The new sender is exact for the 34 gallon tank i have. I am at a loss. The resistor trick does work like you said, but still gauge goes up to 1/4 than stops until gas is down to 1/4 or less! I am leaning toward tank issue.

04-11-2009, 12:19 AM	#6
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,110	Stop leaning, you're making progress by process of elimination. Pull the sender from tank and operate it by hand, grounding required of course. Avoid sparking

04-12-2009, 12:25 AM	#7
BIGBLAINE Junior Member Join Date: Apr 2009 Posts: 9	Is there a baffle that can interfere? In the gas tank.

04-12-2009, 05:18 AM	#8
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,110	Not that I know of

04-12-2009, 06:05 AM	#10
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,110	OK, so I guess I go with "A)" Never managed to catch that show, saw the ads for it. It's funny, my tv is ten times the size of my first tv, and I watch it about ten times less. Usually when I'm watching tv I also am reading a book. Keeping up with most stuff for either is not that big a job. Movies and comedy both are getting kinda pathetic with lots of rehashes of old movies and jokes, and most not as good as the original. Watched a 1958 movie the other night and it was better done than most new stuff. TV mostly makes me cranky cause I'm intellectually picky when it comes to the work of folks claiming skill. My wife tells me she likes about 8 different tv shows, but I say they're all the same show, just the names change. Basically, I'd prefer to watch something I haven't seen. Thanks for the compliment even if I was slow on the uptake. I get that way in my little bubble sometimes.