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Fuel gage stuck on full. HELP!

8.6K views 20 replies 13 participants last post by  DragRag  
#1 ·
I went out to change the summer wheels to the stock wheels. Started truck to back half way out of shop. Everything normal. Fuel gage on 1/8 tank. Change front wheels. Turn truck around. Change rear wheels. Flip the switch for the different tire size. Start truck and fuel gage pegs on full.

I flipped the switch again to see if it would change. Nothing.
I tapped on tank, nothing.

Anybody that has come across this please give me some insight on what is going on. Everything else is normal. I usually only drive the truck on weekend.

thanks
Josh
 
#3 ·
I tried that. /forums/images/%%GRAEMLIN_URL%%/grin.gif

I must mention. It does go down when I turn the key off, but as soon as I hit the key it goes to full.
 
#4 ·
Mine was doing the same. If I reach around to the top of my tank and wiggle my wires it stops. I was told if the sending unit goes bad it will drop to empty and if the ground wire is bad it goes to full. I have not had the time to drop my tank yet but that's what I was told to do and see if the ground wire is bad. So you can try to reach the top of the tank and wiggle the wires and see what it dose.
 
#6 ·
i had this happen to me a few months ago, fill the tank to about 3/4 tank and take it over some speed bumps at a good clip to get the fuel to slosh arround a bit.

sometimes the sender will get stuck.
 
#7 ·
I can't see where it is on mine. I was told to see all the wires to be sure that you find the bad spot in the ground you need to drop the tank. Now if someone has done this a different way where you don't need to drop the tank PLEASE LET ME KNOW!!!
 
#8 ·
Add some fuel. With just 1/8 tank you are sucking air big time. This is a good time to drop tank and upgrade your pick-up tube. Do the harpoon mod also for quick fill-up. These mods will make you smile. /forums/images/%%GRAEMLIN_URL%%/smile.gif
 
#9 ·
My tank has already been pooned and the intank mod done.

Ill check the wires tommarrow. thanks
 
#11 ·
Might not be the sender, mine is doing the same thing right now, I changed the sender, and huess what, still does it. My cluster was just changed a couple days ago to, didn't solve it either. I needed the cluster anyway, so no money wasted. I will be looking for this ground wire to see whats up with that. Does anyone know where it is grounded form the facory, my spot may be different due to having a utility body.
 
#12 ·
I don't know where the ground is. I need to drop the tank and do the tank mod so when I drop it I will look then. I know when mine dose it I can reach above the tank and shake the wires it stops and go back to normal. So right now that's what I'm doing till the weather warms up. I don't run my truck all the time like some so I can put it off.
 
#13 ·
When you drop your tank, it is a lot easier to use a couple of ratcheting straps than jacks.
 
#14 ·
The fuel sender is a varible resistor operated by the float. Low resistance = low fuel level, and high resistance = high fuel level. So if there's a break anywhere in the circuit between the cluster and the tank (or between the tank and ground connection), then the resistance will be higher than a full tank. I think the normal values are about 15 ohms empty and 160+/- ohms for a full tank. I believe the ground is all the way back near the instrument cluster, not at the tank. On a 99, the wire colors for the fuel sending unit are yellow/white for the powered side and black/orange for the ground side of the sending unit.
 
#15 ·
Thanks for the additional info, I will be looking at mine when the new engine is in.
 
#16 ·
Just a thought, I've found that it is easier for me to remove the bed than to drop the tank. 8 Bolts, 3 screws for the filler neck, and two wire connections to unplug, and it just lifts off. Two people can lift the bed with ease, just be sure to take the tailgate off first.
 
#17 ·
I can't say what happened, but i went down and filled the tank half full and checked the wires on top of tank.

While driving to the fuel station. the gage actually was going down until I got to station and put diesel in. I pegged back on full after the half tank fillup. i drove home and let truck idle in driveway checking stuff out. couldn't find anything, but as it idled the fuel gage went down and actully showed what the fuel level was. Shut truck off and started again and now it reads correctly. Wierd, but it works now.

thanks for all the replys.
 
#18 ·
Glad to hear it is now working. Since it seemed to fix itself, it is very likely dirty contact in the connection could be the culprit. I would suggest reaching up above the rear of the tank and unplugging then replugging the wire connector several times to kind of "clean" the contacts. This cured the problem on a Nissan truck a few years back.
 
#19 ·
Mine did it again this morning and I tried what David C said I could not get the plug apart but once again it went back to reading right. I think David hit it on the nose and when I get time I'm going to try to get it apart again. Thanks
 
#20 ·
i've been doing some searching for fuel gauge problems and this part of the issue sounds similar to mine but i have other "odd" issues.

truck is 99 PSD F350 DRW Auto 2WD

outside temperature has been reading off some of time. i also only drive the truck weekends and towing for race weekends. before parking for the winter and for the last race weekend, this is what happened.

1. arrived at track with a 1/4 tank of fuel.
2. left track two days later with it reading full.
3. stopped about 50 miles from the track, still reading full. shutoff truck and fueled up.
4. now reads full, no surprise, but now the speedometer does not work. use tach to monitor speed.
5. drive an hour down the road and fuel gauge seems to be tracking normally but speedo does not work. OD light is flashing like it is not in OD but it is.
6. stop at rest area for a break and shut off truck.
7. resume trip and now fuel gauge is tracking and speedo is okay. life is good.

any thoughts? truck was running great and shifting normally the whole time and no CEL.

tia,
tom
 
#21 ·
Tom,
Welcome to the forum, you will find alot of useful info here for sure. I will not have my truck back until Probably Tues. the engine install is not done. I havn't been able to verify yet if it is a grounding problem or not, or if the plugs are just dirty. Not sure on your in regards to the speedo issue, but to me it sounds like a wiring gemlin.