Fuel Gauge is acting wonky

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I changed the alternator and battery in my 2002 100 series and my fuel gauge has been acting up. I filled up the tank then drove over 250 miles and my tank reads that it is almost half full with the fuel light coming on. I then went to the gas station and I put in another full tank of gas. Not sure if it is the gauge or the fuel sensor thing. Has anyone had this issue and if there a remedy for it?

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I took apart a sender, it's easy to see how it could get stuck somewhere in the middle of the trace. You'd think one good bounce and it would fall to level. BUT the copper will be really dirty in the middle of the board.
 
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My fuel gauge is stuck in the exact same position. The light does not come on though. I need to pull the sending unit to inspect it.
 
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I took apart a sender, it's easy to see how it could get stuck somewhere in the middle of the trace. You'd think one good bounce and it would fall to level. BUT the copper will be really dirty in the middle of the board.
Did you find a video or instructions on how to do it?
 
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its a regular mechanical float, in the tank, under the second row seat. Metal cover on the pump holder with black plastic clips and a screw, cigarette packet sized. it could just as easily be the needle in the meter also.

IMG_20181020_092441.jpg
 

abuck99

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No I haven’t messed with it. Are you having the same issue?
I am noticing some weird behavior. I thought I was loosing my mind ( maybe I am) but it would show 3/4 then a short while later below 1/2, and I was thinking " I swear my gauge was higher when I glanced at it just a few minutes ago". Anyway I filled the other day- drove maybe 50 miles and it showed 1/2 full. Went and topped it off - it took 4 gallons and then showed 3/4full. In the morning it showed full. So I am having some intermittent inaccuracy. For the past few months I've only let the tank get to 1/2full before refilling. I'm wondering if its getting stuck. There really aren't many threads on the issue here, so the thought of bad float sensor was further down on the list and the possibility of a ground issue somewhere else affecting the gauge needle was on my mind until I saw JerryB's post.

its a regular mechanical float, in the tank, under the second row seat. Metal cover on the pump holder with black plastic clips and a screw, cigarette packet sized. it could just as easily be the needle in the meter also.

View attachment 1955331
Great timing Jerry- interesting to see the guts the float sensor. Is this one shown working correctly? Wonder if you can take some voltage readings at different E, 1/2, F so I can test against mine when I pull it. IDK- I may just replace it of I dig in that far I want to have a new part on hand so I dont have to go back in again.
 
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that pic was AFTER cleaning, lol. It was probably the worst looking trace I've ever seen on a oil or fuel needle. I didn't test it, I just cleaned, and only because I was checking three different fuel pumps back then. I had the tank open for a few days. It worked fine before I cleaned it. I did it just because it was sitting there.

there's probably fsm specs, maybe, in the book. Probably not a fool proof way to determine whats up, other than right then and there with ambient temp.
 

abuck99

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that pic was AFTER cleaning, lol. It was probably the worst looking trace I've ever seen on a oil or fuel needle. I didn't test it, I just cleaned, and only because I was checking three different fuel pumps back then. I had the tank open for a few days. It worked fine before I cleaned it. I did it just because it was sitting there.

there's probably fsm specs, maybe, in the book. Probably not a fool proof way to determine whats up, other than right then and there with ambient temp.
Jerry-

My fuel gauge continues to behave poorly. Low fuel light flickered on & off at start up today. I had the battery disconnected for a few hours doing the alternator so that reset my trip meter to 0 and I lost track of miles since last fill up. Went to fill it up and took 14 gallons so there was 10 gal left in the tank and nav screen showing 31 miles DTE. Based on your photos of the sensor unit- mine is probably got the same build up and causing the erratic readings. As for tank sensor vs faulty gauge I would think the sensor before the gauge in the cluster has failed. So replacing the sensor/float mechanism is in order. Question is at 195k miles- I probably should replace the fuel pump now since I will have the seats out, and pump & assemble out of the tank. I'd hate to have to go back in 10k miles to do a FP. Thoughts?
 
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idk Exactly.
the DTE comes from the meter so I just assume whatever the needle says, is also what the nav screen says.
I think the motors the PCB for all those gauges on the late combo meter look different, far as I know from the early 100s.

I also know you can set the needle to wherever you want it to be on the late 100s meter. Meaning you can roll the needles to wherever you want them while the car is running.
I set my speedometer that way to read correct at 50mph so it's really good at 25-70mph. That's a hassle though separating that part of the panel.

I'd take the fuel float out and power it up with jumpers on the tank cover base and rotate through its range and see what the needle does. The fuel wires of that plug aren't going to be hot with key on but the float level will be. That should be a really easy test.
I don't know how it would act surrounded by air though. I'd spray it off with contact cleaner and cover the hole back up with towels before I did that. I'm sure you know what I'm getting at.

I'm pretty sure the 2005 has one plug each for pump and sender submerged, with a 5 wire single plug on top the white cover.
SO should be easy to remove and the sender and check with the white cover setting back down on the tank opening with jumpers on top.

Before I messed with taking the meter apart and dealing with possibly replacing the motors on the board I would definitely mess with that needle in conjunction with manipulating the tank level sender.

IMG_20190429_140735.jpg
 

abuck99

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idk Exactly.
the DTE comes from the meter so I just assume whatever the needle says, is also what the nav screen says.
I think the motors the PCB for all those gauges on the late combo meter look different, far as I know from the early 100s.

I also know you can set the needle to wherever you want it to be on the late 100s meter. Meaning you can roll the needles to wherever you want them while the car is running.
I set my speedometer that way to read correct at 50mph so it's really good at 25-70mph. That's a hassle though separating that part of the panel.

I'd take the fuel float out and power it up with jumpers on the tank cover base and rotate through its range and see what the needle does. The fuel wires of that plug aren't going to be hot with key on but the float level will be. That should be a really easy test.
I don't know how it would act surrounded by air though. I'd spray it off with contact cleaner and cover the hole back up with towels before I did that. I'm sure you know what I'm getting at.

I'm pretty sure the 2005 has one plug each for pump and sender submerged, with a 5 wire single plug on top the white cover.
SO should be easy to remove and the sender and check with the white cover setting back down on the tank opening with jumpers on top.

Before I messed with taking the meter apart and dealing with possibly replacing the motors on the board I would definitely mess with that needle in conjunction with manipulating the tank level sender.

View attachment 1965068
Thanks for the detailed reply.

When you say “adjust the needle”- are referring to the needle in the guage instrument panel.

Why did you have your level sensor out of the tank in the first place? Were you replacing FP or did you have some other issue.
 
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yes the needle in the guage instrument panel.

that pic was AFTER cleaning, lol. It was probably the worst looking trace I've ever seen on a oil or fuel needle. I didn't test it, I just cleaned, and only because I was checking three different fuel pumps back then. I had the tank open for a few days. It worked fine before I cleaned it. I did it just because it was sitting there.

there's probably fsm specs, maybe, in the book. Probably not a fool proof way to determine whats up, other than right then and there with ambient temp.
 
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abuck99

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yes the needle in the guage instrument panel.

that pic was AFTER cleaning, lol. It was probably the worst looking trace I've ever seen on a oil or fuel needle. I didn't test it, I just cleaned, and only because I was checking three different fuel pumps back then. I had the tank open for a few days. It worked fine before I cleaned it. I did it just because it was sitting there.

there's probably fsm specs, maybe, in the book. Probably not a fool proof way to determine whats up, other than right then and there with ambient temp.
Thanks for the input. I figure if Im going to go to the trouble of ripping the back seats out of the truck and open the tank Im going to replace sending unit and FP & filter while Im in there. If that doesnt solve it, I’ll move to the instrument cluster and start on the gauge.

Fwiw Seems as everything heats up after a 20mile drive the guage responds more accurately.
 

abuck99

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There is test procedure for the sender: says to hook up a battery- the image is 3 small battery's together- what voltage battery I haven't determined yet . (Seems to me measuring resistance would be an easier methodology)

1965752


For testing the gauge
1965763
 
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My 04 started doing the same, showing low fuel at startup and slowly coming up. Good info here to get started, thanks
 
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probably looking for 5 vdc. any size, 4.5 I guess with any three batteries.

the 6 and 7 manual don't have that pic in the instrument panel info, I think they are completely different, I see they say stopper assuming they mean a needle resting position. The 06 and 7 don't have needle stoppers.
I'm sort of at a loss, I lost my high beam indicator, the blue light. I'm not the guy that can solder on the back of that circuit board.

I just took the double sized seat out, not both, to do the fuel pump. It's really pretty fast/easy.
new denso pumps can be had for cheap/er from Find My Part

have extra yellow fuel line clips incase you fling one off or bend it all up.
 

abuck99

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probably looking for 5 vdc. any size, 4.5 I guess with any three batteries.

the 6 and 7 manual don't have that pic in the instrument panel info, I think they are completely different, I see they say stopper assuming they mean a needle resting position. The 06 and 7 don't have needle stoppers.
I'm sort of at a loss, I lost my high beam indicator, the blue light. I'm not the guy that can solder on the back of that circuit board.

I just took the double sized seat out, not both, to do the fuel pump. It's really pretty fast/easy.
new denso pumps can be had for cheap/er from Find My Part

have extra yellow fuel line clips incase you fling one off or bend it all up.
Thank you Sir- I tend to order everything I need ( and then some) ahead of pulling stuff apart, but I hadn't considered extra clips. I'll have to be extra careful. Appreciate the tip on seat removal- I was thinking about it today wondering if both the double and single needed to come out.

Current pump works fine but I went ahead and ordered a new Denso replacement pump kit ( pump, strainer, hose, orings, tension clamps) Monday and placed the order for the sending unit and gasket today. Since I am at 195k & 14yrs, everything gets replaced when I pull the cover off the tank.

I am hopeful that solves it and its nothing to do with the actual gauge. I looked online for a replacement and its NLA, even the instrument cluster is NLA. Crazy that you can still get a 80 series fuel gauge, but not the 100.
 
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