Random and erratic fuel level????

[FLYNAVY53]

2002 4Runner....just crossed 250K miles. Started the truck a couple weeks ago and noticed the fuel level was below E and the warning light was on. I knew this wasn't accurate because I had filled up the day prior. As I was driving, I watched the fuel level slowly climb above E, and the light go out, but it never showed above 1/4 tank. After work, when I started the truck up again, the needle was indicating accurately at Full.

This has been an ongoing cycle of sometimes the gauge indicates correctly, and sometimes it shows below empty, then slowly creeps up over time.

My initial thought was of course fuel sending unit but in my experience with bad fuel sending units, they just fail and the needle doesnt move. Ive never seen one that bounces between indicating correctly and varying degrees of inaccurate.

Any thoughts or helpful troubleshooting steps would be greatly appreciated. I dont want to go through the effort of changing the sending unit if that isnt the cause of the issue.

Thanks!

 

[brillo_76]

Search the forum for this issue. The 01 and 02 are known for this issue.. Those same threads have ways for you to fix the issue. How to search is stickied at the top of this forum. lots of threads on here on that topic

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[FLYNAVY53]

got it, much appreciated!!!

 

[gamefreakgc]

There is a TSB (Toyota Service Bulletin) about this issue for certain years but not sure if 2002 was one of them. It involved an issue with the gauge cluster, not the sending unit itself. That being said these gas gauges are known to have issues and be innacurate. While mine is more accurate than yours, it drops to beyond E with 5 gallons left in the tank. Then one time it didn't and I ran out of gas just as I was turning into a gas station and rolled up to the the pump unpowered! Removing the sending unit and cleaning the contacts made no difference for me (I was installing a new fuel pump at the time).

My best advice is to use the trip odometer and reset when you fill up the gas. Most can safely go 225 miles with some reserve fuel left with stock sized tires. Adjust accordingly.

 

[brillo_76]

There is a TSB (Toyota Service Bulletin) about this issue for certain years but not sure if 2002 was one of them. It involved an issue with the gauge cluster, not the sending unit itself. That being said these gas gauges are known to have issues and be innacurate. While mine is more accurate than yours, it drops to beyond E with 5 gallons left in the tank. Then one time it didn't and I ran out of gas just as I was turning into a gas station and rolled up to the the pump unpowered! Removing the sending unit and cleaning the contacts made no difference for me (I was installing a new fuel pump at the time).

My best advice is to use the trip odometer and reset when you fill up the gas. Most can safely go 225 miles with some reserve fuel left with stock sized tires. Adjust accordingly.

I thought you fixed your gauage. Sometimes, these 01 and 02 get an iffy ground to the tank, too. It's a shame this sending units act up. The 1996 to 2000 are analog instead of digital. Thus, it seems to be a lot more dependable.

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[FLYNAVY53]

Just read through a bunch of those threads.....hard to get a consensus on the actual fix....especially for the 01-02 trucks.....is bad tank ground the general consensus for the later trucks??

 

[brillo_76]

Just read through a bunch of those threads.....hard to get a consensus on the actual fix....especially for the 01-02 trucks.....is bad tank ground the general consensus for the later trucks??

Lots of times, you are correct, though. Lots of times for whatever reason. The 01 and 02 can lose their ground.

Can also be the sending unit or the gauage too.

Just a great place to start...

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[gamefreakgc]

Just read through a bunch of those threads.....hard to get a consensus on the actual fix....especially for the 01-02 trucks.....is bad tank ground the general consensus for the later trucks??

Agree with Brillo, gotta start somewhere if you want to fix it. The gauge cluster (can be removed in 15-20 minutes) and grounds are the easiest and obviously replacing the sending unit is the hardest and most expensive.

In the meantime just be sure to keep that tank full.

 

[FLYNAVY53]

Agreed on all accounts. Going to start with the ground....thought I'd like to find a good wiring diagram and instead of just jumping a second ground in there with a self tapping screw, Id like to either find the source of the "bad ground", or de-pin the factory connector, pin a new wire, and run it directly to the negative side of the battery to avoid any issues in the future.

If that isnt it, Ill start exploring gauge cluster and sending unit issues.

 

[brillo_76]

Why not clip a jumper cable on the tank and see if it fixes it?

Lots of the threads just added another ground path to solve it. Keep in mind that these [01-02] are digital sending units. Not like the old [96-00] are just variable resister on a float.

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