Backstory: 2001 4Runner, 482,518 miles at the time of this post. I've owned the truck since new and it's left me stranded exactly one time - when the original fuel pump gave up the ghost three years ago at 400,000 miles. Because of time constraints, I initially installed a cheap-o parts store fuel pump. If you've ever dropped one of these tanks, you are fully aware of just how tedious it is....
After one year the fuel pump began buzzing, so I purchased a new one from Toyota, dropped the tank again, and installed what I should have installed the first time.
The issue: I tend to park my truck on somewhat of an incline at home - sometimes nose up, sometimes nose down. Over the last month or so, I've noticed a strange behavior with the fuel gauge. When I start the truck, it will show a much lower level than is actually in the tank and the light will be on. It will stay like that as I start driving. If I stop on level ground, turn the truck off, and turn it back on, the gauge shoots to the top and registers the correct level.

I've read numerous threads on various forums that discuss 3rd gen fuel gauge issues, but none mirrored my example. A few of the threads discussed issues with the dash cluster circuit board and a recall that affected earlier examples of the third gen.

Based on my description, is it fairly safe to assume that the float/level sender/whatever has reached the end of its usable life? If so, I'll look into purchasing a new one from Toyota and then readying myself for yet another utterly joyful & entertaining tank drop....



Andreas

 

Andreas,

I'm not sure if you caught me thread about my fuel gauge issue. I had fueled up without shutting off the truck and it took nearly an hour of driving to go from below a 1/4 tank to about 3/4 tank (even though I filled the tank all the way at the pump). The next time I started the truck it read nearly a full tank, as I did drive for a bit so I didn't expect it to read tip top full. I have since filled the tank several times, making sure to shut the truck off, and haven't had any issues with a sluggish gauge response.

If I had to guess, I'd say the value change from the sender exceeded what the stepper motor could interpret it was a constantly changing value as I refueled. Whereas when you turn the truck off, refuel, and restart it you go from one value, power down the circuit, and then power up the circuit upon restart to a new value, there is no change.

I have noticed that if I park on the slope of my driveway, versus the flat, I can trigger the fuel light if the tank is empty enough and then it takes some driving to on level road to reset it. This too would play into my theory that the sender doesn't like rapid change in values. Now whether that can be sorted with a new float and sender, or if that is on the ECU side... I don't know.

 

Dan,
Thank you for the thoughts. I tend to always shut the truck off when refueling. That said, I did overfill the tank a few times in May because I was in NC during the 'fuel shortage'.

With the miles on the truck, and the age of all of the components, I think replacing the sender assembly (~$90 from McGeorge) probably wouldn't hurt. It's just such a nightmare to drop that tank....


Andreas

 

Come to think of it, the refuel I did when I had the sluggish gauge response I DID top it off to its tip-top because I was preparing for a road trip.

I could see that playing an issue if there was a running issue, flooding the evap chamber or vapor locking the vent. That shouldn’t have impacted the gauge reading.

I think more tea leaves need to be read.

 

You are aware there's a "hatch" under the rear driver's side seat for working on the fuel pump and sending unit, without dropping the tank, yes?
Unless you've moved the tank to the other side of the truck, or something like that, there's no need to drop the tank for these repairs. Just take up the driver's side rear seat cushion, and carpeting under it, and unscrew the hatch in the floor. You can do all the testing you need to determine the trouble, and you can pull the hanger the pump and level sender are on. Pull the sender off, new one on, and put it all back in. Quick, simple, easy, and I hope, for you, painless

I have the same problem on my 87 pickup, which I would have to drop the tank out of to replace the sender in, so I'm holding off on that, for the last 20 years or so I just keep an eye on the odometer. Actually, that's the best I can do, since I only have one eye left...

I also have it on my 99 4Runner, and I'm going to have my mechanic deal with it for me. I just have too much friggen trouble with doing ANY-darn-thing to work it myself. Sorry for my language. I'm a former Marine Sergeant, though.
Oh well, I pay my man well to have the YOUNG guys, who work for him, do the work I used to be able to do. Let the kids pay the piper now

Good luck!
Pat☺

 

Pat,
Thanks for all that but I've owned the truck since new and do all of my own work. The access under the rear seat only allows you to disconnect the wiring harness for the fuel tank. Trust me.



Andreas

 

Update: I just came home from a 2,200+ mile drive since last Thursday. The fuel gauge acted perfectly normal throughout the trip. That said, I have a new Toyota float/sender unit on my bench, for when the desire for another tank drop strikes.



Andreas

 

Of course. You got a new sender unit, so now you gauge will function perfectly for the rest of the time you own the truck

Looking forward to hearing how things go for you
Pat☺

 

Just curious how much fuel is in the tank when your parked on the incline about how much incline at home?

The sending unit sits in a odd position for that time period it gets hung up the few miles of driving is enough to jar it free .

That was why it worked on your little trip without issue.

Almost 500,000 miles it can`t hurt to have a new sending unit since it is a royal pain to drop the tank Myself I would thing real hard about another new fuel pump

Just a thought.

 

It's now been about 5,000 miles since I started the thread and no reoccurrence of the strange fuel gauge behavior. Our driveway has a decent amount of slope, but I can't remember how much fuel was in the tank when the gauge acted up.

If it happens again with any regularity, I'll drop the tank and install the new sender. Since the original Toyota fuel pump lasted for 400,000 miles, I'm pretty confident that the new Toyota one I installed has a long life ahead of it.



Andreas