My 4Runner just left me stranded on the interstate...

2001, Limited, v6, 4wd, 151k miles

6 months ago, I was driving home and the 4Runner stuttered and died. I looked at the gauge and saw the fuel gauge was reading empty. I thought it was super strange since I've never run out of gas before and isn't the type of thing I'd overlook. Bought a gas canister, added 1 gal, drove it home. The next morning when I turned the key, the gauge read 1/4 full. I was a little confused but continued with life.

Occasionally while filling up at the gas station, the gas pump shuts off prematurely. I know the tank isn't full, so I wait 30 seconds and add some more. This has happened a few times.

TODAY
Drove to the gym, parked, and saw that the gauge was reading almost empty with the fuel light on. Same deal as before, I could have sworn I had 1/4 of a tank when I left. Start the car after working out and, sure enough, it reads 1/4 full.
I start to drive home on the interstate while keeping an eye on the gauge since I think there might be a problem. It starts dropping waaaayyy too fast, stutters, and dies. I give it some time to see if the gauge will pop back up. It doesn't, so I call a friend and do the gas thing. After adding 7 gallons (even though I know it has gas) the gauge still reads empty and it won't run longer than 20 seconds before dying.

Can someone please explain this to me? I'm not sure where to start troubleshooting. I know the truck has gas but it keeps dying like it has run out of gas. Do these trucks have some kind of safety system where the pump shuts off if the gauge falsely reads empty?

I'm considering ordering a new fuel pump assembly, but after doing a little research online it seems like there are other common issues with the fuel system that are typically the issue with incorrect gauges, i.e. the ground wire for the sending unit.

Any help would be greatly appreciated. My baby is just sitting on the side of the interstate right now...

There's not a safety system or shut off system if the fuel gauge doesn't read any fuel in the tank. It sounds to me like the fuel pump is your culprit.

Try replacing the gas cap first of all. There is a pre-filter in the tank that can get clogged up as sediment swishes around on inclines or whatever. There's also some sort of baffle thing in there which causes trouble but was supposed to be fixed after 2000 when they redesigned the sending unit. You can easily test the vapor pressure sensor and fuel pump from the access hole under the rear seat to rule that out.


1.INSPECT POWER SOURCE VOLTAGE OF VAPOR PRESSURE SENSOR

(a)Disconnect the vapor pressure sensor connector.

(b)Turn the ignition switch ON.

(c)Using a voltmeter, measure the voltage between connector terminals VC and E2 of the wiring harness side.Voltage: 4.5 - 5.5 V

(d)Turn the ignition switch OFF.(e)Reconnect the vapor pressure sensor connector.

2.INSPECT POWER OUTPUT OF VAPOR PRESSURE SENSOR
(a)Turn the ignition switch ON.

(b)Remove the fuel tank cap.

(c)Connect a voltmeter to terminals PTNK and E2, and mea-sure the output voltage.Voltage: 3.0 - 3.6 V

(d)Reinstall the fuel tank cap

INSPECT FUEL PUMP RESISTANCE

(a)Pull up the LH rear seat cushion.

(b)Remove the floor service hole cover with the 3 screws.

(c)Disconnect the fuel pump connector.(d)Using an ohmmeter, measure the resistance between ter-minals 4 and 5.Resistance: 0.2 - 0.3 Ω at 20∞C (68∞F)If the resistance is not specified, replace the fuel pump and/orset plate.

INSPECT FUEL PUMP OPERATION

(a)Connect the positive (+) lead from the battery to terminal4 of the connector, and the negative (-) lead to terminal5. Check that the fuel pump operations.NOTICE:These tests must be done quickly (within 10 seconds)to prevent the coil from burning out.Keep the fuel pump as far away from the battery aspossible.Always do switching at the battery side.If operation is as not specified, replace the fuel pump and/or setplate.

(b)Connect the fuel pump connector.

(c)Install the floor service hole cover with the 3 screws.

(d)Connect the LH rear seat cushion

If its the orIginal fuel pump just replace it with a denso unit also the gaskets.

Replaced the PUMP and the Fuel sending unit. There was a service bulletin years ago that said it could cause erratic fuel readings on the 99-00 I believe.

The only irritating thing is you have to drop the actual tank to do it, rather than getting at it from the rear seats, but I just made sure it was somewhat empty and use a jack to support it as I lowered it.

I did mine proactively about 10 years ago, even though it didn't display these issues. It's been solid since then.

Thanks a ton for the info and suggestions! Looks like replacing the pump is in my future. Even if I can't track down an error with a meter, it's probably a good idea.

UPDATE
I checked on the car this morning and as soon as I turned the key, the guage read about 1/3 full, so I left my Tacoma on the side of the interstate and drove the 4Runner home. So now I can troubleshoot the problem in the garage instead of on the side of the road.