Fuel gauge issue

Hello,

My fuel gauge just started reading like I am on empty (07 SR5) but l just gassed up with a full tank and my digital reader is showing around 275 miles so long have a way to show about how many miles l have left to go. Should l worry about this or just drive? I just don’t want to worry if there could potentially be any underlying dangerous issues. Thanks in advance!

 

On the 3rd gen (and most cars), that would be a bad sending unit in the tank. Nothing dangerous. When mine went out, I filled her up, zeroed the trip meter and made sure I filled up again before 300 Miles.

On the 3rd gen you have to drop the tank to replace, probably the same on the 4th gen. If that is the case, I would have any/all gaskets replaced along with the fuel pump.

In my case, I dropped the tank and replaced the sending meter. Then a year later I got an Evap code...so I had to drop the tank AGAIN to fix and I just replaced most everything including the fuel pump because dropping the tank isn't fun.

 

Thanks so much for your help. I think l will use the trip meter method

 

I would replace the fuel cap before dropping the tank.

I had the same issues with my 2007 FJ cruiser and my 2013 5th generation, which are close relatives of your truck.

 

How does changing the fuel cap fix a bad fuel sender?

 

The fuel system runs on a vacuum. If the gas cap does not make a good seal then the vacuum will never be created, and the system might not register right. In your case, possibly showing as consistently empty

 

No. The FUEL SYSTEM runs on pressure. The fuel pump creates pressure to send fuel to the engine.

The EVAP system runs on vacuum...and is affected by the gas cap. Is that what you meant?

BUT, I don't see how the gas cap is going to fix a SENDER issue. The Sender is a float setup in the tank which doesn't use either pressure or vacuum.

I provided EVAP information because it will be a problem down the road...and if you are replacing the SENDER...it's worth replacing any of the seals for anything else in the tank...if you have to drop the tank. For my issue, yes, I replaced the cap to try and solve the EVAP code it but it didn't help. OP doesn't have any EVAP issue yet.

 

I’m saying is I had the exact same problem with two similar vehicles and all the problems that you were describing happened, and replacing the gas cap solved it, so unless you are confident that it is a fuel sender issue, I would replace the gas cap first.

 

https://www.ebay.com/itm/323959169934?fits=Year%3A2007%7CModel%3A4Runner&epid=658609712

This is the sender for a 2007 4Runner. It is a dirt simple device with a float that moves based on the fuel level. The float moves a bar which is connected to a potentiometer (white box) which is read by the gas gauge on the dash (or by the ECU...not sure). No vacuum is involved which is what a new gas cap would play a part in.

The only crazy way I could see a gas cap affecting the sender...is if the ECU is reading the sender and won't send the right data to the gauge if something else is wrong in the EVAP system. That would be outlandish and really bad engineering...but maybe newer cars are that bad?

 

The fuel caps have vents in them which stop working over time, usually from environmental contamination, and will mess with the evaporation system.

On both of my vehicles I was just driving and the fuel gauge dropped down to empty from completely full, but no other warning light came on.

Both times replacing the fuel cap with a new Toyota fuel cap fixed it.

 

Gotta be something else in the mix then. Maybe the ECU is in the equation somewhere. That would be a PITA to diagnose.

 

Update! I replaced the gas cap and the problem appears to be solved! I still 0 out my trip meter just to be safe but everything appears to be in working order. Thanks so much for all of your responses.

 

Whelp. Lesson learned.

 

Chalk one up for @LandCruiser.

 

Yeah, good call by him.

I'd still like to know HOW a fuel cap screws with the fuel sender though? It's literally the simplest system for measuring fuel level but somewhere it's in some way connected to the gas cap by way of the evap system.

 

This guy knows the facts! The electrical thing attached to the float can become oxidized and not make the variable electrical connection to vary the needle on the gauge!

I had a car one time if I didn’t run gasoline w Techron the the dash gauge wouldn’t work right….. had been buying cheap gas.

Keep the 300 mile range in view but try a top tier fuel for a couple of tanks to clean up the fuel system!

 

Hello there,
New member here. I have a similar, but different issue. 2004 Sport V8. Fuel gauge on cluster reads empty, the gas light stays on constant, as well as the Range remaining on the digital display with the clock also says zero(0) miles. I've been using the trip A meter and resetting every fill up.
Not sure what may be causing this - possible electrical issue since both are affected? Mice chewed the wires? Fuse? Any help and suggestions are much appreciated. Thanks in advance.

 

Sorry for double post, but... did some research, took the back seat out above the access gas tank, and found the wires were indeed chewed to the 5 pin connector going to the fuel pump. I resoldered those, and everything seems fine now. Cheers.

 

I had this happen on my 09'. I dropped the tank and replaced the potentiometer that also has the float attached to it. Not a hard job at all. Only took me about 4 hours start to finish and fixed the problem. I think I paid just over $100 for the part from Toyota.