Fuel tank issue

Hi all! After replacing the straps on my fuel tank on my 2004 Tundra, my fuel gauge stops working at the half mark. When I fill up, it goes to full but after driving it just stops at half a tank. I did have a hard time getting the tank back up and may have jacked it up too far.

 

Sounds like you either damaged or got the sender unit in the tank partially stuck. I don’t know enough about it to say if it’s an easy fix or not.

I’d probably look up in the Field Service Manual (FSM) what’s the way to test it to see if it’s still good and if it was installed incorrectly. Probably your best bet unless someone else can chime in on a simple method to check it.

 

Jack already alluded to this, but two things to elaborate on.

First, the fuel level sender is integrated into the pump assembly. You can buy the pump alone when replacing, or the entire assembly. The senders will sometimes go bad (corrode) with time, exposure to oxygen or water. The slide part of the resistance-based circuit will oxidize and have “dead” spots when the float on the assembly gets to a certain height. Sometimes the sender just naturally goes bad. It happens.

Second, because the sender is part of the pump assembly, it means the sender wire itself is in the harness that attaches at the top of the pump. Thus, if you potentially smashed that harness or mangled it in someway, and the wire is getting pinched in certain situations, that could cause the circuit to have no resistance, i.e. the gauge would read zero. I don’t know if the weight of the gas tank based on how much gas is in it would cause a pinch or no pinch.

Third, it’s a known problem that rodents love to chew on wires in this truck, and under the V8 manifold and on top of the gas tank (and the gas filler neck) are very notorious spots.

What you need to do is fully verify your tank wiring harness starting around the rear of the driver door along the frame rail, up to the top of the tank, especially anywhere it could get crushed or pinched. Then take a mirror and light and verify on top of the tank, all wiring is fine and the top of the pump assembly didn’t get damaged. You can also tap into the circuit with a DMM set to resistance/ohms, and check how much amperage is on the circuit to check if maybe the sender is bad.

However, full disclosure; if my truck had more than 150k-200k miles on it, I’d consider that a good lifespan for the fuel pump assembly. In which case I would spring the $$$ for a replacement assembly. If you gave me more details about your truck, what engine, what cab type, what drivetrain (2WD/4WD), and which trim (SR5 or Limited or ??), along with your city’s typical telephone area code; I can run down the OEM pump assembly part number and cheapest legit place to buy it nearby and online, since you DO NOT want to go non-OEM on this specific part, and you NEVER buy auto or appliance parts on scAmazon or fleaBay because they’re chock full of knockoffs/counterfeits, of which you have no recourse if you get screwed, and some are extremely convincing knockoffs. You DO NOT want to do this job twice, and OEM lasted this long, it will last another 15-20 years too. There isn’t an aftermarket part on today’s market that can make that claim!

 

PS - link to the FSM and wiring diagram for your truck is on the 4th or 5th line of this post: https://www.tundras.com/threads/so-you-wanna-buy-just-bought-a-1st-gen-tundra-eh.115928/

I would grab the 2000-2003 FSM for you. It’ll best match your 2004. In 2005 they introduced SAIS and other changes that don’t match your vehicle.

 

Thanks guys! I figure I probably damaged the sender unit while jacking it up. I’m gonna run most of the gas out and drop the tank…again. Thanks for all the input. I will post my findings!

 

Awesome, LMK if you need part numbers!

 

My truck is a 2004 Limited, access cab, 4WD, 4.7L. Area code 828, city of Morganton NC

 

Part numbers would be great Shifty!

 

Ok, this is cool, I haven't had to do a 2004 V8 Limited yet.

So, here's the thing. It looks like in your case, you're a lucky dog and you could just replace the sender BUT ... there's a bit more to say after the part numbers.

The sender part number for your truck appears to be 83320-34050
The entire fuel pump assembly part number is 77240-0C051

Here's the weird part. The exploded diagram doesn't show the fuel sender as including with the assembly. But when I look at part numbers online, clearly the sender w/float is visible on the part, so it seems to be included?!

Anyway, the only reasonable priced parts source I found to Morganton using the national parts stie is in North Charlotte, specifically this dealer. (that link goes to the entire assembly). Sadly, Modern Toyota of Boone and Flow Toyota of Statesville are both money-hungry assholes and don't offer you any discount when ordering thru the national parts system, so they're charging almost 50% more for the part. What a buncha dicks!! Toyota of Greenville offers the same whopping discount North Charlotte does, and Hendrick Toyota of Concord is about 10% more than those.

If this were me, I'd really want to talk to the dealer to confirm 100% that the sender was included in the assembly (77240-0C051) before buying. If you don't want to order online, then drive to one of the dealers mentioned to pick up the part, this dealer is who I like to use in Alabama, because they do free shipping over $75, AND they don't charge tax. Not to mention, the part is about $10-15 cheaper with them.

Of course, if you don't have the coin, or don't want the risk, and only want to swap out the sender, go to either of those "this dealer" links above, and plug in the sender part number (83320-34050) then order that instead... but it's like $190 for the sender only, versus $360 for the entire assembly, so .... I'd recommend verifying your wiring first, for the sender. A link to the wiring diagram is the "So you just bought a 1st gen Tundra?" sticky thread.

But yeah. Call a dealership. Ask if the sender is attached to the assembly. I'd buy the assembly if it is included.

 

Thanks to Shifty, I was able to get the fuel suction tube assembly for $272! It would have been over $500 with shipping etc. ! I really appreciate the info!

 

To follow up, after removing the old fuel pump, I noticed it was greatly bent not allowing full extension of the float. This must have happened when I was jacking up the tank. Had to knock out the tank dent to get it screwed back down. Thanks for the help guys!