Fuel Tank Over Flow Line Leak DIY

Had a couple of evap codes pop up suddenly. Truck runs fine and was going to get to them this weekend. Filled up my tank on Monday morning and fuel came pouring out of the top of the tank (not the filler neck cap but on top of the tank). Had some internal dread that the charcoal canister cracked. Investigation found that a short segment of ~1/4"ID line had a couple of large holes. The offender is the overflow line from the top of the tank that connects into the filler neck assembly. Toyota does not sell this line on its own. You have to buy a tank assembly @~$800.






I made the repair and will post some more support pics to show where this is under the truck and what could be done to fix it for about $10 and an hour. Disclaimer: this is not an official solution as it does not use Toyota parts. Perform at your own risk. Ymmv.

What you need:
Something to cut the hose at the bad section. I used pex/PVC pipe cutter as it makes a clean, straight cut.

2 of 1/4" nylon fuel hose barbed fittings. I would not use brass. You could opt for stainless. I used nylon because the line itself is nylon

1 length of 1/4" ID fuel hose. Don't use vacuum line or heater hose or vinyl. Those will rot.

Drill with variable jaw chuck. This is how you will efficiently spin the barbed fittings into the nylon line. Nylon needs a little heat to make it workable. The friction of the fitting being spun on the ID of the factory nylon lines makes it much easier to get these in.

Patience.

Step one. Locate the leak and cut back below the bad section leaving you with a good section (no holes) of line left on the tank. Make sure it is long enough accept a fitting.

Step two. Remove the line at the filler neck. Simply pull up the guard clip and press in on the retaining clip tabs and pull line off.

Step three. Remove the line. You will have what looks like the first image.

Step four. Cut out the bad section. I chose to cut out the entire corrugated segment. This makes it easier to get fittings that fit right.


Step five. Insert nylon fitting into remaining section of original line that you removed from the truck. Put your nylon fitting in your drill chuck and lightly tighten chuck just enough to have a firm hold. You don't want to collapse the fitting but you don't want to be too lose such that the drill chuck jaws slide on the fitting. The goal is to use the drill to spin the fitting into the tube. The friction of the nylon fitting spinning against the ID of the nylon tubing will generate just enough heat to insert and once the tubing cools it shrinks over the barbs and will be sealed.

Step six. Repeat step five for the other remaining but of line attached to the tank vent.

Step seven. Insert rubber fuel hose to open end of barbed fittings on the tank and uncoil excess over the frame along original routing.

Step eight. Reinsert the free end of the original fuel line at the filler neck (the clipped end).

Step nine. Line up fuel hose from tank with fuel line from neck cutting excess length and insert onto barbed fittings to complete the joint.

Step ten (optional). Wrap with thick tape. I'm my case the reason this thing failed is the line came out of the clips and rubbed on the frame rail until a hole opened up. The clips are 13 years old at this point and have seen 100k miles and a decent of extreme temperature (-50 with wind-chill to 112 air temp). The thick tape should be a decent barrier to prevent direct rub on the new tubing.

Step eleven, snap the line back into the clip and optionally add a zip tie or three to keep the new line up off the frame rail or restrained enough that it cannot move.

 

Geez. Can't tell if that is just abrasion or chew marks. Did you see the cause under there? How many miles on your truck?

Thank you for the heads up and an easy fix.

 

Abrasion I think. The width between the two primary locations is exactly the width of the frame rail. Could be chew marks though. I am still chasing an issue with my 4wd that was the result of mice trying to do wiring. You'll also see another post where I found a nest in the relay/fuse box under the hood. Either way fuel line is fixed. Now my battle is keeping mice out and figuring out what has my 4wd in fail safe mode. The truck has 100k on it now. I don't drive it much anymore, hence the mice moving in. My only issues with this truck are rodent related. Parking outside for the last 3 years with a bounty of nut trees and a drainage ditch within 15' makes my truck look like a lavish hotel for critters. They don't even have to get out into the open to gather a nut or two. Short of a snake or a house cat, no predator to get them.

 

You can see they don't have travel outside the shadow of the truck to find food. This was last fall. The trees have produced more nuts this year and I have to get the leaf blower out every other day to clear the driveway of food sources. Getting the garage reorganized so she can sleep inside again.

 

JibbaJibba56 I am a new member and I am having same problem with return line. My 2015 Tundra only has 47000 miles and dealer has already changed fuel tank once at a cost of little over $1500 dollars. The problem is back again rodent problem. Two questions 1 how did you get to top of tank or did you drop tank? 2 Where did you get the connectors used and if you have a part number. Great post looking forward to reply THANKS
GWB45

 

The nylon barbed fittings are just 1/4" ones I had on hand from rerunning fuel lines on my project car (90 VW Corrado). The hose I used was just Souix Falls reinforced fuel hose I got at Menards. You can buy nylon fuel hose from Napa and heat it a little with a heat gun on low to make a bend. You could use 316L stainless barbed fittings but I figured nylon would be less likely to cause the line to sag from weight.

I didn't need to drop the tank. I put down cardboard behind the rear door leading all the way to the rear differential. You can crawl under there and prop yourself up pretty decently to do the work. Plenty of clearance. Just need to work around the hoses going in and out of the evap canister. If you have a recurring issue you might try putting a length of aluminized exhaust fabric over it. I know rodents prefer not to chew on things that stab there gums or make their tongue itch. It looks like the silver part I am holding (this is the heat shield for wires and a brake line in my project car. .I bought this on rock auto. Just generic hose/wiring heat shield).

 

Thanks for the quick up I'll try this going to try to get rid of the squirrel too. THANKS AGAIN

 

My index finger is pointing to the repaired line. That is the amount of room under the bed/above the tank so it is manageable. I was slightly tempted to take the bed off to see if the vent itself can be taken out of the tank but my rhino liner is overtop my bed bolts. On Ford's the tank vents used to be two winged quarter turn type of thing and not hard to get in or out. I couldn't get it to budge from under the truck.

 

Thank you so much for the post, dealing with this exact thing on my Sequoia today! Just to be clear, you used a 1/4 nylon coupling like this one: https://a.co/d/2xiqvYS or this one? https://www.ebay.com/itm/261387859679

 

Both should work although the second one you may want to as a hose clamp as it has no added barbs. First one is more like the ones I used.