3rd gen 4runner F-150 tank swap behind rear axle

[BruceTS]

I added airbags in the back to compensate, as for the weight shift, there really isn't much difference. The ford fuel pump has never given me a problem and once I drop the tank to adjust the fuel guage sending unit, I'll get pictures of the mods done to it. yea I need to add the fuel filler vent tube, sometimes it's a PITA to get a full tank.

[troyboy162]

just a update on this since its been a couple years. The quick ghetto cradle I went with and always had planed to upgrade, has been fine. I have dropped the tank a couple times and have duck taped cut up sections of the 2" filler hose to anything rubbing. The result is the tank ends up being pinched on the panhard cross member, the bottom of the truck body, and the rear bumper. Shockingly it is held tightly and somehow does not rub much. I expected the flexing of the frame and things to wear into the tank, but the set up is hardly wearing into the duct tape let alone the rubber hose below it. There are much better ways to hang the tank, but so far so good with the quick route.

The problems I have had are with fuel pumps. I have replaced two so far. The junk yard pump was horribly abused during my boil the fuel issues(dont point your exhaust at your tank!), but the other was a high quality OEM pump. The angle of the tank makes the evap vent on top submerged until the tank is 2/3rd empty. I believe the issues come from that since everything else is legit. I think either a vacuum or pressure is built in the tank and the pump can not over come it. I am trying a fancy 255 lph pump to hopefully allow it to work ok...so far so good. Fuel economy has not changed and the factory fuel pressure regulator appears to be fine with the higher volume.

[troyboy162]

updating again. The fuel issues continue. The higher volume pump has different symptoms since its more powerful but the results are the same where the truck needs to sit for a good 30-40 minutes. I have been researching the issue and believe its caused by either fuel starvation at the pick up or preasure issues due to the vent. I also think the new fancy pump has a failed fuel module since the truck can stall at stop signs with as much as 7 gallons in the tank. It just started doing that one day...maybe the extra power isnt a good idea?

nothing seems to be a good fix for the pick up other then maybe a clunk pick up or welding on a deep sump. The tank itself has no baffels internally. origanally I thought that was stupid and the root of issues. In the research I found that ford actually has a pretty high tech solution built into its fuel pumps. So much so that I think I will stick with the stock configuration for the most part. Possibly improving on it a bit for my own unique angled application.
looky here:
FuelDeliveryAssembly2.gif

There is however the issue of the tank vent. I have not confirmed but I would imagine some damage has been done to the charcoal canister since filling my tank full or more dips the vent under gas for a considerable amount of time before enough is burned to uncover it. This guy fixed that issue in the hopes of filling his tank faster, but it should really solve my issues.
http://www.ford-trucks.com/forums/94...ho-better.html

I'm going to throw a new fuel cap at it too since a faulty fuel cap can create all the issues I've had and more.

[Seanz0rz]

That Ford fuel pump is awfully complicated!

Unlike the linked post, I would aim for rubber hose that is fuel certified. I've done some nasty stuff to hoses that were never meant to have fuel in them.

There is also flexible line from McMaster Carr that works well, I will have to track down the specific type though. It is what the VW guys use to replace the vent lines.

I'm not familiar with where it is on the tank, but for the evap vent line could you do a vent on the left rear and one on the right front, and tie them together? This way one is always exposed to fumes, no matter what the angle of the truck.

[troyboy162]

I'm not sure how it would work. I was going to try the rear seeing as thats the highest point on the tank, but then I saw where that guy mounted his at the same hight as the filler neck. No harm in putting it there (although I'll use better materials) and it keeps it so far up the charcoal canister will never risk gas pushed up into it again.

Also I found this if I want to try venting to the air in a troubleshooting effort. You can delet the charcoal canister. I'd rather leave it installed though since I believe it cuts down on your gas just evaporating off like it would.
412071d1230771433-00-tacoma-ext-cab-sas-ts-beta-2.jpg

[Seanz0rz]

Yeah, my 73 VW had a canister, earlier ones did not. The lines end up splitting and leaking. The solution is to move to the older style, where it just drips gas on the ground if you fill up in the cool morning and let it sit in the hot sun.

Also, think about how this will impact the smog check.

[YotaFun]

I don't know about the Cali stuff, but my buddy and I will be trying what I saw on Pirate4x4.
They cut out a square off where the pump and vent of the Toyota tank is and also too out the baffle and then cut a square where the ford pump goes and put the baffle in and welded the section from the Toyota tank to the ford tank, both utilizing stock wiring and venting.
They seem to have no issue, this will not be done till a couple of months but I will report once its done.

[troyboy162]

Thats not a bad idea but if I was to weld I'd just make a bad ass sump closest to the axle. You drill some holes in the bottom on the tank then weld on a square sump on the outside. that way the last of your sloshing fuel drops in and cant get out. I saw how the musle car guys do there tanks when they go to EFI motors with a old style cas tank.

[Kryptoroxx]

I don't know about the Cali stuff, but my buddy and I will be trying what I saw on Pirate4x4.
They cut out a square off where the pump and vent of the Toyota tank is and also too out the baffle and then cut a square where the ford pump goes and put the baffle in and welded the section from the Toyota tank to the ford tank, both utilizing stock wiring and venting.
They seem to have no issue, this will not be done till a couple of months but I will report once its done.

I was about to ask about the same thing. I am however no expert and would gladly pay for that small bit of work to be done right the first time.

Sent from my SAMSUNG-SGH-I727 using Tapatalk

[troyboy162]

Ive learned more....Something that should have come up much sooner lol, but clearly is part of my problem. Apparently the fuel tank preasure sensor is on the stock toyota tank and not on the charcoal canister. So... I havnt had that sensor after tank swap, and thats the part that allows the charcoal canister to actively vent to equalize pressure. Without it I have no idea how the venting would behave but I'm guessing not remotely close to right lol. When there is tank pressure its supposed to sense that and then vent it into your engine when running conditions allow it.

Its really a wonder how it worked at all over these last few years. Also a wonder how other people have been running without it. I would guess I have been floating between vacuum and positive pressure all these years and when I hit a extreme situation the truck gets vapor lock.

The canister is going to be deleted so that I'll be free venting through my remotly located roll over valve. I'll just run it that way in between smogs so long as it corrects my issues and dosnt let all my gas evaporate away in the summer.

Also I'm going to mod the fuel pump a bit to try and keep more fuel in the sudo sump. I'll try to take pictures of that.