Fuel Tank Baffles

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rocketscience
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Fuel Tank Baffles

Post by rocketscience » Mon Dec 10, 2018 10:31 am

Can anyone confirm that our tanks have baffling in place? I read a post from Synthdesign's 4age swap were he mentioned it but my car is an 83 so I'm wondering if it might be different. I'm about to try the Denso Tbi swap and was planning on using an inline pump. I am wondering how much I'd need to hedge against fuel starvation on steep hills/turns etc. There's quite a bit of fuel in my tank that I need to burn up on errands so I haven't looked for myself yet.

I'm aware that I could use a corolla gt or 88 nova twin cam fuel sender but have had a hard time finding a used one and I don't want to drop hundreds just on the fuel pump setup for a NOS one. If anyone has leads on any I'd be interested.

Don't worry, I'll make a big post on here when I get it together.
Last edited by rocketscience on Wed Dec 12, 2018 9:44 pm, edited 1 time in total.

rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Wed Dec 12, 2018 12:13 am

The bad news is that there are no baffles, at least not in my 83. Good news is that the tank looks fabulous inside, very clean.

I've looked into a few different options:
1. just running it with an inline and nothing else
2. add a low pressure external lift pump in front of the high pressure with a big spin on filter (which I have already) or surge tank before or in-between
3. similar to #2 but just use the stock mechanical pump and put the efi pump in the engine bay

3 may be the most simple but it adds more parts and extra noise to the engine bay. it'd all probably be on the exhaust manifold side too which might not the best idea.

Its not like its a race car and I'm pretty easy on the gas so I don't know how big of a deal it will be.

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Re: Fuel Tank Baffles

Post by The Professor » Wed Dec 12, 2018 8:13 am

I would definitely consider adding a surge tank with an EFI-rated fuel pump all being fed by the stock Tercel pump.
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rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Wed Dec 12, 2018 10:18 am

The only other downside to that setup is that I think you'd still need a larger return line to the main tank which reduces its simplicity. Maybe you could use the vapor line?

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Re: Fuel Tank Baffles

Post by Petros » Wed Dec 12, 2018 9:20 pm

our Tecel tanks do not have baffles, neither do the EFI corolla tanks as I recall. if you can get a corolla fuel pump assembly, I am pretty sure it will mount in the Tercel fuel tank, the flange is the same. You would need both new supply (high pressure) and return lines. I think most people who switch from carb ro EFI just add an efi pump under the hood since it is easiest to adapt.
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'84 Tercel 4wd (daily driver, with on going mods)
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'85 Tercel 4wd DLX auto(daughter's daily driver)
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rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Wed Dec 12, 2018 9:54 pm

Petros wrote:
Wed Dec 12, 2018 9:20 pm
our Tecel tanks do not have baffles, neither do the EFI corolla tanks as I recall. if you can get a corolla fuel pump assembly, I am pretty sure it will mount in the Tercel fuel tank, the flange is the same. You would need both new supply (high pressure) and return lines. I think most people who switch from carb ro EFI just add an efi pump under the hood since it is easiest to adapt.
I've been looking for a corolla gt 85-87 pump assembly, i had found that it, the 88 nova and maybe the fx 16 would work. I'd been trying to read about it on one of the other toyota forums. Would other corolla's work?

The metro/swift throttle body has a 5/16 supply and 1/4 return, I was going to run a 5/16 line and use the stock supply as the return, its fuel pressure should be pretty much 0 anyway. The metro fuel pressure should be between 24 and 33 psi so it isn't very high. The pump I have puts out a little more than that but less than 50.

Do you mean most people retain the mechanical pump and add an efi pump in the engine bay? I was under the impression that the efi pumps do not like to pull fuel very far, they should be as close to the tank as possible and as low as possible if no other pump is used. I've also never done this before so I'm just learning as I go.

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Re: Fuel Tank Baffles

Post by rocketscience » Thu Dec 13, 2018 10:24 am

Eh, I'm just going to put the inline pump at the back with a big spin on filter up front where the stock one is, that should act as some kind of buffer. If the tank isn't baffled it shouldn't make much difference whether the pump is in there or not, it could suck air just as easily, and it will be a whole lot easier to change if/when it fails. I've read it's good to keep it close to the tank and low so that it's more of a gravity feed.

I have the TB adapter, harness, vss, check engine light and fuel system stuff ready to go, I just need to make an adapter for the stock air cleaner today and I'm ready to try it. I was very tempted to throw it together today and tomorrow before I drive to MT but I think I'm going to wait and do it there next weekend. I've been taking lots of pictures and making diagrams so when I get it put together and test it I can share with everybody in a way that should be easy to replicate. It really shouldn't be too hard, I'm very excited to attempt it!!

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Re: Fuel Tank Baffles

Post by Petros » Thu Dec 13, 2018 4:43 pm

Rocketscience,

sounds good. how much has all that stuff for the TBI conversion cost you so far?

if you take the time to take pictures of each step, and than organize and post them in a new "repair guides" thread, you can provide a nice tutorial for the rest of us.

you want to see a nice example, see my "brake upgrade" thread. I used to work at an aerospace company writing repair and retrofit instructions for commercial jets, and have learned how to get information across.
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Re: Fuel Tank Baffles

Post by teranfirbt » Sun Dec 16, 2018 10:27 am

When I fuel injected the 3AC I ended up with a surge tank in the engine bay and an EFI pump off that. I used the stock 3AC feed and return lines and never seemed to have any trouble. The EFI pump pulled and returned to the surge tank, so I wasn't trying to push any pressurized fuel back to the main tank, only the return from the carb pump.
For my current 4AFE setup, I kept the same surge tank but switched the feed pump to an electric carb pump that's mounted back at the main tank. It pushes through 5/16" tube to the surge tank in the engine bay and returns through the original 1/4" carb pump feed line. I haven't had to think about it for awhile, which means it has been reliable (so far...)

rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Mon Dec 17, 2018 10:59 pm

teranfirbt, thanks for the info, the surge tank in the engine bay would have to be the fastest way to do it but I'm still tempted to run the pump in the back just to minimize the amount of stuff in the engine bay and make it less dangerous if I run into a deer or something. I was just looking at your CBR600 setup, pretty dang cool. I think I'd seen that before but missed that you'd put a trigger wheel and wasted spark setup on it, that's something I want to do once I get the swift efi working. I'm planning on using an arduino speeduino ecu in a swift/geo ecu case with the swift wire harness.

Petros, I'm definitely planning on making a tutorial in the repair guides. I have lots of well labeled photos and documentation that'll be in there, and I'll probably make a pdf version as well so its easier to print and share. It probably won't be exactly how everybody will want to do it but should be pretty helpful. I bought an 89 meto FSM so I can post anything out of that too.

Its cost me around $300 sourcing most parts from junkyards. You could do it for less. You could probably buy a whole metro for that much haha.

I did decide to wait until after this road trip to do the conversion, around the beginning of January.

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Re: Fuel Tank Baffles

Post by Petros » Mon Dec 17, 2018 11:22 pm

Teranfirbt,

Sounds like a good set up, simple to adapt, I might use that on my own project EFI/4age swap conversion.

how big of a surge tank did you use, where did you get it? can you post a picture of the set up?
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Tue Dec 18, 2018 8:01 am

Heres a $300 metro https://seattle.craigslist.org/see/cto/ ... 77293.html

Oh, just noticed its an auto. The ecu is almost the same but you'd have to make a couple wiring changes.

Another one :) https://seattle.craigslist.org/see/cto/ ... 63067.html

rocketscience
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Re: Fuel Tank Baffles

Post by rocketscience » Tue Dec 18, 2018 8:12 am

Mk2 vw's used an EFI fuel pump inside a little surge tank with a fuel filter mounted to it. I'm sure you could get one from a junkyard for less but heres a listing with a picture: https://goo.gl/Whmj5C.

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Re: Fuel Tank Baffles

Post by rocketscience » Tue Dec 18, 2018 6:59 pm

I was reading on another forum that people also had success using a very big spin-on diesel style fuel filter before a carb pump, just like the stock filter, with the efi pump after the carb pump. The carb pump can prime and pull fuel into the filter which acts as a surge tank.

I already have a big filter with a filter base that has 2 inputs so I can run the efi return into that, it should be super easy and I can put the big filter down where the stock one is so its more out of the way and work with the stock line routing. I'm also gonna put a smaller filter after the efi pump.

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Re: Fuel Tank Baffles

Post by teranfirbt » Tue Dec 18, 2018 7:12 pm

I made my own tank from flat aluminum sheet, it ended up around 1 gallon. If I did it again I'd get one from ebay that's premade in the ~2 liter range, a gallon is silly. Something like this: https://www.ebay.com/itm/2L-Fuel-Polish ... rk:18:pf:0

For an EFI pump I used the stock pump for an '83 Celica, but I replaced the outlet fitting with an M8x1.25 x -4 AN fitting and plumbed that to -4 AN fuel hose.

I'd be worried about a big filter not feeding the EFI pump correctly, since the EFI pump would be trying to pull from the top. If you flip the filter over it would just be a big air bubble... You'd really want a tank that you could pull from the bottom into the EFI pump and run your EFI return to the top, then keep that topped up with a carb pump, either the stock 3AC pump or an electric on, that returns to the tank.
With the big filter if you punch a big air bubble into the top, your EFI pump will have nothing to pull but air.

With a surge tank it's less critical that the carb pump be always primed, pushing an air bubble into the top of your surge tank doesn't affect the EFI pump as long as you get fuel back before the surge tank drains down. Returning the EFI pump back to the surge tank makes this a lot more practical too.

2nd gen Nissan Maxima fuel filters are easy, they have 8mm (5/16") barbs on each end and are fairly compact. Make sure you get the correct high pressure EFI hose and T-bolt style hose clamps if you do any barbed connections in your EFI system. Worm gear style clamps are definitely not legit, and the 50 PSI rated fuel hose is likely to burst at EFI pressure.

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