noboostnogo

iTrader: (4)

I figured i would try and put something together for whoever is interested. I did this mod in my garage with basic hand tools and some common sense. I am sure there are many ways of doing this and alot of you guys will ask why not a sumped tank and an external fuel pump? well couple reasons, this is more affordable, no need to custom mount a new tank, its as quiet as stock and will work with the factory fuel gauge sender unit. This is my first time doing a write up so please bare with me and ask questions if something is not clear. Please remember that this was not my idea and i did alot of research before performing this and asked other members on here for help so thank you guys very much for helping me out.

Here we go!

Step 1)
Drop the rear end and lower the fuel tank and set fuel tank some place where you can easily work on it. Please use common sense and remember this is gasoline and could/will easily go boom.


Step 2)
Before removing the stock sender unit make sure you clean the area around it to get rid of any dirt dust etc that might get in the tank. Remove the big round piece that hold the unit in place. Notice how there are 3 or 4 tabs, i used a flat head screwdrive and a hammer and it easily came off.Counter clock wise will get it off.

Step 3)

When we look at this picture we see 4 lines. Line number 1 is a 3/8" fuel feed line. #2 is a 5/16" fuel return line. #3 is a 5/16" evap line and #4 is a 3/8" vent tube.

This is the main step of the set up so read closely. I picked up some fittings at a local shop for this mod.

The -8an 90" elbow is gonna be our new return line. The Yblock will be what connects the two fuel lines into one and the other fittings are 3/8" tube to -6an adapters.

Cut lines number 1 and 4 at a desired length. I chose to leave about 3-4" of line and then put the line adapters on. Once done with the line adapters cut and drill out line number 3 i used a bit big enough for my -8an 90* elbow but you could use a -6an elbow instead depending on application. Notice the teflon washer to keep it nice and sealed.

Here is a pic of the back side.


Now that we are getting our hands dirty with cutting and drilling grab a small drill bit to drill a small hole to run two wires through it. More details in step 6

Step 4)
Now that we have our outside lines ready its time to mod the inside lines or should i say line. Before cutting any lines (this is up to your skills) you want to weld 2 supports from the factory feed line to the factory return line to keep it from moving. What i did is put some submersible fuel lines in between the two lines (factory feed and factory return) and clamped the two together instead of welding supports. Once the lines are nice and tight cut and take out about a 1" gap from the factory return line which is number 2. This will now be our new vent. The welded supports or clamp is to keep the lines from moving since they are pretty flimsy after you cut that line.

Step 5)
Now that we have our lines done its time to mount the fuel pumps. I used 2 walbro gss340 Whatever fuel lines you use make sure they are SUBMERSIBLE SAE 30R10 or it might cause problems down the road. I used gates 5/16" submersible fuel line which i picked up at Napa for about $28 its part number H209. I cut a 2 1/2" piece for the 1st fuel pump which is in the factory spot and the rest i used it on the second pump to line number 4. Make sure you use clamps on all line ends.
I had about 8" of -8an stainless steel braided line which i used as my return



I used the factory fuel pump rubber jacket as a spacer between the two pumps and then used some hose clamps to clamp the two pumps together.

Step 6)

Time for wiring. Remember that hole that you made in step 3? well thats the one that you will use for the new fuel pump. Make sure you install a small grommet on the hole and run both wires through it and once in place follow w/ some GOOP to seal.


Step 7)

Install both pumps back in the tank. this is going to take a couple tries and will require you to do some thinking.
I took some fast measurements and the third gen tank hole is just as big as two walbros side by side so this will be TIGHT.

Mine got stuck on the clamps at first but then it just went in.


i went ahead and ran the two -6an lines to the y block and placed it where the factory tank fuel lines meet the factory body fuel lines.


Make sure you put that big thing (i think is a one way valve) on the end of the new vent tube.

I ran -8an feed thru an inline filter and -8an return line. Also make sure you run another relay for the second pump and a boost activated switch like a hobbs switch so that it is not on at all times.

This dual intank walbro was been proven to flow enough fuel for over 1000hp

NOTE: If you have emission test this dual walbro mod is not the right one for you.

Hope you like it and i want to hear your feedback

//<86TA>\\

iTrader: (14)

good right-up, but does that -8 90 on top of the tank clear the floor? looks like it wont or it will be really really close

noboostnogo

iTrader: (4)

yeah it cleared it for me when i installed the tank back on

83 Crossfire TA

iTrader: (2)

Why, what's the problem with using this setup for emissions?

If those hardline adapters are what they look like they are not designed for use on steel hard lines.

Orr89RocZ

iTrader: (20)

This setup deletes the evap line I do believe so you dont have a working charcoal canister.

noboostnogo

iTrader: (4)

yupp.

There is a crimp piece in there that is not pictured. It is a 3/8" line to AN adapter.

Pocket

iTrader: (24)

They're not rated for EFI pressure. On return lines, its ok, but TPI/LTx/LSx engines require more than those can support. Two more bulkhead fittings and it should be ok

Hope you used submersible EFI hose for the secondary pump. The stuff you get at a parts store will dissolve from the outside

noboostnogo

iTrader: (4)

i have a blow thru carb'd motor. I dont understand what you mean by two more bulkhead fittings and it should be ok.

I did use submersible fuel lines, i posted the part number in the first post. It was a gates line SEA 30R10 or something like that.

Pocket

iTrader: (24)

Carb pressure is A-ok with those connectors. I think the rating is 25psi or something like that

The 90* fitting you have with the teflon gasket is a bulkhead fitting

noboostnogo

iTrader: (4)

were you reffering to the two feed lines? replace those with 2 90* bulkheads? i thought about it but then my gauge sender unit wouldnt have worked.

//<86TA>\\

iTrader: (14)

im not sure where people come up with these pressure ratings, but compression fittings are also using in household plumbing applications and can easily hold 80psi.

88gta3508

why would you waste your time with a intank.. mod..dual pump.. when they both will die
in less then 2 years.. delete the intank junk and install a external Pump

Orr89RocZ

iTrader: (20)

i've had mine for 3 years and no problems. Stock one which never failed was in the car for 20....

88gta3508

thats a first I have yet to see ANY after market intank pump live for more then a year
if you have in the 350 - 400 HP range.. if yours lasted that long there is no way you drive your car.. very far

Twin_Turbo

iTrader: (25)

But not all are made equal, this is an aluminum body with a brass ferrule on a steel line. How much crushing pressure do you think you can get before stripping the threads? It's all about the crush sleeve biting the steel line. The max rating on those is around 50PSI but that is under ideal circumstances. If there's anything that will affect the ferrules bite on the line you have a problem and guel is not something to clown around with. If unsure get some swagelok stainless ones. They are expensive but rated for much higher pressures. I've been saying it on these forums too, use those fittings only for carb or TBI applications and maybe trans cooler lines. Don't be surprised if your EFI lines leak when using these.

anesthes

iTrader: (12)

Usually the problem is either bad parts, or bad mechanic.

I've used in tank pumps on much faster cars than 400hp for many many years.

-- Joe

88gta3508

thats the story bad mechanic.. replacing a fuel pump.. ARE you series.. wow i think i have herd it all in here... one pump I can tell you for a FACT is universal master external..myself and 2 buddy's. they all died in less then a year.. more then once..
I have much more then 400HP as well.. I installed a holley projection pump I made a couple of full throttle runs It died... 2nd pump.. the original i'll blame on age...but it had little use
I have a afr meter and a FP gauge on board never left 45# and dropped to Zero..
I'm absolutely positive it was bad parts..

noboostnogo

iTrader: (4)

Hey man i understand that you dont beleive in in-tank fuel pumps but thats your opinion thats it. This is not a thread to compare and contrast, but instead to help someone out who is looking to do the mod. If you read my first post i asked for feedback on how to improve this mod or what could get changed if you dont like this you dont have to click on its as simple as that. Mannnnnnnnnny people are using aftermarket in-tank pumps with great success not just on this forum but all over the internet maybe you and your buddies got the lemons or didnt use the right fuel regulator.

88gta3508

your right.. I'll stick with my aeromotive external pump.. no need to drop the tank, drop the exhaust, shield, panhard bar.. life is good!!! we did all have Holley adjustable regulators..that must have been it..
I must say you really did a nice conversion... - an lines.. the rubber hose in the tank I would not do. but the rest excellent job!!!

anesthes

iTrader: (12)

I'm no series, just one guy but I am quite serious. When I owned a shop, I had replaced pumps that owners "just replaced".

While replacing a fuel pump is quite a simple task, people tend to ignore things like replacing the strainer, replacing the fuel filter at the same time, etc.

I've run Walbro pumps in my, and in customers cars for a decade and never had one fail. Ever!

I'm not quite sure what to tell you.

-- Joe

anesthes

iTrader: (12)

True. I'd hate to have some kid search this thread in a year or two, and think something is defective with in-tank pump design, when they have been used in millions of cars successfully.

-- Joe

whitedevilTA

iTrader: (8)

Don't run your tank on empty and they won't die

But honestly I had a walbro 255 in my old cammed TPI setup for 3+ years...not one problem with it. Took it out and after it sat in the garage for 2 more years, we put it in an IROC that we sold and it's still going today.


And to the OP, nice write up. My brother is doing dual walbros in his stock 3rd gen tank and this will give us something to go by!

Kory-88Iroc 350 tpi

iTrader: (1)

Nice writeup. looks like I'll be adding a second pump to my tank over the winter. this will be a good referance. btw I've had a walbro pump in my Iroc for 11 years. car is currently about 440 whp. never had any problems.

Blownz28man

iTrader: (2)

Nice write up. I don't blame you on running twin in tank pumps. A ran 1 external one time and wasnt pleased.. Loud as hell. Internal pumps are suppose to "last longer" due to the cooling effects of the fuel. As well as noise suppression.

83 Crossfire TA

iTrader: (2)

I keep wondering about if there is a real advantage to running a line down from the return fitting... what does running a line down from the fitting towards where the pumps are mounted really get you besides the extra hassle of finding some way to run something through the bulkhead and to connect the line to it?

FSTFBDY

iTrader: (33)

No bubbles of the fuel from just dumping the return back in from the top.

customblackbird

iTrader: (15)

I heard the same thing about the hardline AN adapters not being able to handle pressures higher than 25psi... which i can tell you from experience that they will seal with a walbro 255lph HIGH PRESSURE pump running close to 50psi at the fuel rail.

Im currently still running my walbro 255lph high pressure pump but now on a 521 BBF carbed application and its still working, been in the tank for 2 years and im upwards of 550hp and even more tq. I like the dual intake pumps for that stock look and its not that hard to do from the looks of it. But Im going to be doing a fuel system upgrade and when i do Im going to sump the stock tank and run alot of pump and large -8 to -10 lines.

Pocket

iTrader: (24)

Getting away with running it at that pressure doesnt make it safe

customblackbird

iTrader: (15)

there are alot of things that ppl run and they work but it doesnt make them safe. I dont like anyone who puts rubber hose over hard line with clamps, but im sure alot of ppl do it and it works but is it safe? compression fittings are used all the time for various things and parts are usually rated conservatively anyway. I dont think you would have a problem with hard line adapters on fuel injection depending on how the fitting and line are prepared and how good u get the ferrule to seat into the tube.

Sojer

I know its old (should be happy im doing my homework)
What fittings would be good for LSX applications?

neilb

This is a very good write-up! It's something I am considering for sure, but wasn't sure if everything would clear and function properly. Thanks for clearing things up. My only question would be the rubber fuel line that's submerged, could it be replaced with nylon line or braided line? In a carbed application like yours it would be fine, but I'm wondering in a EFI setup running higher pressures if a problem might arise?
Also, could you post a clearer pic of where you welded a support? I'm not quite clear what you did there.

On the subject of in tank versus external... while I have no personal experience with external pumps, I have had plenty of experiences with internal pumps, and the #1 reason pumps fail is people let their tanks run too low too often, internal pumps need the fuel to keep them cool, run the fuel low, and the pump overheats. The #2 reason is improper voltage to the pump. Factory wiring is not sufficient for an aftermarket pump, too much voltage drop across the small gauge wiring. A fuel pump hotwire kit or a complete harness is almost mandatory. #3 reason (not usually a common problem in the performance market) poor maintenance, ie filter replacement, poor fuel grade etc.

Thanks again for the great write-up!

*edit* I just realised this was an older thread!! haha, still a good one though!

Pocket

iTrader: (24)

I drew up a complete system diagram in the additonal info thread in the LS1 swap sticky for single in-tank pumps on EFI senders. If going dual or other high performance return style, check out my unsupervised thread in the LSx forum. I go over two complete fuel systems, the latter a hobbs switch activated dual in-tank kit

If you are following the OP's design and cutting the sender lines back, use a tube nut/sleeve and flare the ends of the lines for a proper fitting rated for the pressure

Almost all braided SS line is common EFI hose sheathed in SS, non-submersible 30R9. If you have a scrap section laying around, strip the sheath off and read the SAE rating. The SS sheath is not water tight and will allow uncoated rubber lines to dissolve

30R9 is EFI hose that cannot be submerged
30R10 is teflon coated inside and out and can be submerged

Its also a good idea to look for the rating on any fuel line included with the pump kits. Aeromotive 340's all come with non-submersible line with their in-tank kits, along with hose clamps not rated for high pressure too. FYI, dont ever buy a 340 pump

External pumps have the same life expectancy as in-tank units. Just dont run the exhaust right next to them

The two main reasons for pump failures are from being 20+ years old and cheap knockoffs. Good pumps last a long time, keeping them submerged in fuel helps, but running low is expected in the life of the pump. Look up external pumps, they're function is just like an in-tank setup perpetually running on empty. If you compare the pumps, you'll notice the difference is the connector type and in-out fittings change

The factory 16ga wire is sufficient for most applications, even the common walbro 255. Pushing a setup or upgrading to twins should warrant a look at the amp draw of each pump. Often, they do exceed the factory wire, but it is not a blanket situation

89gta383

iTrader: (5)

I can't see the pics??? I need to make this mod. Someone help?

Matt87GTA

15 years and counting with my in tank Walbro 255lph...

Matt87GTA

I put compression style tubing nut adapters on my factory hard lines under the hood that convert to 6AN for feed and return to my fuel rails that were already 6AN. Probably looking at about 12 years on that setup with no leaks. I don't think they are a problem if you do it right.

topless87

I would go ahead and do a fuel pump rewire is the only thing I see that would be different. Pumps flow quite differently under less than ideal voltage is why I would do that. Other than it, the article is a nice write up. I have a similar write up that has the pumps hot all the time and uses a ground to activate them through my Engine Management System, and also activate the second pump. It is in a different forum though. Good article!