Squarebody/LS Fuel pump options...

[ShortHaul]

I know this topic has been hashed over many a time, but things keep changing in the LS swap world, and the "best" option out there today may not be the same one that was popular 5 years ago. Hear me out, and weigh in on the subject if you have any firsthand knowledge.

I am in the process of swapping a 2002 LQ4 6.0L into my '75 C20. The 6.0 is stock, and has the return style fuel rail. My stock fuel tanks are in good condition.

I am looking for insight as to the best option for my setup. I'll list the possible options as I know them...

A. Holley In Tank EFI Module. $383.xx free shipping. In stock now at Holley. Swaps right into place on existing fuel tank. Sender and pump together in one unit, no need for EFI tank. Even has wiring pigtail with proper ohms for stock gauge (which I plan to run) The only hiccup I have is this module is a RETURNLESS style. Meaning its internally regulated and does not require a return line. My current fuel rail is a return style. Also If I want to run dual tanks, the Pollock EFI tank switch unit has return lines on it as well..

-Possible workaround- Run a return line from fuel rail to tank, drill a hole in tank and add return fitting...
OR
-Swap out fuel rail for a returnless style (approx $115)

https://www.holley.com/products/fuel...s/parts/12-308

B. Buy 2 new EFI fuel tanks (1987+ Spectra Part #GM1C) Amazon currently has the cheapest deal, $102.xx with free shipping. Add Spectra fuel sending unit $114.00 from amazon or Hot Rod Fuel Hose, add Walbro 255 pump ($60) (which nobody has in stock...) and retrofit that way. Total cost per side approx $276.00. Cheaper than the Holley route by about $100. Downside is I can't seem to find the correct Walbro 255 lph pumps in stock anywhere.

C. Tanks Inc New tank system with GPA-4 in tank pump. Approx $630 (tank 310, pump 220 sender 40) plus 50 for shipping...

D. Holley Sniper fuel system (comes with tank, sender and pump, basically like the tanks inc setup) $650 backordered till the end of the month.

Option A is the only one I can find that's currently in stock... but poses the issue of what to do with the return line. Also have read that switching the fuel rail to returnless style will make engine run poorly until tuned. (Has start-up tune in it now, plan to do a street tune after all is said and done)

All others are currently backordered at least a few weeks or unavailable.

Anybody have some advice for me? Thanks in advance.

[JJH Jimmy]

I’m cheap so I would go with option B but use GM ep381 pumps which you can get pretty much anywhere.

[ShortHaul]

Originally Posted by JJH Jimmy

I’m cheap so I would go with option B but use GM ep381 pumps which you can get pretty much anywhere.

I'll be darned. Although my quick search doesn't show those to be any cheaper than the Walbro. $82 on the 'Zon, $91 on Rock Auto, $144 at Orielly's.

[kev2809]

i went with option B although i havent installed it yet. but mainly i chose this option for price...AND for local availability. for that just in case thing where something fails, these parts are readily available at local auto parts stores. even if it isnt in stock, they usually can get them same day or next day.

[Joyridin]

I'm not sure why switching from a return style to returnless would make the engine run poorly. You are still delivering X amount of gas at X amount of pressure. The only time I would not run a returnless is if I had a highly modified or boosted engine. I have had both styles on my car and never noticed a difference. I have no clue why you would even have to tune it until you are done with everything.

Personally, I would go with A from a simplistic standpoint assuming your tanks are in good shape. Tanks Inc. has the pump you want and they are 100% genuine, but they are $107 each.

I am installing an L83 in my truck from a 2018 and I am running returnless. I have a supercharged LS3 in my car and ran it both returnless and with a return. It has a return now, but I run twin 450 lph pumps, so there is a lot of gas flowing at certain times.

[ShortHaul]

Originally Posted by Joyridin

I'm not sure why switching from a return style to returnless would make the engine run poorly. You are still delivering X amount of gas at X amount of pressure. The only time I would not run a returnless is if I had a highly modified or boosted engine. I have had both styles on my car and never noticed a difference. I have no clue why you would even have to tune it until you are done with everything.

Personally, I would go with A from a simplistic standpoint assuming your tanks are in good shape. Tanks Inc. has the pump you want and they are 100% genuine, but they are $107 each.

I am installing an L83 in my truck from a 2018 and I am running returnless. I have a supercharged LS3 in my car and ran it both returnless and with a return. It has a return now, but I run twin 450 lph pumps, so there is a lot of gas flowing at certain times.

What I read was that since the return style rails are vacuum referenced, meaning the pressure fluctuates based on the vacuum produced at different rpms (52 psi at idle, then ramps up to 58 as more throttle is applied) that the computer is tuned to account for this. I read that if you don't adjust the fuel mapping after you change to a returnless rail that it will not run as well as it could/should. Now in all honesty none of that really matters as I plan to have the motor tuned once I get it all put together.

That being said... If I go with Option A, how would you suggest I account for the return style fuel rail situation? Swap to a returnless rail (approx $115) or run a return line and install a bulkead fitting into my tank to return the fuel. (approx $50 in line, fittings etc.) One downside to swapping the fuel rail to returnless is if I do want to use a dual tank system I wont be able to use the Pollack tank switcher... as it has a return line too. I could still achieve dual tanks with a returnless system though... I saw one setup where the both tanks are plumbed to a Y block and the fuel tank selector switch just sends power to one tank's pump or the other. Actually seems a bit simpler than the Pollack valve. And cleaner because you can run 2 lines with AN fittings instead of 6 lines with hose clamps for the pollack.

I appreciate all of you for chiming in here, learning more with every step as I go.

[Joyridin]

Originally Posted by ShortHaul

What I read was that since the return style rails are vacuum referenced, meaning the pressure fluctuates based on the vacuum produced at different rpms (52 psi at idle, then ramps up to 58 as more throttle is applied) that the computer is tuned to account for this. I read that if you don't adjust the fuel mapping after you change to a returnless rail that it will not run as well as it could/should. Now in all honesty none of that really matters as I plan to have the motor tuned once I get it all put together.

That being said... If I go with Option A, how would you suggest I account for the return style fuel rail situation? Swap to a returnless rail (approx $115) or run a return line and install a bulkead fitting into my tank to return the fuel. (approx $50 in line, fittings etc.) One downside to swapping the fuel rail to returnless is if I do want to use a dual tank system I wont be able to use the Pollack tank switcher... as it has a return line too. I could still achieve dual tanks with a returnless system though... I saw one setup where the both tanks are plumbed to a Y block and the fuel tank selector switch just sends power to one tank's pump or the other. Actually seems a bit simpler than the Pollack valve. And cleaner because you can run 2 lines with AN fittings instead of 6 lines with hose clamps for the pollack.

I appreciate all of you for chiming in here, learning more with every step as I go.

Hmmm...well, I guess that might be an issue, but it isn't something I would worry about. I would just do away with the return altogether and put in the returnless fuel rail. Man..that seems like a lot of work running the return for a stock engine. My twin pumps go into a Y, then through the filter to the rail. I have a single return, but I am returning it to a single tank. The pumps are valved so the gas won't go backwards, so just putting in a Y makes it pretty easy.

[ShortHaul]

Originally Posted by Joyridin

Hmmm...well, I guess that might be an issue, but it isn't something I would worry about. I would just do away with the return altogether and put in the returnless fuel rail. Man..that seems like a lot of work running the return for a stock engine. My twin pumps go into a Y, then through the filter to the rail. I have a single return, but I am returning it to a single tank. The pumps are valved so the gas won't go backwards, so just putting in a Y makes it pretty easy.

The returnless rail swap seems like a pretty straightforward job. If i did that then I could run either the holley drop in module or the 87+ tank and factory pump with corvette reg...

[ShortHaul]

So I reached out to the Holley tech line to get their input, and the guy responded saying that he'd just cap off the return fuel rail and run their EFI module. I guess I'm just not convinced that's a better move than replacing the rail with a returnless... Anyone with actual firsthand knowledge chime in? In regards to tuning?

[Joyridin]

Originally Posted by ShortHaul

So I reached out to the Holley tech line to get their input, and the guy responded saying that he'd just cap off the return fuel rail and run their EFI module. I guess I'm just not convinced that's a better move than replacing the rail with a returnless... Anyone with actual firsthand knowledge chime in? In regards to tuning?

I don't see what it would matter. The aftermarket rail I have can be run in numerous configurations. Unless you were using an LSA rail, it really isn't going to matter.

[ShortHaul]

Annnnd i just got off the phone with Holley's tech support... This guy said definitely NOT to cap off the return, instead run a return line to a bulkhead fitting in the top of the sending unit. His reasoning was:
A. Cooler fuel. Fuel being cycled and returned into the tank helps keep it cool, and keeps the pump cool in turn. Cool=happy.
B. The factory fuel rail with vacuum pressure regulator is designed for a return system. Take that away and you end up deadheading fuel into the rail which can mess with the tuning.

Makes sense to me...

On another note, has anyone heard of running a transfer pump in the auxillary tank to feed fuel into the main tank? Instead of plumbing it into the actual fuel system, it just serves as a reservoir to transfer over to the main?

[87chevy.com]

My plan, still is when I get around to it is to wire the passenger tank as a spare tank with stock 87 sender in it to pump fuel into the driver tank through an -6an bulkhead fitting drilled into the top of the tank.
the dual tank switch only to switch level sensor readings so i can turn the pump off.
with the gen5 swap, I dont want to try running 72 psi through the chinese-ium fuel cross over valves out there

clint

[Joyridin]

Originally Posted by ShortHaul

Annnnd i just got off the phone with Holley's tech support... This guy said definitely NOT to cap off the return, instead run a return line to a bulkhead fitting in the top of the sending unit. His reasoning was:
A. Cooler fuel. Fuel being cycled and returned into the tank helps keep it cool, and keeps the pump cool in turn. Cool=happy.
B. The factory fuel rail with vacuum pressure regulator is designed for a return system. Take that away and you end up deadheading fuel into the rail which can mess with the tuning.

Makes sense to me...

On another note, has anyone heard of running a transfer pump in the auxillary tank to feed fuel into the main tank? Instead of plumbing it into the actual fuel system, it just serves as a reservoir to transfer over to the main?

It actually doesn't cool the fuel. It make it hotter. Touch the fuel rail on a nice warm day after you drove the car for a few miles and you will see why. All that heat from the engine and under the hood is being soaked up by the fuel and returned to the tank.

Start your truck and just let it run for 20 minutes without turning the steering wheel, then stick your finger in the P/S fluid. Pretty much the exact same concept. It will take longer with the gas due to the tank size and the fact the p/s fluid is at a lot higher pressure.

The factory returnless system is a deadhead system regardless of how you look at it. It doesn't matter if you regulate the pressure in the tank using the Holley module, or with the filter using the Corvette filter/regulator. It still ends up being a deadhead at the engine. Even using a carburetor is eventually a deadhead system. The benefit of having a return system at the fuel rail is more even fuel distribution when you are running a turbo/supercharged engine. Having a cylinder a bit lean when running 20 PSI of boost will kill the engine instantly. You don't have these issues with an almost stock engine running stock injectors.

Maybe you should call Holley a 3rd time? Take the average of all 3 techs?

[ShortHaul]

Originally Posted by 87chevy.com

My plan, still is when I get around to it is to wire the passenger tank as a spare tank with stock 87 sender in it to pump fuel into the driver tank through an -6an bulkhead fitting drilled into the top of the tank.
the dual tank switch only to switch level sensor readings so i can turn the pump off.
with the gen5 swap, I dont want to try running 72 psi through the chinese-ium fuel cross over valves out there

clint

I like that idea... can get a factory 87 sender with pump for pretty cheap. fill up the spare tank, when the main gets low, hit the switch and watch the fuel gauge rise. Although... just looked at the specs for a stock 87 pump and it lists 37GPH for the rate... It'd take a half hour to transfer a 20 gal tank! Maybe a walbro 255 (67 GPH) would be better... or perhaps a traditional low pressure pump... holley has a 95GPH for $75.

[1957 Chief]

The first squarebody LS I built, I ran the factory tanks with the ep381 pump, corvette regulator, and dead headed the fuel. That was in 2016, truck is still going strong today. This option is fairly straightforward and easy, and not a darn thing wrong with it. Also, you might want to research the switching valve if you plan to run both tanks, they make a diff one that can hold higher pressures...original one will not hold up.

Second truck I built, I chose the Boyds tank, and still ran a returnless fuel setup with the corvette regulator. Since then I have only used the Boyds tank with the corvette regulator on all my builds.

Bottom line, I never have plumbed a return line from the fuel rail. Yes hotter fuel is not as efficient as cooler fuel, but we aren't squeezing out the last bit of HP from these trucks just to "have a number." The quicker you can get past all the diff fuel system options (as you know there are a TON,) then you can attack the next problem.

If you just want to get the truck going on the most inexpensive side, get a 1987 tank, with the in tank pump (ep381), set it up for an LS with the corvette regulator, and get to driving your rig. Then later on add the secondary tank if you want.

My $.02

Bubba

[verdell]

Originally Posted by 1957 Chief

The first squarebody LS I built, I ran the factory tanks with the ep381 pump, corvette regulator, and dead headed the fuel. That was in 2016, truck is still going strong today. This option is fairly straightforward and easy, and not a darn thing wrong with it. Also, you might want to research the switching valve if you plan to run both tanks, they make a diff one that can hold higher pressures...original one will not hold up.

Second truck I built, I chose the Boyds tank, and still ran a returnless fuel setup with the corvette regulator. Since then I have only used the Boyds tank with the corvette regulator on all my builds.

Bottom line, I never have plumbed a return line from the fuel rail. Yes hotter fuel is not as efficient as cooler fuel, but we aren't squeezing out the last bit of HP from these trucks just to "have a number." The quicker you can get past all the diff fuel system options (as you know there are a TON,) then you can attack the next problem.

If you just want to get the truck going on the most inexpensive side, get a 1987 tank, with the in tank pump (ep381), set it up for an LS with the corvette regulator, and get to driving your rig. Then later on add the secondary tank if you want.

My $.02

Bubba

I agree 100%. We've done about the 7 of them the exact same way with stock '87 fuel tanks and it works.

[ShortHaul]

So... After reading tons of info and asking a million questions, I've decided my fuel system setup, for now... Thank you to everyone who has offered advice, opinion, tips and tricks. Much appreciated. I'll continue to post in here as parts arrive and are put in place.

Spectra GM1C tank (found one for $83 on the 'Zon)
Spectra FG05M Sender ($114 from Hot Rod Fuel Hose)
Spectra SP1115 190lph pump (Scored for $35.00 on Ebay)

It took a LOT of searching, but I was able to track down some decent prices on these items. The pump normally lists for $109 on Hot Rod Fuel Hose's website, and the Walbro 255, EP381 are sold out or over $100 everywhere I looked.

I'm going to get all these parts in and map out the rest of the fuel system... I think I'm going to avoid the Pollack switching valve altogether, and if I choose to add the aux tank in I'll use the transfer style external pump setup. That will allow me to run AN fittings right off my main tank to my existing return-style fuel rail.

[ShortHaul]

Finally got rolling on my fuel system. 1987+ Fuel sending unit PN: Spectra FG05M- Driver's side
Pump Spectra Sp1115 190lph

Ordered the sender from Hot Rod Fuel Hose and scored the pump off ebay. Assembly was rather simple, but the instructions were useless, so just look at the picture and piece it all together. One thing is the pump came with the higher quality clamps that require the special tool to install. I'm sure regular worm gear hose clamps would work fine... I just hate those things!

Untitled by awesome_adawson, on Flickr

Untitled by awesome_adawson, on Flickr

Untitled by awesome_adawson, on Flickr

I ordered a big bundle of fuel plumbing from Hot Rod Fuel Hose... They have a nice website with an in-depth guide to follow on how to plumb your fuel system. Nice to be able to find it all in once place and prices are good too!

https://hotrodfuelhose.com/blogs/rad...fi-conversions

[aggie91]

Option B all day long.

I see that you have decided to go that route. One thing that I have learned from my last swap, the factory tanks without the EFI baffle do work and I have not had any issues doing that. I will say, I rarely run below 1/8 of a tank...

[ShortHaul]

So... ran into a bit of a pickle here... 87+ fuel tanks have a 1 11/16th inch opening on the filler tube. The filler neck from 75 is 1 3/8". I can't seem to find a filler hose that has 1 3/8 on the filler side and 1 11/16 on the tank side. As popular as these swaps are, I'm surprised the fix for this isn't all over the web. Chime in with anything you've found...