I am planning on switching over to EFI and have a question about the return line. My tank has the EEC setup on it. First is this system for venting the tank or is only to do with emissions? I dont have any use for emissions control so should I just cap all these off or reatach them as the EFI kit calls for a vented tank? I attached a picture of the nipples I am referring to. I am not sure what each does so please chime in. Is there any way to use one of them as a return line? I do know the sender is shot at, and groundup sells one with a 1/4" return already on it. I was thinking this will work, but is the 1/4 return on it adequet for EFI? I attached a pic of this as well.

From what I have read, EFI must have a return especially with fuel pressures running much higher than carb system. Also, your tank pickup must be completely changed. I'm guessing you will be using an in-tank pump. Something like the setup at tanksinc.com.

Well from what I have found out from Fast (who I'm buying my kit from) they say the original pickup with the 1/4 return on it will work fine. So I think I am going that route for now. They said the return is almost no pressure so it's not that much of a concern. The feed line on the other hand will have high pressure, but they sell a kit that fits up to my sender. They also said the nipples for the emissions control will be the vent so I think I'm good. He said as long as the tank doesn't build pressure it will be fine.

I drilled a hole in the top of my sender & JB WELDED a 3/8 line in place. I made sure that the line extended past the fuel sock. Its been working fine for 10+ years.

I was thinking that, but the guy said the 1/4 would be afine. So I'm thinking why not just buy a new sender with the return on it since my sender is done. I'm getting my longblock next week and then I will order the kit. What did you do as far as the venting? did you use the EEC for this? I did a lot of research and have come to the conclusion FAST is the way to go, I just found the master kit for $1899 so thats what I'm going with. Comes with the fuel line kit which i have heard is PITA to get together, but is supposed to be OEM quality. You guys running a FAST kit? I looked at holley, but there newer kits have no info on what they are about and I like that fast has a LCD tuner for monitoring the system.

I've seen 1/4 returns cause problems with 255 lph pumps. Too much restriction.

. What did you do as far as the venting? did you use the EEC for this? .

If you were asking me :D , my tank has the corner vents & they are still connected to the stock charcoal cannister setup.

Yeah thanks for the answer. I'm ditching the canistor and just going to hook it back up to what I believe is a moisture seperator that's mounted on the body right in front of the tank. Are these nipples simply a vent system? I went ahead and purchased the FAST kit today and should be here tomorrow form Summit racing. I'm going to try the 1/4 line for now an if I have issues I will do what Rick suggested and drill it out for a 3/8 line. Can't wait to get this sytem in.

I capped my vents, added a sump to the tank for return.

So how is the tank vented? According to Fast it must be vented and a vented cap is not sufficient. I thought about the added sump, but the tank is 3/4 full of gas and I dont have a container for it. Not to mention I already got the sender.

I often wonder what some of these EFI vendors are smoking... IMHO you are getting some bad advice.

The requirements for a fuel system on EFI are VERY different than those for a carb system.

A) The high pressure fuel pumps needed for EFI are noted for being poor fuel suckers. This is one reason why most are mounted inside the fuel tank where they do not need to lift fuel any height. You may have issues getting the pump to prime if it must lift fuel up over the top of the tank.

B) The fuel supply must be constant if you want the engine to run constant. If you don't mind the engine cutting out sometimes, especially when the tank gets below about 1/2 full, then go ahead and run a stock fuel puckup. Otherwise you need some kind of reservoir or surge tank setup. Note that the A-body fuel tank is optimized for great fuel slosh ;)

C) When operating under idle conditions very little fuel is required by the engine. Read that as almost NO fuel is required. Which means that everything the pump puts out has to be returned to the tank. Not only does it need to be returned but you need it to flow well enough so that there is not any backpressure. Backpressure will play havoc with your fuel rail pressure and thus your fuel tuning. And you will probably already be running the injectors with minimal pulse timing... so you may not have any room to cut them further if fuel rail pressure is too high. I believe in avoiding problems in the first place rather than try and figure them out on the fly, so I recommend using the same size return as the feed line. You may well have enough other challenges/problems to figure out without adding any more.

If you have the EEC tank then by all means run the EEC venting setup. It is far better than what GM had designed previously. The charcoal cannister portion of the system may be optional but IMHO the venting and seperator setup is not. I retro-fitted one to my '68 El Camino with absolutely NO regrets :thumbsup:

You can also search out "MU-2021" to see what I did for an in-tank pump setup for EFI. This is a topic that we have discussed quite a bit already in this forum too.

I cannot vouch for the Holley systems, but I have seen a couple of FAST setups run into challenges getting everything setup and working properly. It is a very capable and flexible system which makes it a challenge to figure out how it all plugs together. Especially if the documentation is not straight forward.

Yeah I see what you are saying. What FAST told me about the return is its really not so much pressure as it is volume once it's on the return route. I can see why at Idle a lot of fuel would be returning. So I'm thinking I will go ahead and just change out the line on the pickup for now. I really don't know what is invloved with putting a sump in the original tank. If it comes down to it I will pull the tank and take it to a shop to have it done. It only took me about 20 min to pull it. I really appreciate the feedback. Seeing as how I have never went with fuel injecton I want to know as much as possible. I definately have read a lot of info on here on what others have done for this system. You know the funny thing is they said they have a test car that is similar to a Chevelle and said they are running the external pump with no issues.

my car runs fine with just a vented cap, no problems.

my car runs fine with just a vented cap, no problems.
Yep lots of things do work and the car runs fine. So let me see if I can explain the difference without coming across as being argumentative or critical ;)

It can be said that a carb runs just fine with no problems, yes? But we know that a car with EFI runs even better.

If you were to have some fuel slosh and leakage from the gas cap would that be a problem? Maybe, maybe not. But if you had a solution that prevented all potential leakage from the gas cap, would that be better?

It is a matter of degrees here between what works. Much like we choose to use the better solution when we upgrade from carb to EFI, I advocate using the better solution with respect to fuel tank and venting.

Another example, Yes you can use a regular pickup and external inline fuel pump with EFI and the car will run. Probably run just fine much, perhaps even most, of the time. But it will not run as well as it could utilizing an internal pump and some form of surge tank :yes: If designed well a sump comes pretty close too.

I was looking at the surge tank, how exactly does this work and what's a good brand to go with. Also, If I was to go with a sump do I just cap off the pickup and use the sump? Also would the vent line go to the sump as well? I see what your saying about the fuel system and I am sure "better is of course better". I know summit racing sells a sump kit to weld onto the tank for about $70, do you believe this is a good route to go? I definately don't want to spend 2k on a EFI kit and it not perform right.

YMMV but personally I am not a fan of sumps. They hang down into potential harm's way and it is not easy to design a sump for the variation of forces (cornering/acceleration/deceleration).

I like to start with a definition of the problem and then see how potential solutions solve the problem (yeah I am an engineer). In the EFI case the problem is to prevent air from reaching the fuel system intake.

With a sump you still have slosh and very little fuel left in the sump under some conditions. This can be mitigated some using baffles but the sump needs to be able to refill, so baffles are more of a damper. They do not prevent slosh flows, just slow them down. Thus I do not favor baffled tanks so much either.

Note that another weakness of the baffled tank solution is that as the fuel level in the tank drops so too does the fuel level inside the baffles. This reduces the margin of error before air reaches the fuel intake.

With a surge tank you can shape and orient the tank to control slosh using smaller but taller shapes. You also use two fuel pumps: one high pressure that feeds from the bottom of the surge tank, and another low pressure that feeds from the main tank into the surge tank. This is the weakness of the external surge tank, that it requires two fuel pumps. But it is very effective and used extensively in some parts of the world (like Austrailia). The EFI return is routed into the surge tank and a secondary surge tank overflow return is routed back to the main tank. The low pressure surge tank feeder pump needs to be of a type that self-primes and otherwise tolerates fuel interruptions. When the fuel feed from the main tank pulls air the surge tank fuel level will drop until the main feed again provides fuel. Thus the main tank feed must provide a higher volume than the engine consumes so that it refills the surge tank.

As to returns they usually return back near to the feed point. In this manner the refill rate is reduced to merely what the engine actually consumes. Returning elsewhere increases the required refill rate to the full pumping rate.

Vent lines always run to high points to avoid venting fuel.

Note that the fuel pump modules commonly used by the OEMs are a rather special form of surge tank placed inside the fuel tank. They run off one electical pump and use excess high pressure fuel to feed a venturi jet pump as the second surge tank feeder pump. As such they can maintain a fuel level higher than the fuel tank itself. Very cool solution :thumbsup:

I was reading about the OEM solutions and it seems they would be a nice fix for an older model vehicle wanting to upgrade to EFI. It just seems like there would be a way to replace the sender with another bolt in sender ready to go for EFI. I am a bit on the fence on what I should do. While the surge tank seems like a nice solution, I am unsure where to get one nor the details of putting it together and where to put in on the car. I would imagine it should be close to the tank since according to the EFI instructions it should be close to the fuel tank. I was thinking of getting a EFI tank, but from what I have read the cheaper (SPECTRA) tanks they are not a good solution as people have fuel starvation issues during cornering. It's funny how the hardest part of this transition to EFI is figuring out the best option for fuel delivery.

Would a fuel cell solve some of these problems? Although I prefere the tank mounted out of the trunk, I would go this route if it meant a better fuel system.

Yep lots of things do work and the car runs fine. So let me see if I can explain the difference without coming across as being argumentative or critical ;)

It can be said that a carb runs just fine with no problems, yes? But we know that a car with EFI runs even better.

If you were to have some fuel slosh and leakage from the gas cap would that be a problem? Maybe, maybe not. But if you had a solution that prevented all potential leakage from the gas cap, would that be better?

It is a matter of degrees here between what works. Much like we choose to use the better solution when we upgrade from carb to EFI, I advocate using the better solution with respect to fuel tank and venting.

Another example, Yes you can use a regular pickup and external inline fuel pump with EFI and the car will run. Probably run just fine much, perhaps even most, of the time. But it will not run as well as it could utilizing an internal pump and some form of surge tank :yes: If designed well a sump comes pretty close too.

Can you translate it into the basics pelase? I have a OEM tank (Spectra) with an added sump at the bottom and a return line into the filler neck. I use a Walbro inline pump mounted about a foot from the tank. I capped off the ports at the top of the tank when I put it in. Is there a better way using more or less the same parts I have?

Can you translate it into the basics pelase? I have a OEM tank (Spectra) with an added sump at the bottom and a return line into the filler neck. I use a Walbro inline pump mounted about a foot from the tank. I capped off the ports at the top of the tank when I put it in. Is there a better way using more or less the same parts I have?
First if you are happy with how your setup works then don't change it all. Cannot get more basic than that :D

Reading now I think we may have gotten thoughts crossed up in communicating them. You wrote "capped off the ports at the top" which I read as the vent ports. Now I think you really meant the sender ports. I like running the OEM venting as used on the EEC system along with a sealed gas cap. A lot of guys plug off those vents because they do not understand how they work and associate them with evil emission controls.

I think I might try and move your return from the filler pipe to the sump. You could do that using either a fitting on the sump or a tube from the original sender setup.

Further steps would only be warranted if you have problems and an external surge tank would be the path to reuse the most of your current parts. Lots of examples on the net if you search them out.

First if you are happy with how your setup works then don't change it all. Cannot get more basic than that :D

Reading now I think we may have gotten thoughts crossed up in communicating them. You wrote "capped off the ports at the top" which I read as the vent ports. Now I think you really meant the sender ports. I like running the OEM venting as used on the EEC system along with a sealed gas cap. A lot of guys plug off those vents because they do not understand how they work and associate them with evil emission controls.

I think I might try and move your return from the filler pipe to the sump. You could do that using either a fitting on the sump or a tube from the original sender setup.

Further steps would only be warranted if you have problems and an external surge tank would be the path to reuse the most of your current parts. Lots of examples on the net if you search them out.


I had always heard not to return to the sump as it can casue cavatation.... is that not true?

I have looked at surge tanks and it seems like a decent solution. I just wish someone had an example of what they did and where they purchased the parts for this. I also notice people have said they used two pumps with this setup.

Kirk, I have a surge tank & use 2 pumps. Been that way for at least 10 years. I searched the internet for "surge tank" and found many many pages showing how to build one. But not being a welder I bought one - from Australia. At that time I could not find one any place else.

I use a low pressure fuel pump, right out of the tank to fill the surge tank. The hi pressure pump is fed from the surge tank. I burnt out 2 Hi pressure pumps in 2 years before I added the second pump & surge tank. Electric pumps do not suck (out of the tank) very well but are excellent pushers. Apparently the low pressure pump is not as sensitive as the Hi pressure pump.

My hose routing is; from the tank thru the low pressure pump. Into the second lowest fitting on the surge tank. Then out the lowest fitting on the surge tank to the Hi pressure pump. Then to the fuel rail. The fuel return line goes back to the second highest fitting on the tank. And finally from the highest fitting back into my fuel tank.

The low pressure pump is above the front of the gas tank, the surge tank is mounted just ahead of the axle and the Hi pressure pump is on the frame under the passenger seat. My Elky is up on jack stands so pictures will be easy to take.....but I'm gonna be real busy the next few days. If I don't send you an email with pics by Monday, please PM or Email ( rickas at chevelles dot com) .

I had always heard not to return to the sump as it can casue cavatation.... is that not true?
Well... for cavitation you need a mix of air and if your fuel system is designed correctly there should be none of that in the return line. Looking at it another way every single OEM setup I have ever seen runs the return back into the sump or surge tank.

Now there might be some adverse affect if you shoot high velocity fuel right at the pickup. But use a large enough return line with a bit of offset and you should not have any problem.

I have looked at surge tanks and it seems like a decent solution. I just wish someone had an example of what they did and where they purchased the parts for this. I also notice people have said they used two pumps with this setup.
I have seen plastic water filter housings used as surge tanks... the cool think about this is you can embed the high pressure EFI pump inside the surge tank. The downside is they are a bit long and tough to fit.

I have also seen cannister fuel filters used as surge tanks. A number of 4x4 EFI conversions have gone this direction.

Rick described the connections pretty well :thumbsup:

Most of the hits you get on an Ebay search for "surge tank" will be stuff down under.

Rick, what do you think bout this tank?
http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=1037194381&adtype=1&size=1x1&type=3&campid=5336121898&toolid=10001 http://cgi.ebay.com/ebaymotors/Aluminum-Fuel-Surge-Tank-2-Litre-Swirl-Pot-System-_W0QQcmdZViewItemQQhashZitem2a0849a446QQitemZ18052 7670342QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries (http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5336121898&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2Febaymotors%2FAlum inum-Fuel-Surge-Tank-2-Litre-Swirl-Pot-System-_W0QQcmdZViewItemQQhashZitem2a0849a446QQitemZ18052 7670342QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries)
Looks pretty good and is a shape I might be able to mount in a lot of different locations. I notice many of the tanks are round and this seems like they would be hard to mount. I assume the extra holes are just for routing optons of the lines and could be plugged. I'm thinking the two pumps and this tank would make things much easier. I was also wondering how you wired two pumps, is there an issue with electrical draw and are they loud? I've seen some complaints about noise. What type of low pressure pump do you suggest?

That looks like a nice tank. I don't think in metric and the 2 liter size seems like it might be too big to fit comfortably. My quick (mis)calculation shows it to be approx 7x5x5 - if so its not too big at all.

I originally used one of the small cube pumps available at Walmart and it was VERY noisy. I bought a pump for a mid 80's throttle body buick on ebay and it is virtually silent and was cheap! For power I ran a jumper from the power side of my hi pressure pump thru a fuse to the low pressure pump. Its been years, but I "think" that the hi pressure pump was protected by a 15 Amp fuse, so total draw was less than 15 Amps.

You might want to check and see what thread is used on those output ports. If it is metric you may have trouble with fittings.


This is similar to the low pressure pump that I am using: http://cgi.ebay.com/ebaymotors/ACDelco-EP12S-Fuel-Pump-AC-Delco-Electric-External-GM-/370408460256?cmd=ViewItem&pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3ABuick&hash=item563e108fe0

Anybody have a diagram handy or picture of a surge tank setup?

I didn't think about the threads being metric. I'll have to message and ask. The measurements convert to 6.3x5.1x5.1 inches. It does sound a little large, but I was thinking the square size would be easy to mount and i might be able to find a spot for it. There are other square tanks on there where they post the fitting size. I was reading about the round takes need to be mounted vertically, which would mean I would have to mount in the engine bay. I really would prefere to mount it under the car and out of site, and the fact that routing line and the pumps all in the same area would be less of a pain. Rick, do you think you can post those pics here on the forum of your setup?

Here's another one with 6an fittings which should work fine. Its a bit shorter as well.

http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=2119943418&adtype=1&size=1x1&type=3&campid=5336121898&toolid=10001 http://cgi.ebay.com/ebaymotors/Fuel-Surge-Tank-Aluminum-2-Litre-Swirl-Pot-System-/300403171249?cmd=ViewItem&pt=Motors_Car_Truck_Parts_Accessories&hash=item45f16c9fb1 (http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5336121898&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2Febaymotors%2FFuel-Surge-Tank-Aluminum-2-Litre-Swirl-Pot-System-%2F300403171249%3Fcmd%3DViewItem%26pt%3DMotors_Car _Truck_Parts_Accessories%26hash%3Ditem45f16c9fb1)

Anybody have a diagram handy or picture of a surge tank setup?

Google is your friend: http://carmutations.com/tiki-index.php?page=EFI%20Surge%20Tanks There are many many variations on what can be used. In a few minutes I found homemade surge tanks made from a diesel fuel filter, water filter (house style) , rad overflow tank & an A/C drier. I couldn't/wouldn't vouch for the safety of some of them.

"Rick, do you think you can post those pics here on the forum of your setup?"

I will when I have opportunity. My 88 year old father in law got 2 stents put in his heart today and will probably be in hospital thru sunday. Once he is back home, I will have more time.

Thanks Rick.

The thought of running 2 fuel pumps sorta sucks...the chances of one failing just seems almost certain. Be nice to use a mechanical pump to feed the surge tank mounted up front, but there's the saftey issue again. 2 electric pumps would create enough draw that a possible alt. upgrade may be needed, especially in my case.

Sorry to hear that, just take your time. Thanks for the links, I had less luck finding anything using Yahoo search.

Anyone know what the bracket being used for the fuel filter is on this page?http://carmutations.com/tiki-index.php?page=EFI%20Surge%20Tanks
I'm thinking they used a oil filter bracket similar to this one.
http://www.summitracing.com/parts/PRM-1791/?rtype=10
The thing is theres no picture of the underside from summit and I'm wondering if the brass tube pickup was added by the person on the website. They didn't include any info on the bracket, so anyone have any ideas?

Regarding the surge tank guys...

Would the tank have to be rather "tall" or cylindrical to keep the bubbles away from the high pressure pump fittings? In other words, I could see the low pressure pump catching a whiff of air once in a while, and then pushing bubbles into the surge tank. If the surge tank was small or shallow, its possible that the high pressure connection/hole could grab some of these bubbles. Seems to me a taller tank would minimize this, where a shallow one would just let them pass right through.

Pictures of my low pressure pump and surge tank. I think that the descriptions pretty much describe what is going on. Remember that this is for a basically stock TPI system in an el camino. The floor pan in a chevelle is probably significantly different. http://www.chevelles.com/showroom/showphoto.php/photo/20590/cat/500/ppuser/1865

and http://www.chevelles.com/showroom/showphoto.php/photo/20591/cat/500/ppuser/1865

Hope this helps to picture what needs to be done.

Thanks Rick, makes complete sense.

Thats pretty much how I was thinking too. I guess the trunk would be a second choice if I have clearance issues. I think that square one on ebay is the way I will go. I know I have some room in front of the tank like yours. Im definately going this route now. Seems like a good fix and much cheaper than a new tank.

I basically have scratched the idea of putting the tank under the car. There is just no room. I'm thinking of using a canister filter on the firewall. Seems to be the only choice right now because of space issues.

I was thinking up by the battery, just a nice cylindrical can. Actually, think I'm gonna try sumping the tank, but cutting a hole or two in the tank to feed the sump, rather than cut a hole the size of the sump itself. If I dont get the results I'm looking for, I'll look into the surge tank. Just dont like the idea of running 2 pumps at this point.

I hear you on the pumps but I hear bad things about the sump. I think I will use my mechanical pump for the low pressure side. Im looking into placement options for the tank. By the battery or on the firewall might be a good spot.

My concern regarding the surge tank as I mentioned previously, is that the low-pressure pump could catch a whiff of air, and send bubbles into the surge tank. Hopefully, the surge tank is deep enough so that the bubbles arent pushed down deep enough for the high pressure pump to grab hold of 'em. I'm just imagining here, no experience at all with this in real life, but I'm learing real fast. I would think that a sump in the gas tank would minimize (not cure) the amount of pickup uncovering that happens with a stock style pick-up. So in my mind, a good solution would be BOTH a sump and surge tank.

Keep us posted Kirk on your results.

I just bought a canister filter. It has the 4 input/outputs on it. I'm thinking this should work for now, I just don't want to put this in the trunk and cut holes for the lines. I was thinking the air probably won't be an issue as long as the fuel is being drawn from the lower part of the filter. I think this will cause any air from the mechanical pump to travel back to the fuel tank being the least path of resistance as it is vented. Of course I could be wrong, but hopefully this does the job. I know I am not going to spend $1100 for a tank some people say doesn't work as well as it should. This filter should hold a decent amount of fuel and I think as long as I'm not doing to much crazy driving it wont empty on me around a corner. I dont know how anyone else has done this without mounting either in the trunk or engine bay without having a custom tank built. There is just no space under the car. Even right in front of the tank between the axle it's tight. I suppose on the elky there is a bit more room in there especially after looking at those pics. There's inches on my chevelle.

I was thinking up by the battery, just a nice cylindrical can. Actually, think I'm gonna try sumping the tank, but cutting a hole or two in the tank to feed the sump, rather than cut a hole the size of the sump itself. If I dont get the results I'm looking for, I'll look into the surge tank. Just dont like the idea of running 2 pumps at this point.

If you add a sump to the tank, you definately don't want to cut the whole space out, it weakens that area of the tank. A couple large holes to let the fuel easily drop down is best. That also in fact helps keep fuel from running up if it were to ever get that low and you were braking or turning sharply (wouldn't last too long anyway with that little fuel left.)

If you add a sump to the tank, you definately don't want to cut the whole space out, it weakens that area of the tank. A couple large holes to let the fuel easily drop down is best. That also in fact helps keep fuel from running up if it were to ever get that low and you were braking or turning sharply (wouldn't last too long anyway with that little fuel left.)


I agree!

I'm gonna go against the grain here and mount sump towards the front of the tank. Figure that by me leaving the majority of the tank in place except for those couple holes, a "pocket" will be created in this sump. Should do a fine job trapping fuel in there. Only really has to hold fuel in there for a momentary hard launch or hard braking, then the fuel will level out...hopefully.

Yeah the sump will be my next step if the filter doesnt work. I figured I could use the filter anyways if it's not keeping up. I just dont like the sump hanging down thats why I'm trying the filter first and I don't have to buy a new tank since what I have read you cant weld on a used tank.