T' EFI return line into pump supply

CochinoFilipino · Feb 16, 2007

I'm thinking I can:
-Put a T connection between the fuel tank and in-line pump.
-Route the return line to this T.

I'm thinking the fuel lines will have enough cooling effect to keep the fuel temps down.

And that this would minimize any starvation issues with the non-baffled tank. The amount of fuel goint into pickup will be what's cosumed by the engine

Anyone see any problems with this?

66HertzClone · Feb 16, 2007

I think it might create some problems with the fuel pressure. Normally the return line has no "back pressure" other than the resistance of moving the fuel, you're now adding pressure to the return side. This might cause the pressure to rise despite the best efforts of the regulator to keep it at it's set pressure.

I am using the original tank, no baffles, an external pump, and have had no starvation issues. As a precaution I keep the tank above the 1/4 level.

CochinoFilipino · Feb 16, 2007

66HertzClone said:
I think it might create some problems with the fuel pressure. Normally the return line has no "back pressure" other than the resistance of moving the fuel, you're now adding pressure to the return side. This might cause the pressure to rise despite the best efforts of the regulator to keep it at it's set pressure.

I am using the original tank, no baffles, an external pump, and have had no starvation issues. As a precaution I keep the tank above the 1/4 level.

I'd be T'ing into between the Tank and the pump feed. i don't think there would be any back pressure there. The pump should be taking in as much as the return line feeds back into it.

Pressure after the pump, and before the regulator should be unaffected.

ForceFed70 · Feb 16, 2007

It's been done before, but not a good solution IMHO.

Especially for us guys with non-baffled fuel tanks. Having the return go back to the tank will allow the system to easily "burp" any air that may make it into the line (for example, during hard cornering with a low tank). Ting into the supply line will make it so that the air is recirculated back into the supply.

Have you seen my EFI writeup where I added a fitting to the fuel pump sender plate? If not, I'll give you a link to some info.

Another common solution is to tap the return into the rubber fuel filler hose. Or better yet, use the drain plug (my tank didn't have a drain plug).

CochinoFilipino · Feb 16, 2007

BottleFed70 said:
It's been done before, but not a good solution IMHO.

Especially for us guys with non-baffled fuel tanks. Having the return go back to the tank will allow the system to easily "burp" any air that may make it into the line (for example, during hard cornering with a low tank). Ting into the supply line will make it so that the air is recirculated back into the supply.

Have you seen my EFI writeup where I added a fitting to the fuel pump sender plate? If not, I'll give you a link to some info.

Another common solution is to tap the return into the rubber fuel filler hose. Or better yet, use the drain plug (my tank didn't have a drain plug).

Good point about getting air locked into the closed system. I was thinking that with so little fuel entering the pickup and at such a slow rate that short incident like a hard corner would not llikely lead to any air being sucked in.

And yes I did read parts of your very detailed and excellent write-up. But I'll admit that I didn't read ALL of it as it was quite lengthy and I'm a bit intimidated at with the idea of trying to tune an MS system.

ForceFed70 · Feb 16, 2007

CochinoFilipino said:
Good point about getting air locked into the closed system. I was thinking that with so little fuel entering the pickup and at such a slow rate that short incident like a hard corner would not llikely lead to any air being sucked in.

My pump actually moves alot of fuel. I can hear it spashing around in the tank from the return hose.

The non-baffled tanks can be a big problem for EFI swaps. On a carb, the air is burped out of the fuel bowl vents. On an EFI system the air can either be injected by the injectors (which causes a stumble or missfire) or sent back to the tank. Often what happens is a little of both.

bnickel · Feb 16, 2007

aeromotive supposedly has anew EFI specific tank for early stangs that has baffling, it's listed in the newest year on catalog but i can't find on aeromotive's website so i'm guessing it's really new.

bnickel · Feb 16, 2007

here is the listing on year one's site

O.E.-style fuel tank. Hardware and instructions not included.

Part # Description Price Add to Cart
AE18620 Fuel tank with sump and baffle for 1970 models.
$514.00

This product is discount exempt and is shipped oversize.

you can't link to it but it's under air/fuel > aeromotive > fuel tanks. they offer them for 69/70 but you should be able to retrofit either one to a 67/68 and possibly even 65-66 if needed.

CochinoFilipino · Feb 16, 2007

BottleFed70 said:
My pump actually moves alot of fuel. I can hear it spashing around in the tank from the return hose.

The non-baffled tanks can be a big problem for EFI swaps. On a carb, the air is burped out of the fuel bowl vents. On an EFI system the air can either be injected by the injectors (which causes a stumble or missfire) or sent back to the tank. Often what happens is a little of both.

I understand that the pump moves alot of fuel. But very little fuel needs to come from the tank since the return line would feed into the T near the fuel pump. Only the amount of fuel being consumed by the engine would enter the pick-up.

CochinoFilipino · Feb 16, 2007

bnickel said:
aeromotive supposedly has anew EFI specific tank for early stangs that has baffling, it's listed in the newest year on catalog but i can't find on aeromotive's website so i'm guessing it's really new.

Thanks. I just ordered the catalog.

I contacted the guy who will be making the underbed EFI tank for my truck. He said he'd do a mustang tank if I gave him some plans. Eventually I'll get around to this and get a quote from him.

Bullitt · Feb 18, 2007

you can also take a stock tank and cut a hole in the bottom and build a "sump" of sorts with thread in bungs. that's what I did for my '67 and it works great. Also fixed the issue of not being able to pull more than 10 gals out of the tank through the stock pickup.

68converted · Feb 18, 2007

I had been thinking something like this would work, but a few others have shot it down pretty heavily.

http://i48.photobucket.com/albums/f210/68converted/Fuelsystemidea.jpg

I am going to try it anyway. If it doesn't work then it's just a plumbing redo.

ForceFed70 · Feb 18, 2007

68converted said:
I had been thinking something like this would work, but a few others have shot it down pretty heavily.

http://i48.photobucket.com/albums/f210/68converted/Fuelsystemidea.jpg

I am going to try it anyway. If it doesn't work then it's just a plumbing redo.

If I understand that diagram correctly, you plan to run a line between the fuel pump low pressure side,and the return line but also run the return line back to the tank.

If so, I think it'll work but I don't understand why you would put in this extra line.

Generally you don't want to recirculate the fuel. After running through the system it gets hot and the mixture is well cavitated (full of little bubbles). Since you already have a return line to the tank, why not let the return fuel go where it can cool down and any bubbles will float to the top?

I'm interested to hear what the benifit of this design would be.

iskwezm · Feb 18, 2007

heres what i did for about 150 bucks with a sump with 2 -8's,a baffle(we made)and 3 -8's on top for a vent,return and extra one.
View attachment 402786

GOvert · Feb 18, 2007

Inexspensive pratical solution

I stumbled across this on a Bronco II site.
Link to Accumulator/Filter
I wonder if this is a deisel fuel system part. Does anyone know ?

68converted · Feb 18, 2007

I saw that accumulator unit before. I have been looking into a farm supply store that has various in line fuel filters that are in the 2 qt to 1/2gal size. I think I will now take the "T" on the return side to the tank and the filter, instead of tank and and pump feed line.

One I saw in a catalog had two feed fittings and one exit. I think it would work perfect, as a filter and accumulator all in one.

I will call them on Tuesday and post the info I get.

CochinoFilipino · Feb 19, 2007

68converted said:
I had been thinking something like this would work, but a few others have shot it down pretty heavily.

http://i48.photobucket.com/albums/f210/68converted/Fuelsystemidea.jpg

I am going to try it anyway. If it doesn't work then it's just a plumbing redo.

Hope you don't mind. I hi-jacked your pic and changed it to reflect what I wast thinking.

All the other solutions sound good. I was just looking for an easy way out. If I have to mod the tank, I'll likely just order a custom tank and use an in-tank pump.

ForceFed70 · Feb 19, 2007

CochinoFilipino said:
All the other solutions sound good. I was just looking for an easy way out. If I have to mod the tank, I'll likely just order a custom tank and use an in-tank pump.

Why not do this? Cheaper and easier than a new tank, not baffled tho..

Swede958 · Feb 19, 2007

I'll throw in my plans as well... on my car I had planned to move the gas cap ala the dodge charger to the upper left fender. Flush mount aircraft style filler recessed into the panel...

Anyways.. I did some looking around and found a tank out of a early 90s ford van that was just about the right size as our tank, and was for EFI. I have not seen the inside but I would assume that since it was EFI it would be baffled at least to some extent.

Here is the van tank... it would not take much to plump in a stock type fill tube to the opposite of the sending unit hole. I am building a floor to my trunk so the lines will be running under that and down through the floor toward the engine- again I planned to use a side mount fill.

Here is the stock tank for size comparisons.... oh the boredom days of working at an autoparts store- the stuff you find in nifty catalogs.

CochinoFilipino · Feb 20, 2007

BottleFed70 said:
Why not do this? Cheaper and easier than a new tank, not baffled tho..

My '67 C10 runs TPI with the stock non-baffled tank. And I don't like the occasional starvation it suffers getting on the freeway clover leaf.

Besides being easy, the main reason I was thinking of T'ing into the supply line was to feed the pump and hopefully avoid any starvation issues.

T' EFI return line into pump supply

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