EFI fuel lines & fuel sump

Belgian1979vette

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I need to put together a new order of parts, so I came up with some new questions on efi fuel lines and the sump.

About the sump : I know it would be better to have a sump welded to the tank, but since the 79 uses a bladder inside the tank, this is a mayor no. I came up with the idea to mount a fuel sump under the hood. This is basically comparable to a dry sump tank. I have one question though : the sump is fed by a low pressure pump. Will this stop pumping once the sump is full ?

About the fuel lines. I read a lot about seeping braided fuel lines, which is why I decided to move away from braided and go to alu tubing, only to use braided in those place that move vs eachother. I would like to retain the an fitting for ease of use and maintenance. Is there a reference chart which type/dimensions of sleeves to use with which tube diameter ? The tubes seems to be quoted in inch rather than AN sizes.
 
I thought 77 was the last year of the bladder. Why not just mount a 82 sending unit in your tank and mount a TPI fuel pump and not deal with all the sump hassles?
 
I thought 77 was the last year of the bladder. Why not just mount a 82 sending unit in your tank and mount a TPI fuel pump and not deal with all the sump hassles?

The 79 has a green lining as well. As far as the mounting of the pump in the tank : this doesn't help a thing, since it can become uncovered as well.

Do not know how the 82 tank was, but I think it has baffles.
 
I thought 77 was the last year of the bladder. Why not just mount a 82 sending unit in your tank and mount a TPI fuel pump and not deal with all the sump hassles?

The 79 has a green lining as well. As far as the mounting of the pump in the tank : this doesn't help a thing, since it can become uncovered as well.

Do not know how the 82 tank was, but I think it has baffles.

82 tank is plastic with a metal shell & no baffles

DSCF1012.jpg

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DSCF1022.jpg

inside tank

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what you are looking for is called a surge tank, it's basically a vessel with float bowls on the inlet. You can get them from anyone who deals in mech fi stuff like crower, kinsler or rons. They are expensive though

As for the AN sizes, the an sizes are fractions of inches and it's purposely done to relate to the OUTSIDE diameter of the hard line. So a 3/16 hard line corresponds to a 3an setup. Check this:

http://www.vettemod.com/forum/showthread.php?t=256&highlight=flare
 
Being I have a '72 with bottom tank drain that actually went up and over inside the pickup to allow mounting of the sending unit float, I just ran the FI pump mounted to the frame rail on the rear of the car, been there ever since, using high pressure hose to the stock 3/8 steel feeder line, and the stock 1/4? return line to the top of the tank....never has been a flow issue, I can crank that fuel pressure down to WAY lo, and jack it up to 65 lbs it runs at stock ~40 psi....

NOW that has nothing to do with a sump, for years I ran the car with an effective tank crapassity of an effective 14 gallons, because in a quick corner the fuel would slosh over to the left side and engine would stumble, sometimes even die.....usually around the 1/4 mark on the gauge....

some time ago, since removing the spare tire/carrier, I had extra room under there, bought a steel 5 gallon air tank, made of much heavier steel than the stock OEM tank, set it up under the main tank as a sump, it's lower than the main tank with a simple gravity drain, both the supply and return lines are plumbed into the sump tank, pickup at bottom of tank, return to top of tank, a very simple setup, really....cured the slosh problem, and gave me 5 gallons extra range...:smash: the pump has remained tied to the rear frame along with filter....:smash:
 
Being I have a '72 with bottom tank drain that actually went up and over inside the pickup to allow mounting of the sending unit float, I just ran the FI pump mounted to the frame rail on the rear of the car, been there ever since, using high pressure hose to the stock 3/8 steel feeder line, and the stock 1/4? return line to the top of the tank....never has been a flow issue, I can crank that fuel pressure down to WAY lo, and jack it up to 65 lbs it runs at stock ~40 psi....

NOW that has nothing to do with a sump, for years I ran the car with an effective tank crapassity of an effective 14 gallons, because in a quick corner the fuel would slosh over to the left side and engine would stumble, sometimes even die.....usually around the 1/4 mark on the gauge....

some time ago, since removing the spare tire/carrier, I had extra room under there, bought a steel 5 gallon air tank, made of much heavier steel than the stock OEM tank, set it up under the main tank as a sump, it's lower than the main tank with a simple gravity drain, both the supply and return lines are plumbed into the sump tank, pickup at bottom of tank, return to top of tank, a very simple setup, really....cured the slosh problem, and gave me 5 gallons extra range...:smash: the pump has remained tied to the rear frame along with filter....:smash:

My 82 has no baffles in the tank and it's CFI has never died or stumbled in hard cornering even with under 1/2 tank. Maybe yours does it because an intank pump has an immediate supply of fuel as soon as the sock has fuel near it again where as the frame pump has a lot of empty line between the pump and fuel supply so it draws a lot of air instead of fuel for a period of time and takes a few seconds to draw the fuel back to the pump.
 
Being I have a '72 with bottom tank drain that actually went up and over inside the pickup to allow mounting of the sending unit float, I just ran the FI pump mounted to the frame rail on the rear of the car, been there ever since, using high pressure hose to the stock 3/8 steel feeder line, and the stock 1/4? return line to the top of the tank....never has been a flow issue, I can crank that fuel pressure down to WAY lo, and jack it up to 65 lbs it runs at stock ~40 psi....

NOW that has nothing to do with a sump, for years I ran the car with an effective tank crapassity of an effective 14 gallons, because in a quick corner the fuel would slosh over to the left side and engine would stumble, sometimes even die.....usually around the 1/4 mark on the gauge....

some time ago, since removing the spare tire/carrier, I had extra room under there, bought a steel 5 gallon air tank, made of much heavier steel than the stock OEM tank, set it up under the main tank as a sump, it's lower than the main tank with a simple gravity drain, both the supply and return lines are plumbed into the sump tank, pickup at bottom of tank, return to top of tank, a very simple setup, really....cured the slosh problem, and gave me 5 gallons extra range...:smash: the pump has remained tied to the rear frame along with filter....:smash:

My 82 has no baffles in the tank and it's CFI has never died or stumbled in hard cornering even with under 1/2 tank. Maybe yours does it because an intank pump has an immediate supply of fuel as soon as the sock has fuel near it again where as the frame pump has a lot of empty line between the pump and fuel supply so it draws a lot of air instead of fuel for a period of time and takes a few seconds to draw the fuel back to the pump.

CFI runs on maybe 10 lbs pressure, and so the flow rate would have to be much less than the 40 lbs on a TPI, I suspect the lines are similar size...but the CFI has some sort of sump that it runs from..NO?

and you say 1/2 tank, I was saying 1/4 tank or less than that even...:surrender:
 
what you are looking for is called a surge tank, it's basically a vessel with float bowls on the inlet. You can get them from anyone who deals in mech fi stuff like crower, kinsler or rons. They are expensive though

As for the AN sizes, the an sizes are fractions of inches and it's purposely done to relate to the OUTSIDE diameter of the hard line. So a 3/16 hard line corresponds to a 3an setup. Check this:

http://www.vettemod.com/forum/showthread.php?t=256&highlight=flare

Thanks. I was looking for that link.
 
Using a teflon lined braided hose like Aeroquip TFE will eliminate the fuel smell and lining breakdown over time. I have them for most of my FI fuel lines and PS hoses as well. Not the cheapest, but reusable and will probably outlast the car.

Another option for a retrofit intank pump is to use a late model fuel pump bucket assembly (from Camaro, Corvette, etc). Vetteworks used to have a kit/template to adapt a 4th gen F body pump bucket to C3 tanks.

Phil
 
Being I have a '72 with bottom tank drain that actually went up and over inside the pickup to allow mounting of the sending unit float, I just ran the FI pump mounted to the frame rail on the rear of the car, been there ever since, using high pressure hose to the stock 3/8 steel feeder line, and the stock 1/4? return line to the top of the tank....never has been a flow issue, I can crank that fuel pressure down to WAY lo, and jack it up to 65 lbs it runs at stock ~40 psi....

NOW that has nothing to do with a sump, for years I ran the car with an effective tank crapassity of an effective 14 gallons, because in a quick corner the fuel would slosh over to the left side and engine would stumble, sometimes even die.....usually around the 1/4 mark on the gauge....

some time ago, since removing the spare tire/carrier, I had extra room under there, bought a steel 5 gallon air tank, made of much heavier steel than the stock OEM tank, set it up under the main tank as a sump, it's lower than the main tank with a simple gravity drain, both the supply and return lines are plumbed into the sump tank, pickup at bottom of tank, return to top of tank, a very simple setup, really....cured the slosh problem, and gave me 5 gallons extra range...:smash: the pump has remained tied to the rear frame along with filter....:smash:

My 82 has no baffles in the tank and it's CFI has never died or stumbled in hard cornering even with under 1/2 tank. Maybe yours does it because an intank pump has an immediate supply of fuel as soon as the sock has fuel near it again where as the frame pump has a lot of empty line between the pump and fuel supply so it draws a lot of air instead of fuel for a period of time and takes a few seconds to draw the fuel back to the pump.

CFI runs on maybe 10 lbs pressure, and so the flow rate would have to be much less than the 40 lbs on a TPI, I suspect the lines are similar size...but the CFI has some sort of sump that it runs from..NO?

and you say 1/2 tank, I was saying 1/4 tank or less than that even...:surrender:

even at that level I still never had problems.
 
Using a teflon lined braided hose like Aeroquip TFE will eliminate the fuel smell and lining breakdown over time. I have them for most of my FI fuel lines and PS hoses as well. Not the cheapest, but reusable and will probably outlast the car.

Another option for a retrofit intank pump is to use a late model fuel pump bucket assembly (from Camaro, Corvette, etc). Vetteworks used to have a kit/template to adapt a 4th gen F body pump bucket to C3 tanks.

Phil

Phil,

I know about the teflon, but this is rather expensive and not just the hose, the fittings as well + they do not always allow for the thight bends that I need around my intake manifold. Alu tubing doesn't allow this either but at least it is a whole lot less expensive.
 
Anyone experiencing any problems with alu fuel lines ? I was thinking going this route for the fact that these are easy to bend and flare.

I would not trust an aluminum fuel line running the length of the frame for nothing, not even close....too easy to snap from fatigue....

:smash::surrender:
 
Anyone experiencing any problems with alu fuel lines ? I was thinking going this route for the fact that these are easy to bend and flare.

I would not trust an aluminum fuel line running the length of the frame for nothing, not even close....too easy to snap from fatigue....

:smash::surrender:

It's not for the frame. I already have my stainless there. It's for the underhood routing.
 
Anyone experiencing any problems with alu fuel lines ? I was thinking going this route for the fact that these are easy to bend and flare.

I would not trust an aluminum fuel line running the length of the frame for nothing, not even close....too easy to snap from fatigue....

:smash::surrender:

It's not for the frame. I already have my stainless there. It's for the underhood routing.

Well, we have the FI system itself, plumbed in heavy tubing, and supported good at both ends, the LT1 and the L98 were not aluminum....I can't imagine putting any stress/vibration/engine torque on any solid line running from frame to engine....I used ~200 psi rubber FI hose, red markings for years, using Aeroquip steel reinforced hose now, double FI clamps at both ends on feed, return is not so paranoid...near zero pressure open to tank...:thumbs::twitch:
 
I used this kind of pressure line rated at 350 psi to replace my original plasitc fuel lines on my 97 camaro. Basically the hose guy just used my stock fuel rail connectors and hydraulic clamps. These run from the engine to down by the transmission.

DSCF1089.jpg
 
Coming back to this :

If using stainless hard lines, what do you use ? Annealed ? Seamless. I hear that tubes with a seam and non-annealed give problems when trying to flare them.
 
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