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Going EFI-Need advice on fuel hose selection


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Hello all,

 

I'm going the EFI route and one subject I have little knowledge in is fuel hose selection. I've had stainless braided I the past and I didn't like the fact that fuel smell would somehow seep through and that eventually you have to replace the hose earlier than other types.

 

I've been looking into push lock PTFE rubber hose as my choice. Anybody have any feedback on this type of hose or a better recommendation?

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Need to use good clamps too. System will produce 70psi fuel pressure and you don't want a line coming off. Something like this.

 

https://www.msdperformance.com/products/fuel_systems/atomic_efi/atomic_tbi/parts/2928

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Definitely PTFE lined hose. The Summit stuff is cheap and high quality PTFE. If you don't run PTFE you'll eventually have fuel permeation through the hose and an odor to match. I used AN fittings throughout my system.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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I replaced the original lines in my car with metal tubing for the long runs from the tank to the engine and back, using fuel injection hose for the connections to the tank and engine from the lines.

Installed pre and post fuel pump filters as well .

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I replaced the original lines in my car with metal tubing for the long runs from the tank to the engine and back, using fuel injection hose for the connections to the tank and engine from the lines.

Installed pre and post fuel pump filters as well .

 

That's what I was originally going to do to preserve the OEM look and it's metal tubing that I believe will last longer.

 

The instructions clearly state not to use stainless tubing? I don't know why though.

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I replaced the original lines in my car with metal tubing for the long runs from the tank to the engine and back, using fuel injection hose for the connections to the tank and engine from the lines.

Installed pre and post fuel pump filters as well .

 

That's what I was originally going to do to preserve the OEM look and it's metal tubing that I believe will last longer.

 

The instructions clearly state not to use stainless tubing? I don't know why though.

If you use hard lines and don't use a return system with a regulator you will see a hammering effect on hard lines when the pumps cycles. My system recommended the soft efi lines. Most pumps operate in PWM mode (Pulse Width Modulated) to reduce the loud pump noise with these systems. The PWM mode cycles the pump on/off to maintain fuel pressure so these surges affect the system operation with hard lines while the soft lines absorbs some of the surges.

 

You can use the vapor return lines in our cars for the fuel return from a regulator and then the use of the hard line would be acceptable. In my case I used soft lines from the tank, a fuel regulator and the the vapor return line with no issues so far.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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I'm not sure I would use the fuel vapor line as the return, tempting as it may be. I don't think it's got the diameter you ideally want for a return system.

 

I replaced the original lines in my car with metal tubing for the long runs from the tank to the engine and back, using fuel injection hose for the connections to the tank and engine from the lines.

Installed pre and post fuel pump filters as well .

 

That's what I was originally going to do to preserve the OEM look and it's metal tubing that I believe will last longer.

 

The instructions clearly state not to use stainless tubing? I don't know why though.

If you use hard lines and don't use a return system with a regulator you will see a hammering effect on hard lines when the pumps cycles. My system recommended the soft efi lines. Most pumps operate in PWM mode (Pulse Width Modulated) to reduce the loud pump noise with these systems. The PWM mode cycles the pump on/off to maintain fuel pressure so these surges affect the system operation with hard lines while the soft lines absorbs some of the surges.

 

You can use the vapor return lines in our cars for the fuel return from a regulator and then the use of the hard line would be acceptable. In my case I used soft lines from the tank, a fuel regulator and the the vapor return line with no issues so far.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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Isn't the vapor return 3/8ths? Is that sufficient for 425hp?

 

My vapor return is definitely not 3/8 tubing. My car is a '71 however, so perhaps the later years with additional emissions equipment had larger lines?

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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Isn't the vapor return 3/8ths? Is that sufficient for 425hp?

 

I actually used a drill and enlarged the opening in the cap to create more volume. No issues so far with the return. My motor should be putting out at least 425 HP. The supply line is 3/8th inch if I remember correctly.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Yeah, my primary feed line is -6AN along with the return. The vapor line looks like it's -4 or smaller. I'm running my vapor line to a late model Crown Vic canister controlled by the EEC-V purge solenoid.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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If you haven't already purchased the system maybe check out FiTech's enclosed sump pump system. Removes the need to run a recirc line back. It is pricey though.

1971 Mustang Grande, 351 Cleveland 2v, C6, 9"

-Fitech EFI

-Comp Cams 284hr

-Aussie Heads

-Weiand Xcelerator intake

-Long Tube Headers

-Boss Hogg "Street Bandit"

 

 

My Build

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Isn't the vapor return 3/8ths? Is that sufficient for 425hp?

 

I actually used a drill and enlarged the opening in the cap to create more volume. No issues so far with the return. My motor should be putting out at least 425 HP. The supply line is 3/8th inch if I remember correctly.

 

John,

 

I am contemplating upgrading to an in tank pump and using the existing vapor line as a return. Is there a check valve at the tank on the vapor line? I believe my vapor line is 5/16".

 

Apologies to OP if this is a hijack in progress.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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I replaced the original lines in my car with metal tubing for the long runs from the tank to the engine and back, using fuel injection hose for the connections to the tank and engine from the lines.

Installed pre and post fuel pump filters as well .

 

That's what I was originally going to do to preserve the OEM look and it's metal tubing that I believe will last longer.

 

The instructions clearly state not to use stainless tubing? I don't know why though.

 

I like the metal lined in case anything hits them they are tougher than rubber. Not sure on the stainless, but it's tough to bend.


Isn't the vapor return 3/8ths? Is that sufficient for 425hp?

 

I actually used a drill and enlarged the opening in the cap to create more volume. No issues so far with the return. My motor should be putting out at least 425 HP. The supply line is 3/8th inch if I remember correctly.

 

John,

 

I am contemplating upgrading to an in tank pump and using the existing vapor line as a return. Is there a check valve at the tank on the vapor line? I believe my vapor line is 5/16".

 

Apologies to OP if this is a hijack in progress.

 

Mine had no check valve but that vent line did have a very small orfice in the vent piece on top of the tank.

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Isn't the vapor return 3/8ths? Is that sufficient for 425hp?

 

I actually used a drill and enlarged the opening in the cap to create more volume. No issues so far with the return. My motor should be putting out at least 425 HP. The supply line is 3/8th inch if I remember correctly.

 

John,

 

I am contemplating upgrading to an in tank pump and using the existing vapor line as a return. Is there a check valve at the tank on the vapor line? I believe my vapor line is 5/16".

 

Apologies to OP if this is a hijack in progress.

 

There are no check valves. There is a screen and what I believe was a foam filter behind the screen that was pretty much gone. I removed the screen and foam and then used a drill that was slightly larger than the existing hole and opened up the hole a little. I made sure that there was sufficient metal left so that I could clamp the hose on without crushing the tube. My system maintains consistent pressure at idle and while running so the return line has sufficient volume capacity for my application.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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If you haven't already purchased the system maybe check out FiTech's enclosed sump pump system. Removes the need to run a recirc line back. It is pricey though.

 

They have turned out to be faulty. I never considered it because it's just adding another component and another connection that can fail.

 

You can read this link, the final pages are an interesting read.

 

http://www.corvetteforum.com/forums/c3-tech-performance/3670852-fitech-go-efi-review-12.html

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If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

 

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

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If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

 

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

 

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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I like the looks of the FiTech fuel command center, with the pressure gauge, plus a lot lower cost than the Edelbrock surge pump.

 

However, I can see a potential problem with teeing into the existing vent line. If not done correctly the vent for the fuel tank can be compromised, which would result in the fuel tank trying to vent through the FCC, creating a vacuum in the fuel tank and the FCC. I have to wonder if this is what's happening to the guys on the Corvette forum. Personally I would (will) consider a separate vent line to the fuel tank for the FCC. That way if the float/needle valve in the FCC gets stuck the fuel will just return to the tank.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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  • 4 months later...

If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

 

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

 

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

John, I am curious about the vent hole in the cap. Where in the cap did your drill? I am considering my options for fuel pump so the ability to use the charcoal line as return is appealing. I am considering the BobbMc PowerSurge pump, so the vent line won't be a "full" return line, just excess gas, I guess.

 

Also, you said you drilled the vent orifice on top of the tank. Without drilling, would the cap allow gas to flow back into the tank, or is it a one way system?

 

Another possibility is to add a second tube to the sending unit to use as a return line, but that implies running a whole new hose from the engine bay all the way back to the tank.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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If you do use the vapor as a return, the tank will still need a way to vent pressure changes in the tank and allow air in to replace the fuel used

 

I installed another dedicated return fitting in my set up, and ran soft lines to just past the pump and at the return fitting, as well as the vent line for about a foot or so.

Engine has soft fuel lines as well. In between is metal pipe.

 

To prevent a vacuum from occurring in the gas tank because it's a closed system now I made a small vent hole in my gas cap. This seems to have worked in my system.

John, I am curious about the vent hole in the cap. Where in the cap did your drill? I am considering my options for fuel pump so the ability to use the charcoal line as return is appealing. I am considering the BobbMc PowerSurge pump, so the vent line won't be a "full" return line, just excess gas, I guess.

 

Also, you said you drilled the vent orifice on top of the tank. Without drilling, would the cap allow gas to flow back into the tank, or is it a one way system?

 

Another possibility is to add a second tube to the sending unit to use as a return line, but that implies running a whole new hose from the engine bay all the way back to the tank.

 

I drilled a small hole in the cap to allow air to enter the tank so there would not be a vacuum created as the fuel is drawn out of the tank and I used the smallest drill bit that I had. On my car the top of the tank has a cap to return fuel vapor from the air cleaner to the charcoal can and back to the tank, This line is already plumbed so it made a perfect fuel return line for me. I did not have to modify the tank in any way to get this done and it seemed a logical choice for me. I now have 1500 miles on this system with no issues so it seems to be working. MY EFI system is for cars up to 500hp.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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