Fuel Line help

arvin429
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Fuel Line help

Postby arvin429 » Sat May 20, 2017 10:34 pm

I have my sr5 fuel tank and I was going to use it in the mean time while I save up a little more money to buy a GTS tank. I have the GTS pump assembly and I was wondering, do I really have to upgrade the fuel line diameter? There are conflicting posts of yes and no. If I had to upgrade it I would use 6AN stainless steel braided hose. How much feet would I need? Also for the charcoal canister would I be able to use my SR5 canister? What is the thread size on the Charcoal canister?
Thank You
Arvin

SgtRauksauff
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Re: Fuel Line help

Postby SgtRauksauff » Mon May 22, 2017 11:58 am

I don't remember the charcoal cannister (part of the EVAP system) even having threads, just hoses and clamps. there is no pressurized fuel, only fuel vapor in the evap line, at least there shouldn't be. Basically, as the fuel sloshes around and gets agitated in the tank, and the return line puts some back in, sometimes there can be a bit of air pressure in the tank.. the evap system runs this air pressure through a carbon filter and into the intake tract so the gasses are combusted in the engine, rather than spread to the atmosphere.
At least, that's how I understand it.

As far as length you need from the fuel rail to the fuel tank, it really depends on how you plan to route it; my only suggestion is to take some rope or string and route it like you want to route the line, then measure how much you will use.

If the GT-s feed and return lines are not the same diameter (I've never actually compared them myself, or remember if I actually read about it), you could run into problems with low volume of flow to the engine, resulting in lean/detonation and premature pump failure, or you could end up with not enough volume of flow back to the tank which could end up in rich/leaking/cylinder washing.

arvin429
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Re: Fuel Line help

Postby arvin429 » Mon May 22, 2017 7:17 pm

I've heard of people using the sr5 lines as the return lines though

arvin429
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Re: Fuel Line help

Postby arvin429 » Tue May 23, 2017 2:33 pm

Also I was changing my rear harness and the rear gts harness i got was a kouki while my dash harness is a zenki. Can they still work?

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jondee86
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Re: Fuel Line help

Postby jondee86 » Tue May 23, 2017 5:05 pm

arvin429 wrote:I've heard of people using the sr5 lines as the return lines though

I have heard of people not having any problems using the SR5 fuel lines for supply
and return. Just use the two larger lines. Also the GTS pump assembly should drop right
into the SR5 tank as the SR5 and GTS tanks are the same except for an internal baffle.
So if you are on a tight budget you might like to give it a try :)

You will need to make sure that hoses connecting to lines seeing EFI pressure either
have proper flared fittings or are clamped with at least two hose clamps to make sure
you don't get leaks. On the supply side the hoses must be EFI pressure rated... having
your car burn to the ground will spoil your day real fast !!!!

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Kitsunami
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Re: Fuel Line help

Postby Kitsunami » Fri Feb 09, 2018 5:47 am

jondee86 wrote:
arvin429 wrote:I've heard of people using the sr5 lines as the return lines though

I have heard of people not having any problems using the SR5 fuel lines for supply
and return. Just use the two larger lines. Also the GTS pump assembly should drop right
into the SR5 tank as the SR5 and GTS tanks are the same except for an internal baffle.
So if you are on a tight budget you might like to give it a try :)

You will need to make sure that hoses connecting to lines seeing EFI pressure either
have proper flared fittings or are clamped with at least two hose clamps to make sure
you don't get leaks. On the supply side the hoses must be EFI pressure rated... having
your car burn to the ground will spoil your day real fast !!!!

Cheers... jondee86


I'm going to be using my SR5 tank and lines in my swap using an MSD 2925 pump followed by a MSD 2924 filter. In order to do this, I have to splice at least the pump itself into the hardlines I'm pretty sure.

In leu of flaring the lines, would two hose clamps actually suffice?

Secondly, I'll have to run the positive wire to the dash harness (I'm sure I can ground it just about anywhere). Do you happen to know where that would plug into?

Image

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jondee86
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Re: Fuel Line help

Postby jondee86 » Fri Feb 09, 2018 2:12 pm

A proper screwed fitting is always going to be better than a hosetail or plain
tube end with clamps. But if you do a proper job, two hose clamps will work OK.
This is an ebay external fuel pump kit...

Image

They only use one clamp to hold the hose onto the hard line. The bump on the
end of the fitting is more to stop the hose slipping off, rather than to stop leaks.
The pressure side is the one to be careful with. Make sure the hose is EFI rated
and a nice tight fit on the hard line. CRC or similar makes it easier to slide on.

For the electrical side you should use a failsafe system as used in all 4AGE
powered AE86 cars. This is designed to stop your pump continuing to run after
you crash and you are trapped in the wreckage !!! Anything less is at your own
risk. The following sketch shows how the GTS factory AFM system works...

Image

The absolute minimum you should have is shown in the following sketch. This
does not have the failsafe feature, and will not stop the pump running if the
engine stalls in a crash situation.

Image

You can get a 15amp 4-pin relay (don't need 5-pin) with a blade fuse already
built into the relay. Hook the hot side up to the battery and run the relay output
to the pump. Take a control signal from a switched power supply such as the i
coil positive and ground the coil to the chassis.

I recommend that you grab a Circuit Opening Relay and wire it as per the first
diagram using the FC and STA signals. If you are transferring the wiring over
from a GTS donor, most of the wiring will already be in the car :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Kitsunami
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Re: Fuel Line help

Postby Kitsunami » Mon Feb 12, 2018 7:35 am

jondee86 wrote:
For the electrical side you should use a failsafe system as used in all 4AGE
powered AE86 cars. This is designed to stop your pump continuing to run after
you crash and you are trapped in the wreckage !!! Anything less is at your own
risk. The following sketch shows how the GTS factory AFM system works...

Image

Cheers... jondee86


Great info, sir! But for clarification, if i'm already running all GTS wiring in my swap, wouldn't I be covered? I thought the only difference between the rear harness were the two wires to the fuel pump, which I'd be running to the MSD pump vs the GTS pump. Wouldn't using the GTS wiring act the same in every other sense?

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jondee86
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Re: Fuel Line help

Postby jondee86 » Mon Feb 12, 2018 3:21 pm

Yuss... if you have full GTS wiring front and rear including the engine harness
and underhood fusebox, you should have everything you need already. There should
be a wire going to the rear from the COR to the location on the trunk floor where
the wiring for the fuel pump, fuel level and low level light all comes together above
the fuel tank. There is a chassis ground back there somewhere as well. The wiring
will need to be extended and/or relocated to reah your new pump.

You just need the wire from the COR to power your pump. This information is based
on what I found in the back of my car when I was changing an in-tank pump. Possible
that USDM cars are slightly different.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

jinx
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Re: Fuel Line help

Postby jinx » Thu Feb 15, 2018 10:43 pm

for my current ca18 to sr5, I used a complete oem 240sx fuel line cluster/filter (with a little bending/modifying)
Top quality. Can usually grab em from a scrapped shell, for free. I did