Fuel Return

[Alex Datsun]

Is it really all that big of a deal not to run a fuel return with triples? Im going to run a return line but is there any pros/cons to not running one because I see (duals but mainly...) tripple webers and mikunis not running return line, not to mention makes fuel routing easier.

 

Thanks!

[ggzilla]

Weber and Mikunis (and carburetors in general) do not require a fuel return line.

 

Datsun fitted a fuel return line to 1) prevent fuel lock and 2) keep the fuel cooler to reduce evaporation at the carburetor. But not because the carburetors "need" a return line.

 

Whatever you decide to do, don't block the fuel tank *vent* line. That's the third fuel line coming up to the engine compartment from the tank.

[Just Joel]

I had to repurpose my tank vent line as a return line when my su's were acting up and overflowing. According to the guys at z therapy, su's don't work well with out it as are easily over pressured by the mechanical fuel pump... Don't think this applies to webers but thought i'd mention it. Oh and to combat potentially pressurizing the tank after repurposing the vent line, I gutted my wagon gas cap so the tank can vent outside (like the pre 69' models).

 

Later

Joel

[I'm BLUE]

I had to repurpose my tank vent line as a return line when my su's were acting up and overflowing. According to the guys at z therapy, su's don't work well with out it as are easily over pressured by the mechanical fuel pump... Don't think this applies to webers but thought i'd mention it. Oh and to combat potentially pressurizing the tank after repurposing the vent line, I gutted my wagon gas cap so the tank can vent outside (like the pre 69' models).

 

Later

Joel

 

Exactly and SU's are sensitive ( at least mine was ).

 

Webber's are VERY fuel pressure sensitive (DGV and DCOE ) <--- that I know of ,,, you WANT to run a fuel pressure return line as well if you have pressure spikes from a mis-matched electric fuel pump. The carter electric fuel pump is the correct electric fuel pump to run ( low pressure ).

 

Old american muscle ,,, quite a few of them never had a return line ,,, now people have thought twice about that part of the design and incorporate one as an "upgrade" since so many people are running off-brand and mix-n-match fuel system component's.

 

I might add ,,, now is a good time to put an in-line fuel pressure gauge while you're at it.(if you can afford , but it saves a LOT of headache when tuning triple webber's. )

 

happy trails !

 

Oh yeah ,,, if you don't have the carter electric fuel pump ,,, good luck trying to keep the webbers running right or even worse tuning them ! ( I found out within about 10 minutes my old ones needed the correct fuel pump as cheap/medium expensive pressure regulator's didn't work as claimed ... )

[goonfan]

I run triple 40's with a Holley reuglator and Carter pump. No return line, no problem.

 

Fuel is supposed to get hotter this way but I've never test it or seen actual evidence.

[Alex Datsun]

I run triple 40's with a Holley reuglator and Carter pump. No return line, no problem.

 

Fuel is supposed to get hotter this way but I've never test it or seen actual evidence.

 

Yeah i have a carter pump no fuel reg for now since it pumps a constant pressure for now anyways. Yeah i gues ill just run the return line to keep the fuel cool since my whole setup is improve small stuff here and there. Yeah im gonna put a fuel psi gauge when its all said and down btw anyone knkw where i can get a syncrometer for my carbs?

[goonfan]

You can pick up a Syncro here... If you haven't already. I wanna say it's $40

 

http://www.redlinewe...ynchrometer.htm

[I'm BLUE]

I run triple 40's with a Holley reuglator and Carter pump. No return line, no problem.

 

Fuel is supposed to get hotter this way but I've never test it or seen actual evidence.

 

If you have the carter electric pump there is 100% no need for the holley regulator.

or a regulator at all.

 

I wouldnt worry about the "fuel getting hotter" as much as a mis-matched fuel pump flooding/pushing fuel into the carb or blowing out the gaskets and creating leaks ( seen it) .

[ggzilla]

^^^ what he said

 

 

Fuel getting hot is not a performance problem, but is an emission control problem as it will evaporate more easily in the fuel bowl and could tax the evapo system or carbon canister.

 

Secondly, vapor lock is a problem on some Datsuns where the fuel piping gets a localized hot spot a vaporizes the fuel right there. Then the pump can't pump through it. Doesn't happen too often though.

[Z-train]

Fuel can never be too cold.

[goonfan]

If you have the carter electric pump there is 100% no need for the holley regulator.

or a regulator at all.

 

I wouldnt worry about the "fuel getting hotter" as much as a mis-matched fuel pump flooding/pushing fuel into the carb or blowing out the gaskets and creating leaks ( seen it) .

 

Hmm, that's not a problem I have. I don't doubt it can happen though.

[goonfan]

Fuel can never be too cold.

 

For an all out performance engine I would agree. We've probably all heard that w/o a return line fuel can get too hot but again I've never seen any actual proof, maybe there are some tests in one of my books and I just don't remember, lol.

 

In any case my setup works for me and would work for others too.

[Z-train]

No need for proof.Logic(and physics) dictates that a stationary liquid above a heat source will be hotter than a liquid that is re-circulating thru a cool containor of liquid.

[ggzilla]

Fuel isn't likely to get to hot in Bremerton, Washington, that's true.

[Z-train]

Hot is relative.

[zdorantes]

Webber's are VERY fuel pressure sensitive (DGV and DCOE ) <--- that I know of ,,, you WANT to run a fuel pressure return line as well if you have pressure spikes from a mis-matched electric fuel pump. The carter electric fuel pump is the correct electric fuel pump to run ( low pressure ).

 

I might add ,,, now is a good time to put an in-line fuel pressure gauge while you're at it.(if you can afford , but it saves a LOT of headache when tuning triple webber's. )

So I want to install the carter fuel pump but do you know whether its good for the stock fuel injection for 280z's?

 

Also I will be upgrading to webber's soon and if I do get the carter should I keep a fuel return line? How and which brand should I put for a in-line fuel pressure gauge?

[zdorantes]

You can pick up a Syncro here... If you haven't already. I wanna say it's $40

What's a Syncro?

[I'm BLUE]

So I want to install the carter fuel pump but do you know whether its good for the stock fuel injection for 280z's?

 

Also I will be upgrading to webber's soon and if I do get the carter should I keep a fuel return line? How and which brand should I put for a in-line fuel pressure gauge?

 

There is a carter brand LOW-PRESSURE high-volume fuel pump = meant for DCOE sidedrafts (webbers , etc)

 

Carter also makes an electric fuel pump for the 280zx EFI system which is much higher pressure = yes it's a good enough pump to run ;)

 

 

^^^ There is a HUGE difference between the 2 :)

[I'm BLUE]

What's a Syncro?

 

click the link posted ---> http://www.redlineweber.com/html/application_guide/redline_synchrometer.htm

 

used for tuning and more importantly easy to use.

[zdorantes]

How would you suggest buying dcoe 45's? I mean from what supplier (online or store)

[TENDRIL]

will the stock fuel pump have enuf  power for dual side-drafts? and feed them properly ?

[ThunderZ]

There is a carter brand LOW-PRESSURE high-volume fuel pump = meant for DCOE sidedrafts (webbers , etc)

 

Carter also makes an electric fuel pump for the 280zx EFI system which is much higher pressure = yes it's a good enough pump to run ;)

 

 

^^^ There is a HUGE difference between the 2 :)

Do you know what part number it is for the low pressure pump?

[russaroll]

Do you know what part number it is for the low pressure pump?

Carter 4070 Fuel pump with Mounting Bracket kit