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-   1964 To 1966 Flairbirds - General Technical Discussion (http://squarebirds.org/vbulletin/forumdisplay.php?f=26)
-   -   Fuel return line (http://squarebirds.org/vbulletin/showthread.php?t=22081)

HighwayThunder 10-19-2017 11:48 AM

Fuel return line
 
My 66 is at a shop being body-prepped and painted. When I get it back I'm installing a fuel return regulator. (I'll also be installing a crash cutoff switch to the fuel pump.)

The fuel supply line currently comes up on the left side of the engine and crosses over the top of the engine, connecting to the right side of the carburetor. Are there any considerations (safety, etc.) arguing against running the fuel supply line along the firewall (left to right) and connecting to the carb from behind the engine? This would reduce exposure to engine heat and simplify the installation of the regulator and return line.

Return line would run back to the tank parallel to the fuel supply line. Plan is to connect the return line to a connector installed on the sender unit. (That seems to be the easiest, safest way to do it: drain the tank, remove the sender, drill sender, screw on return line connector hardware, reinstall sender, connect return line, reattach electrical connector.)

Cheers,

simplyconnected 10-19-2017 06:47 PM

I wonder why you need a fuel return line with a carburetor?
At first, I thought you were running Electronic Fuel Injection that needs a return line because the system is closed and without a return line, any air would have to go out the injectors. IFI is under 55-psi, so running it anywhere is ok.

Then, I got to the word, 'carburetor'. Carburetor bowls are open to atmosphere, so any air in the line burps out in the bowl as a natural thing. Even with a regulator, there is no need or purpose for a return line. Fuel pressure is only at a few PSI with relation to atmosphere pressure.

Mechanical fuel pumps mounted on the engine must not overcome restrictions in the suction side, so a low fuel line before the pump works well. After the fuel pump, you can run the fuel line anywhere you like. They normally don't go to the firewall because there isn't much distance between the pump and carburetor. Suspend your fuel line away from metal and you will be ok. - Dave

HighwayThunder 10-20-2017 12:05 PM

I didn't mention that the fuel pump is electric (no matter). The reason I was planning to add a return regulator is that I'm still having what I think is a heat problem related to the fuel line. (I realize some on the forum disagree with that assessment.)

Everything I've done to date related to heat transfer has definitely lengthened the time it takes for the engine to die due to (what I still think is) overheated fuel in the line, but it does eventually crap out. The idea behind the return line is to keep cool fuel running in the supply line during idle (i.e., less demand causes the supply to slow, giving time for it to become overheated).

However, given your advice, I think the best approach is to start by moving the supply line to the firewall, and see if there is an improvement before even considering a return line.

"Suspend your fuel line away from metal and you will be ok." If I understand correctly you're suggesting that the line be mounted on stand-offs. Will do.

Thanks.

BTW, I'm looking forward to posting pics of the painted car.

Cheers,

Joe Johnston 10-20-2017 12:32 PM

As you mount new fuel lines, remember to allow for flex because the engine moves when driven. A steel line hard mounted from the engine to the firewall will break. That is why there is always a short length of rubber line going from the steel to the fuel pump, then steel from the pump to the carb. Be safe.

YellowRose 10-20-2017 01:24 PM

Fuel return line
 
2 Attachment(s)
Mainly, get that metal fuel line up off the valve covers or the engine block. Some people insulate it and move the line so that it is suspended a few inches off anything that is generating heat... Notice in the pix below that the hard line comes up from the fuel pump, runs behind the AC compressor, takes a right turn, under the snorkel of the air cleaner, takes a left turn behind it and another left turn into the carb. There is a standoff attached to the air compressor and one on the back side behind the air cleaner that keeps it stable and above and away from the valve covers and the block.

Here are a couple of pix of how my fuel line is run on my '59 Squarebird.

simplyconnected 10-21-2017 03:33 AM

Quote:

Originally Posted by HighwayThunder (Post 111861)
I didn't mention that the fuel pump is electric (no matter)...

Oh, but it does matter. It also matters where you mounted the fuel pump.

Here we go with partial info again, and it turns into a guessing game.

Did you mount the pump in the rear of the car?
Did you mount the pump in the front of the car?

Vapor lock is only created at certain heat AND pressure (or negative pressure). A long suction line may indeed provoke vapor lock under certain very hot conditions. (Didn't we go through this before?)
Rarely, can you create vapor lock on the pressure side of the fuel line regardless of ambient temperatures because the boiling point goes up with more pressure.

Modern cars never get vapor lock because the entire fuel line is under high pressure. The return line has little to do with vapor lock but more to do with cavitation that is drawn into the pump, even submerged. You don't have a high pressure pump.

Ray caught my meaning. Keep your fuel line lifted off of a hot engine. - Dave

scumdog 10-21-2017 06:21 AM

Quote:

Originally Posted by YellowRose (Post 111863)
Mainly, get that metal fuel line up off the valve covers or the engine block. Some people insulate it and move the line so that it is suspended a few inches off anything that is generating heat... Notice in the pix below that the hard line comes up from the fuel pump, runs behind the AC compressor, takes a right turn, under the snorkel of the air cleaner, takes a left turn behind it and another left turn into the carb. There is a standoff attached to the air compressor and one on the back side behind the air cleaner that keeps it stable and above and away from the valve covers and the block.

Here are a couple of pix of how my fuel line is run on my '59 Squarebird.

It appears your fuel line run all the way around to the rear of your carb and around it to the front whereas on my '66 it runs up from the fuel pump, heads behind the distributor and curves directly into the inlet on the front of the carb.

In '59 did Ford run the fuel line as per your picture then change it by '66 to be like mine?
Does anybody know??

YellowRose 10-21-2017 11:13 AM

Fuel return line
 
1 Attachment(s)
Tom, as I recall, my mechanic decided to run that fuel line that way instead of the other way as in your pic you sent. As I recall the input on the 1406 is on the passenger side of the carb. Here is what Tom said.

"Hi Ray, As per my post on Squarebirds regarding fuel line routes here is a photo of the fuel line on my '66, as you can see it runs up from the fuel pump, through the fuel filter and around the distributor then to the carb. Regards, Tom."

Here is the pic that Tom sent me.


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