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How do I route this fuel line from my 1971 Dime?


guyster

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I removed two fuel lines from my 1971 510, 2-door. One goes from the bottom of the fuel tank to the engine bay, and feeds the fuel pump. Another goes from the detached upper reservoir canister "TO CRANK CASE." What does that mean?

 

I've routed the rear brake line along the transmission tunnel and don't see anywhere to route this mystery fuel line. Any reference pics would be appreciated.

 

Here's the manual drawing:  http://www.carpartsmanual.com/Portals/9/Figures/NorthAmerica/normal/510_016A_1_vga.png

 

If only I had another Dime to use as reference ...  :rofl:

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Not sure if you'll be able to see this picture since it's photobucket.. 

 

The line runs to this which is located in your engine bay. This is from a 521, but they look the same.

 

http://i258.photobucket.com/albums/hh275/Daniel_521/FlowGuideValve_zps6c1457b0.jpg

 

It's a evap valve. 

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It's a evap valve. 

 

Thank you!! I can't see the picture, but I can look up location of evap valve on the L20B (which I'm swapping in).

 

I'm BAFFLED by the fact that I can't see how to route the line. I mean, it came off the damn car!

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Only one is a fuel line to the fuel pump.

 

The other collects gas fumes from the gas tank as they happen when sitting or if it's hot out. The gas cap is sealed. The fumes travel to the flow guide valve which also has a one way valve, and into the crank case vent tube on the side of the block and into the engine for storage. The next time the engine is started the PCV valve on the intake sucks any and all fumes from the crank case so they can be burned. The flow guide valve also allows filtered air back into the gas tank to fill it as the gas level drops.

 

The L20Bs didn't have this set up. They stored the fumes from the gas tank and carb in a charcoal canister. Does the same thing just differently. One thing... your tank is vented through this line so don't block it off.

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  • 3 weeks later...

The L20Bs didn't have this set up. They stored the fumes from the gas tank and carb in a charcoal canister. Does the same thing just differently. One thing... your tank is vented through this line so don't block it off.

Hey Mike, I'm having a bit of trouble sourcing a fuel guide valve and charcoal canister for an L20B. Any sources you would recommend I try?

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  • 4 weeks later...

Many of the fuel guide valves on the left inner strut tower were pulled off & thrown away, as many emission control parts were! I have USED ones if you need, but I have never looked at HOW they work or if they work.  There should not be any raw fuel coming from the gas tank up thru that vapor tube, so you could potentially just leave it open, maybe with a small screen or filter on it.......OR route it to an air filter. If you need to have all that stuff hooked up for emission testing in your state, I can't help cuz I have never set that emission control stuff back up on a 510.......maybe Mike can guide you!!?? If no emission testing, bypass it all, BUT leave that vapor tube open!! 

 

You very likely can not buy a NEW charcoal cannister for the Datsun, but a charcoal cannister is a charcoal cannister on just about any classic car!  Moss Motors sells various British car cannisters, which you could potentially set up.

 

Hope some of this helps!

 

TJ

Denver

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You don't need both and the canister is better I think.

 

Where would I look for one?? Any wrecking yard.

 

index.3.jpg

 

This is marked

DIST... The ported vacuum signal from the vacuum advance is perfect for this. It tells the canister to open internally and allow the stored fumes to be vacuumed out the PURGE line.

 

 

PURGE.... Goes to intake vacuum. Stored fumes are sucked into the intake and cylinders and burned.

 

 

FUEL.... this is the fuel tank vent line. Some may also have a CARB connection to collect boiled off vapors from the carb. If not used seal it off.

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Kind of an aside to the main question, but is there any reason you couldn't put that canister under the car somewhere and run hard lines up to the engine? Only advantage would aesthetics of the engine bay, but I'm still curious.

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Everything under the hood is accessible and safe from the elements and damage.. Under the car not so much. The underside of the canister is open and covered with a filter to keep dirt out. When purging, air is drawn upward and in to replace the air/fumes sucked out. Aesthetics? I believe that if it serves a purpose it belongs there, if it belongs there it looks right.  

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If only I had another Dime to use as reference ... :rofl:

 

I have 3 Sedans and a Goon and still have trouble figuring that stuff out. That's an area i think a couple of my cars may be hooked up wrong. I been wanting to figure that out as well.

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The flow guide valve is just two one way valves connecting the gas tank vent to the air filter and the crankcase.

 

 

 

one way valve <from air cleaner only

 

gas tank vent.

 

one way valve> to crankcase only

 

 

Two conditions can happen...

1/ as gas is used and the level lowers a small vacuum is formed, air can be pulled from the air filter to replace the gas removed. It cannot be pulled from the crankcase

2/ while sitting, gas evaporates and builds pressure (0.4HG) that is vented into the crankcase but cannot go to the air cleaner.

 

 

If you can blow into the carb side (top hose) of the flow guide valve but not suck air through it... it would seem to be working.

If you can suck air from the crankcase side (bottom hose) of the flow guide valve but not blow into it.. it would seem to be working

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The flow guide valve is just two one way valves connecting the gas tank vent to the air filter and the crankcase.

 

 

 

one way valve <from air cleaner only

 

gas tank vent.

 

one way valve> to crankcase only

 

 

Two conditions can happen...

1/ as gas is used and the level lowers a small vacuum is formed, air can be pulled from the air filter to replace the gas removed. It cannot be pulled from the crankcase

2/ while sitting, gas evaporates and builds pressure (0.4HG) that is vented into the crankcase but cannot go to the air cleaner.

 

 

If you can blow into the carb side (top hose) of the flow guide valve but not suck air through it... it would seem to be working.

If you can suck air from the crankcase side (bottom hose) of the flow guide valve but not blow into it.. it would seem to be working

Why thank you Mike that explains it all, I would always get confused as to witch hose went to what connection on that valve. Now I should be able to get them the way they should be. I'm so glad your here.

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I think the flow guide valve is also marked. The valves are very slightly spring loaded so a small vacuum or pressure is needed to draw or blow through.

 

Storing gas fumes in the crankcase seems kind of... odd. I know the next time the engine is started the PCV sucks them out but a charcoal canister just seems neater somehow.

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Mike rocks!  We were plumbing all of this same stuff on a Triumph TR6 today at work, but a simpler system without that flow valve.  We are mixing different year components, so we have a simple early PCV valve set up. All we have for the FUEL side, is a vent tube from the gas tank to the charcoal canister in the engine compartment. That canister is also plumbed to the PCV system. The PCV system pulls from the valve cover to the PCV valve to the air filter......the charcoal canister is "T"'d into the PCV hoses, to the air filter. Basically, it draws crankcase vapors & fuel vapors back in thru the air filter, to be drawn in & burned off. 

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Here is how my 710 canister is connected and works.It's a '76.

 

 

With the engine off, gas fumes pushed from the tank through the tank vent line enter the canister and fall by weight down through the activated charcoal and are absorbed. The bottom of the canister has a filter cloth to hold the charcoal in but is open to the outside air. When the engine starts vacuum advance vacuum is used to open the purge valve (which has a very small orifice) and fresh air is drawn up into the canister from below as the stored fumes are pulled out by intake vacuum... not PCV. Now some may be connected to the PCV, but the vacuum can't be very strong as it's open to the block vent so I don't think so. Makes more sense to have a good vacuum supply. The purge valve has a restriction so it doesn't cause a huge vacuum leak. Mine has a hose to a fitting directly on the intake. Like I said maybe some have this connection to the PCV, but mine does not.

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  • 2 years later...

Hi,

 I realize this thread is a bit old - but I'm wondering what type of solvent I could use to try & clean up the inside of the valve flow guide.

    Also if I wanted to go to a canister type of emission; what year & model vehicle would I be looking at , then go to auto parts & ask for it.

      Thanks,

          Henry

   1971 510 SW

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I like the canister type that uses charcoal to absorb gas fumes. Don't care for storing fumes inside the engine block. My 710 has one. Gas tank vent line, hose to intake and one to the vacuum advance for the purge signal. The canister has all the correct valving. I think most mid '70s and up Datsuns have them.

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FYI the 240Z did NOT have a charcoal canister system.  We have a 1976 280Z, it DOES have a canister, so maybe the 1975 does too......??  All of the 1979-19783 280ZX's will also have a canister.  Using a Datsun/Nissan canister might simplify retrofitting on an earlier Datsun, cuz you will likely study the 280Z shop manual, which will have familiar wording, descriptions etc.  I would expect that you can find these parts USED in SoCal 😁

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August '73 on 260z and 280z had canister

The 1200 didn't but the '74 B-210 did

On the 620 the L16 and 'L18 didn't but the '75 and up L20B did.

On the 610 the L18 ('73) didn't but the '74 and on L20B did.

On the 710 the L18 ('74) did not but the '75 and on L20Bs did have the canister.

 

So '73 or '74 seems to be the cut off. No L16/18s had the canister, all L20Bs did.

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My 710 is a SW and the canister is mounted on the driver's side of the rad support but location isn't important.  Has 4 tubes, one sealed. It's marked Tank, Purge and Manifold. Tank is the vent from the tank. Purge is the vacuum signal from the distributor advance and is only on after the engine warms up and is above idle. The last line just goes to the intake vacuum.

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