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Installing new fuel tank  Rating:  Rating
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 Posted: 10-28-2006 06:46 pm
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jensen4u
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Hey guys,

I bought one of the new almunimum tanks from George a few month back and am now getting ready to install it. There is one difference between it and the oriinal tank. My original tank only had one connection on the side of the vent/return hub and the new tank has two. I understand the use of the two after looking at the fuel system parts explosion, but question wheather or not I can simplify from the orignal plumbing a bit. First question is do I need both the vent line to the carbon canister (btw I currently do no have a carbon canister) and the one that seem to come off the check valve? I believe the check valve is for vacuum prevention in the tank and the carbon is for pressurized fumes. Can anyone confirm this is correct. If it is why can't I just run both outside the car and terminate? Another question I have is do I need this return line to the tank from the pump. I do not plan to use an SU pump and am not certain that the recurculation is needed. It seems that either my old tank did not have this. Any help would be very appreciated. I am trying to gather all needed parts before I start.

Thanks,

jensen4u

PS

One last question is how did you fasten the vent pipe to the tank? The white plastic clips that were original are now broken.

 

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 Posted: 10-29-2006 04:24 pm
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Ron Earp
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Well, I'm not a JH purist but I know what can work on such a simple motor and setup.
I'd get rid of all the lines except the feed to the pump, and the vent for air at the top of the tank. I'd also use a standard Holley pump and get rid of the JH stuff. All you need to do is plumb in the line from the pump to the carbs, use a pressure regulator inline there and get the fuel pressure around 3-4 psi. Any extra tubes/vents on the tank I'd simply plug or connect them together.

As far as fastening the fuel hoses to the tank I'd just use standard hose clamps.

It is a simple car and your setup can be extremely simplistic.

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 Posted: 10-30-2006 08:33 am
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Harkes
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I agree with Ron. I also have the new aluminium fuel tank from Jorge. I plugged the vent line at the rear but did connect the line that normally runs to the front/carbon cannister. I don't have the cannister either, so mine is now sticking out the frame near the air hose that is connected to the vent/hub as well. i'm thinking about plugging it and get rid of the line.

You don't need the return line from the pump to the tank.

So like Ron said: all you need is the fuel line from tank to pump to carbs and the air hose from the top of the tank. Rest can be discarded/plugged.

I have a fuel filter between the tank and  a solid state SU pump (which still ticks!) and a fuel pressure regulater before the carbs in the engine bay.

Pay attention to the white plastic ring supplied with the tank which should seal the tank at the side where the sender unit goes in. Normally this is a rubber seal. The white plastic ring doesn't seal well and leaks. Use the rubber ring seal from your old tank and use the white plastic ring to fill the gap (you need to make it thinner..)

Good luck

cheers

erik

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 Posted: 10-30-2006 09:23 pm
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jensen4u
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Thanks guys for the feedback. Just to make sure I have this correct I will restate what think we have concluded. The small steel vent lin that goes to the carbon canister is not necessary. The 5/16 line from sort of checkvalve vent that bolts to the top of the hub should be vented just outside the trunk. I should pick up a fuel pressure regulator and install it in line and adjust to the said pressure. I should also either reuse or purchase a new rubber seal for the sending unit as the white plastic one from George is not one that seals well. I may consider haveing one made at a gasket shop...thoughts??? Other than that there is no need for the return line and I should install a good quality filter...I have already purchased one larger and two smaller glass filters for each carb. Anything else I have missed??

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 Posted: 10-31-2006 01:11 am
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Jim Ketcham
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I don't quite agree with the advice given above for your new tank installation. 

I believe clarification of the function of each line is in order for you to make a decision on whether to eliminate it or use it.

The top line out of the cap on the top of the tank is a pressure relief line.  The cap is a pressure relief valve and is a safety item.

The line that attaches to the rear most port on the tower on the top of the tank runs to the carbon canister.  Its function is to direct evaporative hydrocarbon emissions to the charcoal canister when the car is sitting in the sun or warmed and the fuel vaporizes.  When working correctly, the hydrocarbons are then sucked back into the carbs and burned when you start the car, thus purging the canister for next time.  It is one of the few emission devices that does not rob your engine of performance and really is good for the enviornment.  If you decide to not use the carbon canister and vent these vapors to the atmosphere, just make sure it is done away from a source of ignition (not under the hood).

The second line that attaches to the top of the tank is NOT a return line.  It is an antisyphon line.  It has an internal check valve that prohibits flow from the pump outlet to the tank (thus not a return line).  It allows air (vapor) to be drawn in to the line to the carbs if the pump is not running and a syphon forms if the carbs are lower than the fuel in the tank.  It is a safety feature, that I understand, was added after car fires in vehicles parked downhill.

Regards,

Jim  

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 Posted: 11-01-2006 02:34 pm
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jensen4u
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Two additional questions

1. Two choices of fuel pressure regulators are 1-4 psi and 4-9 psi. My jensen currently has strombergs on it, but just until I get my set of dellrotos rebuilt. Which regulator should I go with? (BTW the fuel pump I have selected only has an output of 7 psi) Please confirm this is enough.

2. Is there a way to verify the anti-syfphon check valve is working properly berfore I reinstall it?

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 Posted: 11-02-2006 02:57 am
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Mark Rosenbaum
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With Strombergs, fuel pressure at the carb fuel inlet tee should be 2.5 to 3.5 psi.  IIRC, with Dellortos it should be a bit lower (2.0 to 3.0 psi, I think).

Unfortunately, I don't have an answer to your anti-syphon question.  Maybe if you cross Jim Ketcham's explanation with some experimentation you can come up with a good idea of what's going on.

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 Posted: 11-02-2006 02:59 am
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Jim Ketcham
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1) Dellorto's and Strombergs use the same pressure of 2 to 4 psi.  The fuel pump you choose should be low pressure HIGH VOLUME.  I run the SU solid state pump with no regulator and have had excellent luck in both my JHs.  I run Dellorto 45s and one is a 2.2L stroker.  I also have used a low cost FACET pump reliably, again with no regulator and monitored pressure at the carbs proved to be excellent.  I am not quite sure of the benefit of a fuel regulator if you get a proper pump.  To me its another set of connections and additional hardware to mess up.

2)  The anti-syphon check valve is a little metal check valve hidden in the hose that tees from the pump outlet to the top tank return.  You can remove the hose and try blowing through it.  You should only be able to blow through it in one direction.  Make sure you replace it in the correct direction, that is "no flow" towards the tank.   I believe many complaints of low fuel pressure are a result of people replacing this hose and not realizing that there is the check valve inside.  Without the check valve the pump dumps fuel back into the tank and has trouble supplying the carbs.  If you replace this hose you can remove the check valve from the old hose by cutting it out and place it in your new hose.  If you do not have a check valve you can probably find one or something similiar, as they were common in many vehicles.

Good luck,
Jim

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 Posted: 11-02-2006 03:47 am
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jensen4u
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I am really confused now about ths anti-syphon check valve. The reasons I am confused is...

Delta mention this line as a return line and an orifice for metering the return fuel. This is to keep fuel moving through the pump. They did not mention anything about a checkvalve in this line.

I thought the anti-syphon checkvalve was the item that bolts to the top of the return/vent hub as it is spring loaded as a checkvalve would be.

It appears my original tank did not have this line what so ever as there is not a connection point per the shop diagram for this line.

Can someone please help clear this up for me as I thought I was pretty close to having this completely understood.

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 Posted: 11-02-2006 04:30 am
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Jim Ketcham
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You might want to look at the parts manual diagram.  I do not have one in front of me now, but I believe if you look at the names of the various components shown in the diagram you can figure it out.  For example, the spring loaded valve on top of the tank is called "pressure relief valve".  The line from it to atmosphere under the trunk, "pressure relief line".   The line from the tee after the pump to the top of the tank, "anti-syphon line".

You will notice that the "orifice" I believe you are refering to goes in the line to the carbon canister.

The SU style pump does not run continuously so does not need a place to dump fuel back to the tank.  That is why you hear it thump at different rates.  To test this just turn the ignition key to the on position.  You should hear the pump thump rapidly and then slowly and then stop (assuming your fuel system is in proper working order).  It regulates the pressure via a diaphragm and spring internal to the pump.  That is why you do not need an additional pressure regulator or a return line to the tank.

I am sorry if I made this sound complex.  It is not. The problem is my inability to explain it clearly.  Simply stated:

We have a fuel line to feed the engine at 2-3psi via a self regulated fuel pump.

An anti-syphon line teed into the above fuel line to the engine to break syphon when the engine is lower than the tank.

A vent line to equalize pressure to atmosphere in the tank (via the carbon canister)

A pressure relief valve and line to dump fuel if for some reason the tank builds up excessive pressure.

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