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Discussion Starter #1
Today's rabbit hole....

Story first, question starts in second paragraph.

First off, I was out cruising around in m y '67 Duetto today and when I pulled into the driveway, the smell of gasoline was significant. On inspection, there were gasoline drips on my drive where I pulled in and about a cup of gas under the fuel tank where the fuel line connects. Looks like either the fuel line cracked or a connection came loose. I threw an oil bucket under the leak and am going to go out in a little while to figure it out. The leak slowed but I've got about a quart of gas under the car in about an hour. That fuel line is only a couple of inches from the exhaust, so I guess I'm lucky.

This might be my opportunity to make a few changes. The guy who sold me the car included the original, relined and repainted gas tank and the thing looks beautiful. It has the attached filler pipe and no vents. The tank that is in the car is for an injected engine (probably the '73 that donated the engine). It has an unused return vent on top in the front of the tank, and a vent as part of the flexible filler tube. The filler on this tank is multiple pieces and includes a piece of rubber hose. I do not see any fuel lines running out of the top of this tank, which means there is a line coming out of the bottom of the tank someplace. Not sure at all how that works yet.

The car has an external in-line fuel pump somewhere along the line. I've been under the car a couple of times but keep forgetting to locate it. It is very noisy when I first turn on the ignition but it quiets down. To me, noisy fuel pump means failing fuel pump, so I want to sort all this out.

Note that this car has a '73 2000 engine and Weber carbs.

OK, so here are the questions:

When did they drop the internal fuel pump and start with an external one (assuming they did)?
Is this tank, that is not using an internal fuel pump and has no fuel lines coming from the top of it, modified in some way to feed fuel through the bottom or is it just a later tank?
Does it make sense to put the original tank back in the car with an internal fuel pump and rerouted (as original) fuel lines, or should I just fix the line leak, replace the fuel pump and let it all go?
If I swap out tanks, will this 2000 engine be OK with JUST the in-tank fuel pump or do I need an additional fuel pump someplace?

I've attached a picture of the installed tank and the original one.

As I'm writing these down, I realize that there is probably more information about this elsewhere, but my initial searches didn't bring up what I was looking for about the external fuel line on my tank or whether I could just use an internal fuel pump or if I need a supplemental pump for the 2000 engine.

Your thoughts and experience with this would be greatly appreciated.

Thanks,

Scott
 

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Experts 'in the know' will certainly chime in, but I can tell you that if you are 'hearing' a noisy fuel pump on start up like I do on my 75 GT, then chances are it is an external electric pump (not an in-tank). It is most likely to be in the back, usually next to the wheel well on the right a good distance from the exhaust. The most common type installed on the 105/115 cars is Facet (red or black top) and those things have some kind of shut off valve to prevent carburators flooding, and (on mine at least) do not have a fuel return line back into the tank. Mine is usually more noisy when the fuel level is low (ie most of the time).
I didn't catch where your fuel leak is happening, but if it is upfront, then don't worry about the tank or fuel pump setup... look for the easy solutions first, a loose or leaky hose end beneath those horrific roma blocks, then move on to the fuel filter / regulator... if your electric fuel pump is indeed inside the engine bay then by all means, get it out of there... prompto...

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Discussion Starter #3
Hi Sbadaro,

Thanks for the quick response. The leak is a hose that I can see coming from the bottom of the tank. The fact that is is coming from the bottom of the tank precludes an in-tank pump since those are integral to the sender and go into the top of the tank with the fuel line coming out of them. There are no fuel hoses coming from the sender in this car and no fuel lines in the trunk all, just a breather for the fill valve and an unused vapor return connector (see picture above). The fuel pump I hear is just in front of the right side rear wheel well, so it is probably just about where yours is. I just got the car into the garage (oddly, with no additional gas leaking) and plan on putting the car on jack-stands and taking a good look underneath tomorrow.

What is really troubling me at the moment is that I've never seen a fuel feed in anything other than the top of an Alfa tank, but it looks like mine is external and lower on the outside of the tank (i.e. not in the trunk). I'm hoping I am wrong and that I just don't see it.

Anyone have any other ideas?

Thanks,

Scott
 

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Discussion Starter #4

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Your car originally had a mechanical fuel pump located below the distributor on the 1600. In tank pumps were introduced around 1979 I believe and was a supplement to the electric SPICA fuel pump located just behind the rear axle on the passenger side (high pressure). Since you have a 2L with webers you would have an low pressure (2-4 psi) pump. You don't need nor want an internal pump. A noisy pump is not unusual. If you think it's going bad, attach an in line gauge and check the pressure.
 

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Discussion Starter #6 (Edited)
I just confirmed. No fuel line coming from the sender unit. It is coming from underneath the trunk someplace. I also just confirmed I have what looks like a new Carter fuel pump (mounted to the front of the spare tire well) behind the axle and over-sized rubber fuel lines all the way up to the engine (the rubber is insulated near the engine compartment), which explains a little about the mentality of whoever put this system together. The Carter pump is huge, which explains why it is noisy. It seems overly complicated, so I am inclined to put the original tank back in, and re-do the gas lines. MUCH more homework is needed, though. I'll probably just fix the leak for now and add this to my list of things the car will get this winter.

Ideas and suggestions are welcome!

Thanks,

Scott
 

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Discussion Starter #7 (Edited)
GProcket,

OK, I get it about the need for the external pump. The choice of this Carter pump, along with the oversized tubing, is still troubling, though. I have an original sending unit with the fuel feed among the spare parts that came with the car. Before I do anything other than fix the leak, I want to try to understand why somebody would go to the trouble to do all this when it probably cost more than it would have to just mimic the original fuel delivery system.

Question: do any spider tanks have a feed that is not coming through the top?

Thanks,

Scott
 

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GProcket,

OK, I get it about the need for the external pump. The choice of this Carter pump, along with the oversized tubing, is still troubling, though. I have an original sending unit with the fuel feed among the spare parts that came with the car. Before I do anything other than fix the leak, I want to try to understand why somebody would go to the trouble to do all this when it probably cost more than it would have to just mimic the original fuel delivery system.

Question: do any spider tanks have a feed that is not coming through the top?

Thanks,

Scott
Yes, there are tanks that feed thru the bottom. The PO installed a SPICA gas tank. the return "vent" that you noted is actually a fuel return line. the line to the fuel pump should be at the bottom of the tank under the car. that's probably the location of your leak or the lines at the pump. The Carter fuel pump is a good fuel pump, but louder than a facet. I am using one for my build. The PO probably used a larger fuel hose because the fuel hose fittings from Carter are larger.
 
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