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Discussion Starter #1
So I inherited someone else's incomplete project and I'm starting to see why it wasn't completed. It's chock full of problems.

PO had left the in-tank pump in place without any electrical connection and with a weak stepped hose, leading to a lot of stress on the fuel pump. I replaced the in-tank pump with a brass tube soldered into the socket that the pump used to go into, replaced both fuel filters, replaced the fuel pump, and still the flow is not good.

If I disconnect the hose from the feed on top of the tank and blow through it, I get a lot of back-pressure and no flow. Is that normal? Should it be free-flowing?

Can I expect a "self-priming" Mr. Gasket electric pump mounted mid-chassis to be able to draw fuel up through that elevated line and push it up to the carbs?

I see a serious kink in the metal fuel line in the trunk, right where it hits the center of the trunk and moves down under the car. Also, that line is quite rusty on the outside and I can't force a stiff wire through it. Can it be replaced without having to dismantle too much of the car? Is that kink normal?

Thanks
 

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Fuel pumps work MUCH better pushing, not pulling. Carbs only need 2,3,4lbs of fuel pressure. It is best to have a fuel pressure regulator installed. With the older cars with fuel tanks that have outlets on the BOTTOM of the tank, a chassis mounted electrical pump, (or engine mounted mechanical pump) is ok. When you are pumping the fuel UP out of the top of the tank, the job is more difficult. The Alfa part # for the in-tank pump is 605-18556, or you can substitute a Carter pump, available at NAPA, etc. Part # is P74067.
 

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My car is a 71 converted to webers, and therefore slightly different than yours because my tank has a bottom exit to gravity feed the pump. Your later car has a top exit tank, and Alfa added the in-tank pump to feed the main pump. Many pumps CAN lift fluids a certain number of inches (usually specified) and perhaps your 'Mr Gasket' can handle the amount of lift necessary but you are always going to have to pump enough to refill the hose until the pump self-primes again. I think the best approach might be to replace the in-tank pump, and feed it power from the positive wire feeding the main pump. Thus you will know it's on the right switched circuit without having to run (or trace) a wire all the way from the fusebox. I am not quite clear on where you are testing the flow by blowing into the tubing.... I doubt if you can create enough lung pressure to push the fuel the whole way from tank are to carbs through such a small tube, especially if there is a fuel filter in the line. However, I'm unclear on where you're testing the line.

The kink sounds like a problem obviously and I can't address that. However, I would still add the in-tank pump (Alfa thought one necessary which may be a hint), allowing you to leave Mr. Gasket alone rather than replacing it with a bigger pump with more self-priming ability. From the main pump to the carbs, it's about sufficient volume rather than pressure. The webers only require about 3 psi to operate so a pump that is too big ( big enough to lift all the way from the tank to self-prime?) then requires a fuel- pressure regulator, at more expense. I would think you could test the ability of your current main pump by disconnecting the feed from the tank, and using a short feeder hose from a gas can placed right next to the pump. That will help isolate the location of your problem.

Last thing: does your current pump have a built-in filter on the intake side? Many pumps do, and you will want to make sure that filter isn't clogged with debris from a (previously?) dirty tank.

Good luck and let us know what you find.
 

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Discussion Starter #4
I'll be putting in the Carter pump.

Mine had a small screen on the intake side instead of the kayak-shaped sock. Anyone know of an intake sock that will fit into the round well at the bottom of the tank? The screen will only work with the original pump.

Two other problems have sort of solved themselves. I pulled the metal line in the tank (not the problem) and even though my tuba-player's lungs couldn't push a lot of air through the line, I had forgotten about the in-line fuel pump which blocks the flow. Sounds like my problems will be solved by the in-tank pump.

And once again, I'm waiting for parts to arrive.
 

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I have been running a '79 spider on Webers with no in-tank pump for 15 years. The tube/hose between the pump intake and top connection of the tank will lose it's prime if you leave it for sufficient time. Most pumps work well when the hose is full of fuel but some are better than others at sucking through a hose that is air locked. I have tried several pumps and the Carter P4070 (not the P74067) is the best. It is a vane pump and it works better than Bendix pumps (P74067, Facet, etc). The downside is that it is noisy.

My redneck pump priming method is to blow into the tank filler with a leaf blower. It is effective.
 

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I converted my 74 Spica to webers. I retained the intank pump and added a Carter pump for the carbs. I also added a fuel pressure regulator to dial the pressure down to 2-3 psi.

If you keep the intank pump, you should also include the fuel return line to the tank so the intank pump does not deadhead and potentially overheat. I also include a barbed fitting in the return line that I soldered closed and then drilled a 1/16 hole so the fuel would bleed back into the tank and the hole allowed the pressure to be maintained in the system.

Different guys have found different solutions that work for them, like Ed.
 

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Discussion Starter #7
Return line

I hadn't thought about the return line, but that makes sense. I'll have to take a look at what I've got after the ravages of the PO, but I know there's a metal line parallel to the main fuel line which makes it all the way back to the tank. I'm pretty sure that's the stock return line.

There's also a rubber fuel line with a bolt jammed into it. I have no idea what that one is.
 

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I hadn't thought about the return line, but that makes sense. I'll have to take a look at what I've got after the ravages of the PO, but I know there's a metal line parallel to the main fuel line which makes it all the way back to the tank. I'm pretty sure that's the stock return line.

There's also a rubber fuel line with a bolt jammed into it. I have no idea what that one is.
Photos would be a big help.
 

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There's no problem with deadheading the in-tank boost pump. Given that it's 3 psi have any owners used just it to feed the carbs?
 

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John,
I chose not to deadhead the intank pump. It is an Airtex E8778 and rated at 4psi. Airtex said that it would be ok to deadhead but since the return lines were already there, I just added an orifice to the return and it works fine.

I know there are other ways to supply the fuel to the carbs, I wanted to do it once and not have to worry about it.
 

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Discussion Starter #11
Now you've got me thinking.

I don't want to deadhead the pump. Could I run a pressure-relief valve after the carb inlets instead of before them? That way, anything over 3PSI would go back to the tank and I wouldn't have to worry about reducing the flow in the return line since it would only recirculate if the pump got above 3PSI.
 

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What I did was install a Tee in the fuel line in the engine bay. One line comes from the main pump, one line goes to a King filter pressure regulator that feeds the carbs and the other line goes back to the tank. The line to the tank has the barbed fitting soldered shut and drilled out to 1/16" hole.

This lets the fuel bleed back to tank so in tank pump is not dead headed. It also allows the fuel lines to be pressurized so the carbs don't starve.

I put a pressure gage between the two carbs and adjusted the King filter until the pressure read 2.5 psi.

Cause I'm anal, when I built a new wiring harness I put the in tank pump and the in line pump on different fuses with 14 ga wire feeding each. Not necessary but could probably limp home if either pump crapped out.

You can see the photos on my refurbishing thread in the restoration section.
 
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