[Firebob]

Just went thru some of this trying to get it sorted out. Apparently I can't pull enough fuel with the mech pump through the red pump when it's off. The idea of a check valve is interesting but depending on how it's all plumbed together I wonder if when the elect pump kicks in, if it wouldn't interrupt the flow of fuel as it enters the stream? Does anyone have a diagram they can post of how this would be plumbed? I have an idea but maybe there's other, better, ways.

[PontGuy]

This is what we are talking about.

Normal operation, electric pump off: Fuel gets pulled by the mechanical pump through check valve in bypass line.

WOT- electric pump on: The check valve keeps the fuel from flowing back through the bypass and into the tank.

Something like the valve in the link was what I was thinking about. Still not convinced that it would not restrict flow a bit when the electric pump is off since it says that it takes 2 psi to lift the check off the seat. But if rigged so the pump always comes on when the secondaries are wide open then it seems like it should work OK.

[Firebob]

That's what I'm talkin about. In my minds eye I had the check valve in the straight thru line and the elect pump on the Tee'd in( bypass) line. The design in the pic makes way more sense. Thanks for posting that. Now I just have to source two brass hose tees and a check valve and I'm in business.

[leeklm]

Yes, thanks for posting the pic. In my case, I think I am also on the "edge" with the mechanical pump and 3/8 lines. My 420hp 455 worked fine, but now adding a few more ponies. I like the simplicity (and relatively low cost) of adding a pusher pump that I can turn on when hitting the drag strip, and leave off when putzing around town. The pusher could also help out on that 100 degree day when vapor lock can be an issue. Of course we get like one of those per year around here...

For those that have done this, what brand/model of electric pusher do you like? paging through the summit catalog the edelbrock EDL-1791 looks like a decent unit for this purpose?

[jonmachota78]

Don't forget to run a prefilter for your electric pump. Especially if you choose a gerotor style pump as they don't pass debris and particles very well (100 micon screen or finer). Vane style pumps (noisey) are a little more forgiving but still need some kind of prefilter.

[Singleton]

Here's what I had in mind for my car. Use the factory located in-tank pickup for normal operation, and under WOT have the electric pump turn on that pulls from a sump welded to bottom of tank, since the factory pick-up could become uncovered during hard acceleration.

[ta man]

Originally Posted by Singleton

Here's what I had in mind for my car. Use the factory located in-tank pickup for normal operation, and under WOT have the electric pump turn on that pulls from a sump welded to bottom of tank, since the factory pick-up could become uncovered during hard acceleration.

I'm assuming the picture isn't accurate...the pump will be located behind the tank?

[Singleton]

Originally Posted by ta man

I'm assuming the picture isn't accurate...the pump will be located behind the tank?

Behind the tank?, no, but the pump/filter/line will be lower than the tank which will insure it always has fuel to it

[Tom Vaught]

1) If there is any fuel in the tank and the fuel level is higher vs the inlet to the pump the inlet line will always be full.

2) On acceleration, the fuel in the tank will try to move thru the the sump and push fuel forward at the same time that the pump is removing fuel in the line.

3) If the fuel pump is higher than the fuel level, now you could have an issue.

Ideally you would think that having the fuel pump in the back is the best deal (behind the bumper) but a hot electrical wire and a fuel pump close to a crash zone may not be the best idea. I am looking at the In-tank stuff now and putting the fuel pump inside of the tank vs outside. Liquid fuel does a great job on dampening noisy pumps.

Tom V.

[Singleton]

Wonder if you may have fuel starvation issues with one of those in-tank pumps under acceleration? With less than a full tank

[HWYSTR455]

Tom - When I was doing the homework on going to an in-tank pump, I couldn't find any that were rated for a carb setup. Regulators work within a certain range, so you can't bleed off like 38 psi. You find something in that works, please share!

.

[leeklm]

Look up the GM number for an 83 or so buick. They were carbed and ran an electric in tank pump. I used one when converting my s10 pickup over to a carburated v8. I used the entire relay schematic as well that ran a relay off my starter when cranking, as well as an oil pressure switch for safety.

[Tom Vaught]

Originally Posted by HWYSTR455

Tom - When I was doing the homework on going to an in-tank pump, I couldn't find any that were rated for a carb setup. Regulators work within a certain range, so you can't bleed off like 38 psi. You find something in that works, please share! .

The Aeromotive Regulator for a boosted engine can handle fuel pressures from 2-3 psi to I believe 50 psi without issues. It IS a return style regulator.

http://aeromotiveinc.com/tech-help/f...ked-questions/

"I want to convert my EFI engine to carburetion, how can I “knock the pressure down” coming out of my EFI pump? Does Aeromotive have a regulator for this application?
The greatest misunderstanding about fuel pumps is that they “put out” pressure. It’s best to think of the pump as a source of flow-volume. A bypass regulator creates pressure by restricting the volume flowing from the pump, thereby driving the pressure up to the set point. Once the pump has created enough pressure to open the regulator bypass, the regulator leaks just enough flow to maintain the desired pressure. The Aeromotive 13204 bypass regulator can flow enough volume on the return to handle most medium to larger EFI pumps, if the return line itself is large enough. Note: Most stock EFI return lines are too small for a carburetor conversion, creating more backpressure than the regulator. At minimum, carb conversions with a 13204 regulator will require a –6 AN return line for small OE pumps and a –8 AN for medium to larger pumps. Contrary to some conventional beliefs, the return line can never be too big if the regulator is right for the job. When in doubt, the bigger, more free flowing return line is the better choice."

This pump will install in the In tank style gas Tank easily:

http://aeromotiveinc.com/products-pa...-inlet-inline/

"For carbureted engines, with optimized fuel system components including a Aeromotive P/N 13204 Carbureted bypass regulator and AN-08 or ½” return line, it would be safe to allow for 900 HP forced induction (blow-through) and 1,100 HP naturally aspirated limit"

Originally Posted by Singleton

Wonder if you may have fuel starvation issues with one of those in-tank pumps under acceleration? With less than a full tank

The intank Gas tank has its own Internal Baffle system (around the fuel pump (just like OEM to take care of exactly your question about acceleration and less than a fuel tank of gas. I will try to get more info on the shape and size of the baffle.

Regulator:

http://www.amazon.com/Aeromotive-132.../dp/B000CFOL2G

This A2000 Carbureted Bypass Regulator has an adjustable BASE pressure from 2 to 20 PSI. (need a big return line though).



Tom V.

[beemergary]

Originally Posted by 61-63

You are probably aware of this but the dual quad 421 super dutys ran 3/8" lines back in the day.

I know nothing about quadrajets but for AFBs and Rochester 2bbls I've found that the seats under the needles in current manufacture sets are not large enough to allow the fuel pump to keep up with the engine on tripowers or dual quads when people want to go 1/4 mile drag racing; so I drill them out larger. That is the first thing I tell people to check when they start running out of gas part way down the track. But we're talking nostalgia type 400-600hp engines here and not all out modern racing engines.

I run a 421 super duty in my 63 tempest with 3/8 lines. You better remember to turn on the electric pump or there's a good chance it will go flat before the finish line. I'd say good to 6000 rpm's.

[Joel Koontz]

I run a 255 LPH in-tank fuel pump designed for a FI vehicle with a RobbMC return style regulator feeding Tri-Power Carbs. The regulator does just fine at reducing the pressure from 60+ PSI to 5 PSI or less. I have 1/2" lines to and from the regulator. I have been running this setup for over 5 years without any apparent issues.

[Firebob]

I unhooked my elect pump today until my check valve and bypass parts come in. I will run off the new Carter 6122 mech pump that I just installed. The elect pump ran a steady 5.5psi deadheaded to the carb. When I checked the gauge today running off the new mech pump it was a steady 7 pounds at idle. Just found that interesting.
Also set up a micro switch on my throttle today to activate the elect pump when the secondary linkage begins to move once I get everything else installed. We'll see how it all works out. It's all thru my 3/8 stock lines(just to get back to the original poster's question...sort of) and a 5/16 return line.

[HWYSTR455]

Thanks Tom! I somehow missed that info when doing my homework! Shame, since I already bought a tank for the clone, would have gotten an EFi tank if I had known!

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