In tank fuel pump?

[ebrown0104]

Anybody ever do an in tank fuel pump on their car? I'm thinking of changing to an electric pump on my 77, and the biggest issue I can think of is where to mount the pump and not make it look like a cheap add-on. I think an in tank pump would be easy to incorporate - just shorten the feed tube on the sending unit, clamp the pump to the end, drill a hole for the wires (and seal up afterwards), and drop the whole deal back down in the tank. It just seems so simple for something that I can't seem to find any info on.

Let me know if this is a bad idea or not. As usual, thanks for any help!

[divace73]

I've thought of this as a substitute for a surge tank as I don't like all that extra plumbing in the boot (trunk)

[baltobernie]

Most submersible pumps I've seen are for fuel-injected engines and are unsuitable for your car.

Fiat did not think it looked like a cheap add-on when they made it standard equipment. The Facet-type pump can be equipped with a pre-filter; very wise on a 40-year-old gas tank. Besides .. the pump is under the trunkboard and out of view

[bradartigue]

What's wrong with the mechanical pump ?

[lanciahf]

Alfa Romeo Spiders from 1980 on used a low pressure in tank pump to feed the main pump. The part is actually an ACDELCO pump. The pump is a low pressure at 1.5 psi. On my old Alfa Spider when I removed the Spica Injection I used only the in-tank pump to feed the dual webers. It was such a nice simple clean setup.

Do a google search for "Alfa Spider in tank fuel pump" and you will see many results. The only problem I see on the Fiat is a bracket to hold the pump and the wiring.

[ebrown0104]

I just replaced my mechanical pump and it's working fine, but over the winter I'm going to be doing a mild engine rebuild and eventually going with a set of IDF's (I have a DFEV right now). From what I've read, the IDF's are very sensitive to fuel pressure and I figured an electric pump with return-style regulator would be the best way to make sure they're getting constant pressure and volume. I like the idea of an in-tank since they're quieter and less likely to overheat, and also because they're not visible once installed.

I checked out the Alfa fuel pump, and it looks like an Airtex E8778 would be the one. It's 6psi max, and as far as mounting it I was planning on replacing the plastic return tube with a metal line and then clamping the pump to that. The last hurdle to clear is to make sure that it would fit into the sending unit hole in the tank, but it should be fine since in tank pumps are pretty small.

This is all in the future, though, since I'm planning on using the DFEV for a little while after the rebuild. The idea, to me at least, seems like it would be easier than mounting an external pump at the lowest point, since it would be hanging off the bottom of the car at that point.

[bradartigue]

Those pumps (in tank) were boost pumps for the FI systems. I'm not sure they're going to do what you want, or last as long as you hope. While they can produce the appropriate PSI they are designed to work with the pull of a 38 to 80 psi fuel injection pump drawing fuel from them...very little load on the in-tank pump.

In any case, mechanical or electronic, if you are concerned about fuel pressure regulation then you need either a very good pump or a fuel pressure regulator. A filter king or something like that will do a good job of both filtration and regulation.

My carbureted Alfas had single or dual Bendix type pumps - https://www.centerlinealfa.com/fuel-system/1186 - or look at Pelican Parts PEL-CB3193 - internally regulated. I would never use a square Facet "cube" pump without a regulator and prayer. The Bendix types don't make noise if you mount them correctly. If you want them to look like a real Bendix Pelican sells the stickers...

[lanciahf]

Alfa first used the in tank pump to feed their main fuel pump for the Spica Injection. The main pump was a high volume low pressure pump.

In 1982 Alfa switched over to Bosch Injection and kept the in tank pump to feed the now high pressure fuel pump.

In 1997 I switched over to dual webers and kept just the in tank fuel pump and ran the car in that configuration until 2002 where I sold the Alfa to Derk from Alabama on ebay. Derk flew in to the Philly airport, I handed him the keys and he drove it back to Alabama in the middle of July when it was 100+ degrees. A day later I got an email from Derk that he made it Derk was cool....

I think Alfa originally switched over to the in tank pump was that their fuel tanks for the Spica cars had the fuel outlet on the tank bottom, but the outlet was right near the muffler which caused some heat related issues.