ALFAGTV6.COM

[matt]

Hi there i just wanted to know if anyone had experience with electric fuel pumps in carby applications.
I've got a bosch fuel pump similar to photo to be used in a blow thru turbo set up and wanted to know if i need a small scavenge pump to my alfetta/gtv fuel tank to feed the main pump?
I see on milanos/75 an GTV6 no scavenge pump used maybe because the pick up point for the pump is at the lowest point of the fuel tank.
In alfetta/gtv pick up point is low in tank but exits the tank about half way up making it a bit harder for the pump to 'suck' fuel. I think these pumps although high press/flow etc don't 'suck' fuel too well therefore maybe i need a scavenge pump with an alfetta/gtv tank to feed main pump????? or maybe not?????? anyone with experience in this???

thanks Matt

[Barry]

Matt,As long as you mount the pump at the same level or lower than the pickup,it will work fine.Follow the mounting as per the gtv6 and it will work..
Unless you have a mege hp setup,lift pumps and accumelators are not needed here..

[MD]

Hey Matt,

What I woud like to add to Bazza's comments is that carburettors unlike injectors do not like high pressure fuel feeds. As a matter of fact they prefer the opposite. 1.5 to 2 lbs of pressure is all they want and you need a pressure regulator fitted to the line to make sure that it stays that way.

If you don't, you are asking for problems. Personally I think that Bosch pump is way too high pressure for the job.

[Maurizio]

On my spider I'm running a bosch pump and carbs. (It was converted from spica to carbs by the previous owner). The car ran like a pig, because of the the high pressure.
What I did is mount the fuel link on carb 1 to feed carb 2 also on carb 2. From there the fuel goes onto the return line towards the tank, runs great since then.

[matt]

Thanks Barry, I'll mount it just like on GTV6/Milano below the pickup level in fuel tank.
MD i need the high pressure to overcome boost pressure in blow thru turbo set up here, sure the carby only wants to see 4.5psi max of fuel press and i'll set the regulator i've got to this but the fuel pump has to be at a pressure higher than boost otherwise i'd blow all the fuel out the float chamber under boost. So if for example i had 15psi of boost the carbies need to 'see" 18 - 19psi fuel pressure, the trick is the reg'. The reg' has a boost reference port so no boost carbies see 3-4psi, with boost they still see 3-4psi its just 3-4 psi higher than whatever the boost is at the time. Well thats the theory anyway...........its prob going to be a pain in the ass to set up, but i'll take it to someone to tune.
Maurizio can you please explain more, i thought/convinced myself i was n't going to need a return line. I thought because carbies have float needles to stop fuel filling the float chamber when full i wouldn't need a return line like on fuel injected cars. The photo i've got of a turbodelta engine on the carby that feeds cyl 3/4 its fuel line stops at the carb, just like on N/A engine. Maybe the float needle springs are stronger on turbodelta carbs to fix this?????where as N/A carby float needle spring overcome by higher fuel press and floods???? Did it run like a pig because the HP pump was flooding float chamber, or generaly running really rich?????? what psi was set? I'd be really interested to hear and did you have to make up the return line/tank fitting yourself or spica 'injection' system already had this??
Thanks Matt

[Maurizio]

Matt,

it ran really rich, spica has already the return line.
Never measured the pressure, it was a not to scientific aproach, added the return line to the carbs and it runs great.

Saluti,
M