Fuel pump advice?

[uk-maxie]

Hi all

Just looking for a second opinion if I could trouble you...

We recently bought an AC Delco fuel pump for both our 63 Polara (426MW) & 69 Sport Satellite (440) - initially to help the Polara's starting 'issues' (it always starts, eventually, but takes a lot of cranking) but thought we may as well fit one to the Satellite too.

The idea is just to use it to get the engine fired then turn it off, and run with just the mech pump. We think that'll work...

So far we've only started looking at fitting it to the Satellite, but I guess this question applies to both.

The info that comes with the pump suggests fitting a filter between the tank and the pump. We'd use one of the Napa Gold canister type filters as we have a spare that we got when buying filters for the 426.

So finally to the question...

Would the electric pump, plus an additional filter present too much of a restriction to the fuel flow for the mech pump to work efficiently during normal running (not starting) conditions?

I know somone who had one of these pumps on his Charger years ago, but has since removed it, and he said he didnt notice any restriction to the flow when it wasnt switched on. Going by that, I'd say an additional filter will be ok too?

Whaddaya reckon - cause for concern?

Thanks in advance :icon_thumleft:

 

[Meep-Meep]

If you tracked your starting issues down to lack of fuel in the bowl then I'd ask where is it going? Around my parts (Nor-Cal) the fuel isn't want it used to be and seems to cause drivability problems with carburetors, but I manage to get by with one Holley high output mech pump on my 440. Yes, it takes a bit of cranking if the car sits for a month but not too bad from my perspective so I don't worry about it. The more I think about it the more I like the idea of fuel injection!

Assuming the electric pump you have is a vane or gear pump they like to push rather than pull, so ideally they should have an unobstructed gravity feed to the inlet. Note: A filter with a lot of surface area on the inlet side may not be a significant restriction. The mech diaphragm pumps are more like positive displacement vacuum pumps where they displace fuel in the line and the ATM pressure in the tank pushes the fuel to the pump inlet to fill the void. Adding an electric pump in series with a mech pump has proven to be successful but if the electric pump stops it may very well cause a restriction to fuel flow.

That said any restriction to fuel flow may not show up until you are reaching the full potential of the engine. All the fuel from the tank enters the carb through two needle and seat assemblies (assuming one 4 BBL) that have orifices approximately .1" in diameter and at a pressure of about 5-7 PSI at low flow conditions. With the needles fully open the pressure can be 2-3 PSI or less but you are flowing fuel so it's expected. bottom line: If you maintain proper fuel level in the float bowl then you have enough.