New Fuel pump

It should read the cat would not start..

You should be able to turn the key and get fuel. However, I'd get rid of the glass fuel filter. The threads holding the ends have been known to disintegrate over time causing a significant fuel leak over all sorts of hot surfaces.

It requires a certain amount of pressure to flow a certain volume of fuel through a filter. On the suction side of the fuel pump all you have is the head pressure of the fuel tank, which decreases as the level decreases. For this reason the fuel filter belongs on the discharge side of the fuel pump. A suction filter would have to be very large to allow enough fuel flow at higher rpm & engine loads.

Your fuelish friend on the PIBB, George

Thanks guys. Since my filter is between the tank and the fuel pump and it is prone to faliure should I simply remove it and install on on the discharge side? Any recomendations on type/part number for this new filter?

George, Bowing to your superior mechanical knowledge, what do you think of the argument that the filter should be on the suction side to prevent pump damage for foreign objects and on the plus side only be subjected to pump suction pressure vice discharge pressure? Also, isn't the head pressure only applicable if you take suction directly off the bottom of the tank i.e. no dip tube?

AJ, I've seen the Fram G2 for 5/16" lines or G3 for 3/8" lines recommended. You can go hog wild and get some pretty pricey fuel filters. Any quality filter will do.

Husker, keeping me on my toes heh? LOL

Once fuel starts flowing out of the fuel tank via the "dip tube" a syphon is created. The pressure at the suction of the pump for a given flow rate will descrease as the level in the tank decreases because the syphon must lift the fuel higher.(as the milk shake gets empty, you have to suck harder on the straw)

Where I am coming from in my advice is to use parts as they were designed to be used. I am also assuming that your engine, being installed in a Pantera, will be run "hard" occasionally, and this is where problems will arise. Let me explain:

It requires a certain differential pressure to flow fuel at a certain rate through a fuel filter. A fuel filter designed to operate on the discharge side of a fuel pump will create a certain pressure drop, like a restriction, in order to flow fuel at the maximum rate it was designed to supply. A greater pressure drop across the filter can be tolerated on the discharge side of the fuel pump because the pump was designed to operate with back pressure on that side. The reason the "filter first" configuration can possibly lead to problems is the fuel pump is not designed to operate with a restriction on it's suction side, with a pressure significantly below atmospheric on the suction. As the flow rate increases the pump will reach a point where it can no longer sustain the drop in pressure (vacuum) required for the fuel to flow at the rate that is being demanded by the engine and the fuel pumps discharge pressure will begin to drop.

A filter designed for the suction of a pump, designed to flow let's say 90 gph, would be physically larger. Perhaps twice the size of a common fuel filter or more, in order to reduce the differential pressure (pressure drop) at max flow rate in recognition of the fact that the pump is not designed for a restricion on it's suction.

The pump can pass some debris, it is far better to put the filter on the discharge side of the pump where everything was designed to operate. If the pump & filter were designed to operate in the "filter first" configuration there would be no problem, but they weren't. Of course, if all you do is cruise in your car & never tax the fuel system, you will never detect a problem with the fuel filter on the suction side. The problems will arise as more demand is placed on the fuel system. Finally, I suppose it would be possible to install a very large filter between the fuel tank & fuel pump and keep the pump operating within it's design parameters. This filter would have to be large enough that the differential pressure at max flow rate is kept minimal, since the fuel pump was designed for no restriction on it's suction side.

I must throw in a disclaimer and say that if you've purchased an aftermarket fuel pump, and the manufacturer's instructions say to install a filter on the suction of that pump, then please do so, install the exact filter the manufacturer has recommended. If you are running oem parts, then install them in the configuration they were designed to be operated in. Always adhere to the manufacturer's instructions.

If you've just screwed a banjo fitting into the bottom of the fuel tank, I would agree to temporarily running a filter on the suction for the first tank to catch the extreme amount of debris that has been collecting on the bottom & will now flow out through the new bottom feed on the tank, but after that first tank that filter should be removed.

The classic hot rodder's fuel filter is a Fram G15, for 3/8" fuel lines. To feed a 500 bhp motor you would need to run 2 G15s in paralell. There are many other options for fuel filters, just keep in mind the filter must be designed to flow fuel at a rate sufficient enough at system pressure to feed your engine under load at max rpm. Most of the quality filters provide that flow data, for instance Fram provides that data for its performance series of fuel filters.

My final thought, your fuel system must be able to provide enough fuel to supply what may be demanded by your motor under any and all circumstances. For instance, it would be incongruous to build a 500 bhp motor & provide fuel through the oem pump & filter. It would be similarly incongruous to install a 120 gpm fuel pump and install a 60 gpm fuel filter on it's discharge.

How'd I do?

Your friend on the PIBB, George

George, Well done, well done. So the bottom line would be at high flow rates the pump will lose suction resulting in a loss of flow?

It won't "lose" suction really, it will just hit a wall, i.e. a point where it can't pump at a higher rate.

your fuelish friend on the PIBB, George