[afterburn 549]

It is true a larger diameter water column equals more weight and thus more suction required on the vertical. However, we are usually siphoning more than drawing vertically as the pump inlet is at the bottom of below the bottom of the tank. (Depending on the specific install)

We do see a point of diminishing returns with regards to draw straw diameter. We have built custom units in the 3/4" and larger range and they work with varying results. 5/8" is about the practical maximum with really large pumps.

So, using the siphon as the general rule, it takes less suction to do the same job as gravity helps us draw the fuel by using the weight of the fuel. Yes, if the system was bone dry, it would force a longer draw, but that's not the typical case with these trucks.

The bottom line is the factory restrictive modules makes for far more work for the pump than does a larger inlet fuel line.

I am still not in favor of 1/2" lines on the pressure side of the pump as I am an old time drag racer and know the effects of acceleration on that larger fuel diameter, not to mention the fuel has to pass through the restrictive 12mm fuel filter and or VP inlet anyway.

But one thing is for certain, if you have a restrictive module and you are consuming enough fuel, you WILL make the pump work harder and it can and will create aeration/ cavitation in the fuel from the pressure drop. With regards to the non bypass setups, stock, Airtex, my 12V lift pump, Raptor, HPFP or whatever, inlet restrictions are a very real cause of this issue. And you can still have full fuel pressure while pumping mostly air. I have proven it in my own rig.

I am not telling you to buy a Draw Straw. I am telling you that you need to be sure you are fulfilling all the requirements of the complete fuel system. It starts in the filler neck and ends at the injector tip.

Dave. End of said Quote.


This is about a dodge Diesel pick up.
I say people are adding loads of work to the fuel pump (electric) when they go a bigger draw tube in the tank..........gets all emotional over there @ DTR,