So I know this may be a stupid question especially coming from me, but I really don't understand why people don't run inline pumps. It seems to me like it would be a lot easier than the hassle of dropping the tank. I get that it's louder, but besides that? Please educate me.

 

Because it only allows the pumps to operate at a low pressure meaning the only difference in volume is going to be what a pump flows at half its normal pressure. A fuel pump might deliver 80% of its 0psi rating at 60psi, so if you run 2 pumps of the same size inline they each operate at 30psi, so 90% rating. So basically 2 pumps for only 10% more output.

Now if you install two pumps in parallel and not inline, you have twice the output, so a 100% increase in fuel.

 

Why couldn't you do a Y in your feed line and run 2 pumps and then Y is back down to 1? Is that the same as the parallel you stated above or no not the same concept?

 

Thats parallel. Inline is when the entire flow of one passes through another pump.

 

so one could in-turn do what i stated?

 

Sure, thats what almost everyone does. The only difference is where you put the Y. Most do it in the tank so you only see one feed line coming out.

 

so you could do it on the frame rail right?

 

The problem with external pumps is keeping the fuel pickup in the tank covered with fuel when accelerating, slowing, and not so much in trucks, turning. Also, most pumps lose a lot of capacity when they have to do any sucking whatsoever, so gravity feed with a large hose is preferred. If you can meet these criteria, you'll be OK.

 

Ok I understand now. I have been reading a lot about the "keeping 1/2 a tank of fuel problem" so it makes sense now. I never really thought that would be a problem but I thought wrong. Thanks everyone for the replies. I understand why everyone is concerned about going with a sump in there cells.