Fuel pump mounting....how far is too far?

[FLYNAVY30]

I'm running a carb'd set with with a return style regulator and a Mallory pump but the best mounting location I can find is the frame rail just in front of the rear tire....is that going to be too far from the tank? I know you want to have it as close as possible, but with exhaust routing over the rear end, this is by far the easiest and coolest place to mount it....thoughts?

[Matt Cramer]

Depending on the shape of the pump - can you fit it on the end of your sending unit? I managed to pull that off with a Walbro.

[FLYNAVY30]

No, not a chance, this is a C20 suburban so the sending unit is about 2 inches from the underside of the floor pan. Plus it's a Mallory pump that's about the size and shape of a Budweiser tall boy....and it needs to be mounted upright

[BR3W CITY]

9/10 times if your further than about 20" from the pickup you can start to get in trouble. Even with the lower psi pumps for the carbed setup, you still have to suck the fuel a good distance from the sump to the actual pump. Its like the exact opposite of head pressure. The further you get, the amount of work the pump has to do to move the fluid 1inch starts to exponentially increase. These electric pumps are designed for head pressure, not suction pressure.

Where is the pickup point? You might look at running an in tank, finding a suction pump (they DO exist), or switching the pickup point lower on the tank with a sump, and then mounting the pump nearest to that.

[FLYNAVY30]

The pick up point is the factory sending unit in a new tank. I just measured where I mounted the bracket on the frame, and its a good 32-36 inches from the sending unit so Im guessing thats not going to work. Getting a lower sump and /or running an in tank is not really an option as I dont have the time to or money to worry about dropping this tank and getting an aftermarket tank or buying a high dollar in tank pump.

I did find another location that may work that is inside of 12 inches from the sending unit, and about level with the tank. That of course will result in redoing all the work I did today, but I guess they wouldnt be called "project cars" if they went together the first time.