I got one for you guys... I am curious if this thought can be done. I am thinking that my intank fuel pump is not picking up and supplying a constant pressure... so I bought an external “inline” 255lph fuel pump. My question is can I hook this up in line before the fuel filter and just tie in to the wiring of my internal fuel pump? Both will be ran off the relay and turn off and on at the same time. I do not want to drop the tank and take the internal one out! so my options are to hook up the inline pump with the internal and let them both pump... or just disconnect the internal leave it lie and just use the inline one pump though the dead intank one to supply me pressure.
I read that you can run two in tandem of each other as long as the one in the tank still flows. It will actually take some load of having the old intank one pump pressure to the rail.

 

If you wired them together they would be fighting each other for juice. But yes, you can have two pumps. People run booster pumps alot for high horse or nitrous applications. Now if you just left the intank pump there without being ran, the inline pump might be overworking itself trying to suck the fuel thru the old pump. Which would shorten its life.

 

I really don’t know how the pumps work, but if the intank one is still flowing like it is now, would the inline one really be hurting trying to pull though a non plugged up one that is just sitting idle?
Tell me if I am wrong... but the both are 12V and ran off the same relay. If the voltage is constant and consistent 12V how are they fighting for juice? Would the added amperage blow a fuse adding the second pump?

 

The added amps might blow a fuse yes. Just like if your trying to run a bunch of lights/radios/etc off of one circuit. It would blow the fuse. If you are saying that your intake is not running like it should, then it is on its way out and will stop working eventually. Then you would be trying to suck through a dead pump.

 

Typical to run intank pump to a surge tank and have 2nd pump pull out of there

 

.. Another choice would have been cut a hole in the trunk floor for easy access to the intank pump...