I am sorting my fuel system out at the moment and i can go one of two routes, the first is to fit an External Pump (somthing like a Aeromotive) but to do this i must weld a sump into my stock tank. The second option is to fit twin in tank pumps, i have heard of this done but have never seen it.



Is there a write up or has any one on hear dont the twin pump mod on there Rx7? i just want to know how easy it is to do and what pumps are the best to do it with?



Thanks.........Chris

You just need two pumps, each with a filter, and a small distribution block to merge them into one. 2 walbro pumps would do, but 2 stock fuel pumps could also work.

So its as easy as mount the two on the Assembly and plumb them in.



Do they go throught the hole in the top of the tank?

https://www.mkiv.com/techarticles/fu.../DualPumps.jpg



there is at www.mkiv.com an article on the dual pumps, its "fuel pump tests?" it looks really simple



mike

so 2 stock tii fuel pumps, would equal a 255lph Walbro?

it would equal more than a 255 lph walboro.



Either way, the aeroquip fuel pressure regulator has 2 inlets. I am going to run 1 pump to the primary, 1 pump to the secondary(RAILS) and then use the aeroquip FPR as the "Y". They'll go back to the pump via the charcoal canister hard line(or you can run 3 meters of -6 hose) and then I'll tap the fuel pump assembly with a bulkhead fitting for the return IN...

hey using the charcoal cannister is a great idea!



mike

if you still have one :redface:

the line is there, right?



mike

I am just checking out all options, How would you wire it all up? if i used the stock wiring and just split it would'nt that drop the Voltage going to each pump? and if i Relayed it then it would get 12v all the time? would this cause any problems?



I like the Idear of having two completely split fuel systems, it would'nt be that hard to do but why would it be better to do it this way and not just link the two and keep the single feed?



The best bit is i have two Welbro 255 pumps doing nothing and this would make a quite good in tank set up but i want to make sure there is'nt going to be a problem with the power feed. Doing it this way i can keep the Parrel set up i have just fitted too.

This is the Fuel sytem i have fitted, its just got 2 more Injectors.

thats how my system is about to look, just need to tap the damn fuel rails or buy some tapped ones. btw how did you tap your fuel rails.

I have had new ones made for me (i'm doing a 20B)

I got a Question,



How do you wire it up? i was thinking if i conected both pumps to the stock supply would'nt there be 12v total and that would be split between the two pumps? or does it not work like that (I'm not big on wiring) I was thinking of useing relays to make sure both Pumps got the full 12v at WOT but that would cause the pumps to be flat out all the time, so it would mean the pumps are on at there peak all the time so i would have thought they would wear out quicker? and be more noisy.



I would like to hear your opinion as wiring is not my strong point and i may be wrong and it would be ok on the stock wiring?



Thanks

it looks like they had it wired so it used the stock power feed but i think that would be a weak point?

having the pumps full on, full time is not a problem though



mike

So if i wanted to be on the safe side i could relay the pumps and have a constant 12v with a good quality Rising rate fuel reg with no Problems?



I have just heard storys about the Pumps overwelming the Regulator and running very rich on idle?

yes to number 1, and number 2 it might if you have the stock regulator it minght, if you have an aftermarket regulator you should be ok



mike