Ok, I plan on running 2 nippon denso pumps and wiring them to the battery with 8 ga. wire, my question is can i use the stock 12v lead that normally feeds the pump as a trigger for the relays??

 

YES! make sure good quality relays 2. Ron

 

Thanks for the advice Ron, I was thinking of 2 40amp relays, any recommendations on a specific brand or type?

 

hmmmm i have that setup in mind... actually gonna get it started this weekend....

Wont one relay be better then two? less things to go wrong, but if it goes wrong all pumps will stop altogether rather then having the ex secondary relays pump quit on boost....

I had in mind of gettin a solid state relay SSR, and use just one for both pumps. I am using a 8 mm line lead to....

what the stand on the relays guys?

Cheers

George

 

I run 1 (40A)relay and 1 (30A)fuse with my dual walbros. Hasn't let go so far.

The race car runs the same relay/fuse combo and it has an A1000 + stock fuel pump.

 

Mine also is a 40A relay with 30A fuse. Spend the extra money for a nice Bosch relay.

 

oh so true....

 

Any part numbers on the Bosch or any other automotive grade 40A relay? I went across the street to the local auto parts store and they didn't have a Bosch catalog. They did have a GP Sorenssen a/c compressor relay for the third gen but we couldn't figure out the amp rating on it. Are any of the stock RX7 relays 40A?

 

http://order.waytekwire.com/CGI-BIN/...100051+M37+ENG

 

I run dual 280 lph in tank nippon denso pumps and run them off a single 70 amp relay vs two 40 amp relays. I have it fused with a 60 amp inline glass fuse and triggered off a 12 volt switched source. I run 10 gauge wire on the heavy sides (battery and fuel pumps). Reason I didnt run two relays is because if one relay decides to take a crap, I wouldnt know and would loose fuel pressure under high boost=bad...vs. loosing all at once and car would just die...which it did because I was running them both off a 40 amp relay and trying to pull it through a 30 amp fused circuit, which it didnt like and melted things, lost all fuel pressure. So I rewired everything to handle it now. Each pump pulls about 25 amps Each at wot/full boost so makre sure if you go with a single relay, go with one that can handle the amps....this relay has really big power terminals to handle that kind of current, so you will have to find the right female wire terminals to fit.

 

I tried this on 2 FD's. I ended up switching to a different trigger on both. I even tried removing the in line resistor but still had voltage problems tripping the relays.

It seemed such a slick thing to do but I wouldnt do it this way again. Find a good trip wire and wire the pumps right the first time.

 

I had this thought when I first went to 2 pumps. I tried to have a elctronic monitor made that would light up when one pump dropped. But as it turned out the monitor didnt work and I lost a pump. I knew immediately as the fuel pressure drop made the car run like total crap.

Cool thing was I just modified the FPR setting to compensate and drove home on one pump (no boosting of course).

I run two wired independently now and dont worry much about one failing and me not knowing it. There is always that "at WOT" possibility but I quit worrying about that.

 

Im thinking of running dual walbro, and each pump supply a fuel rail. One going to the primary and one to the secondary.

Im thinking of running it off of one relay, 70AMP, stated earlier by BLitzed33. Please reconfirm.

BTW, Im thinking of fabbing up my own dual pump bracket. Are you guys using aluminum or stainless steel? Or does it matter.

 

I think they're redoing the web page as it's not working for me.

Anyone have a p/n for a 70A relay?

I'm currently running two 40A relays but want to switch to one relay. I use the 12V wire from the OEM fuel pump line as a trigger with no issues. I do have two batteries in the back PC680's, with thick gauge wire.

 

I just used 2 clamps to hold the pumps together...No fabrication required.



I did end up getting the top welded for the wire passthrough. Dont have a pic of that though.

 

The only bad thing about this type set up is that if you get a short in just one of the wires gong to pumps or if you have one pump go bad and start pulling mega current its going to have to draw more than 60amps before ti blows the fuse. The wire will probably melt thru before the fuse blows unless all of the wires in the circuit all the way to teh pump is rated to handle more than 60 amps.

The best way would be to have a seperate power wire for each pump that goes all the way from the pump to the battery with the appropriate size fuse and relay to handle one pump on each line. You could also do a larger single feed from the battery with a 60 amp fuse then go into a distribution block and come out with 2 power wires (one for each pump), each with its own relay and 30 amp fuse....which is what I did.

The most important thing is to size up the capacity of the wire with the fuse. If all you have is a 60amp fuse on the entire circuit then make sure all the wire running off that fuse is rated to pull more than 60amps that way the wire doesnt burn thru before the fuse.

Stephen

 

Thanks for the input stephan, that is a good idea. I actually have 10 gauge wire from the battery with the 60 amp fuse inline to the relays battery power terminal. Then a 10 gauge wire off the power feed terminal to the pumps wired together. Then run a fused triggered wire source and then just plain ground. As far as a short, the wires are routed so that there is minimal chance of chaffing through and shorting to ground...also they are shrouded in convoluted(sp?) tubing. If one pump goes, I will just have to deal with that situation when it comes up

 

DAMN!! I havent looked at this thread in a few days and it really blew up!! Tons of great info here, thanks everyone! So it looks like 1 Bosch 70 amp relay, 2 separate 8 ga. wires from the battery each fused with a 30A fuse to each pump is gonna do it.

 

I am also doing a twin in tank setup and was worried about one of the pumps failing. Do you guys see any problems with putting a pressure switch inline on the fuel line that would be hooked into a relay shutting down both fuel pumps if the pressure drops below a predetermined level? Just an idea.....I guess base pressure is much lower then it would at WOT making it difficult for it to read when a pump goes out.

 

i suggest anyone reading this twin pump thread should check out a recent thread entitled "fuel system goodies from Dsport."

howard coleman

 

https://www.rx7club.com/single-turbo-rx-7s-23/fuel-system-goodies-dsport-580508/

 

u might want to put some rubber between the pumps. i cant tell clearly from the picture if you had done so, but if you dont it will burn the pumps out.

 

Good stuff!

 

why will this burn the pump out?