HUGH

I am currently running a T04S .84 hotside, divided with a large street port. The fuel system is comprised of two cosmo fuel pumps (in tank) and a in line fuel filter. I am using a FueLab pressure regulator. the lines are -6an with jic fittings crimped on good for 5000 psi (not that it is needed.) I am using factory primary fuel rail with npt to JIC connectors and a RX-7.COM secondary fuel rail. 550's Primary and 1600's secondary. My problem is that when I start to open up the secondarys my fuel pressure drops off. I bumped it up temporarily to 42 psi (test only, as the dyno tune was set for 36-38 psi) hit the throttle, fuel goes up to approx. 64 psi than it falls flat on it's face to 20 psi or so. Any one have suggestions? I am figuring fuel pump issues. But why these results I'd think that a single cosmo fuel pump should be able to make the nessisary flow to create the pressure?

cewrx7r1

iTrader: (2)

Maybe only one pump is working and at a certain pressure the fuel backflows through the one not working.

Maybe a bad fitting within the tank leaking.

Maybe a bad FPR, or not properly connected.

Maybe ghosts in the fuel?

HUGH

Did some operating on the Fd this weekend. I replumbed from the filter to the primary fuel rail using -8 (1/2") fuel line. I was hoping to use -8 after the primary fuel rail inlet however the oil injectors seem to get in the way so I had to use -6 (3/8") fittings from the outlet of the primary to the inlet of the secondary. Outlet back to fuel pressure regulator is also -6. (Note I used steel fittings which I had to grind down to clear oil injector on the rear housing and the water (coolant line that goes to the throttle body). Going back to my issues before I have individually powered up the pumps right off the battery using 8 gauge wire and grounding the pumps to the chassis and the battery to boot. Also installed in line are two (one per fuel pump) 40 amp relays. After all this work and voi·là the system still falls flat on its face and looses fuel presure. Next step will be to use Moroso aluminum hard line from back of the car to the front. I will also be utilizing all the proper y's and compression fittings. Essentially I will be using regular 3/8" fuel hose for 10" off of each fuel pump. I will route them together at a high flow "Y" manifold with two 3/8" inlets and a 1/2" outlet. The the inlet will have barb fittings the outlet will go to a compression fitting. this I will also do at the fuel filter end. I will tuck all this back into the fuel line tray tied down to the chassis. I cannot think of a better solution currently. If this does not work I think like cewrx7r1 said I have a bad case of ghosts in the fuel.

HUGH

Just completed the fuel system last night and turned the key over. Only problem encountered was the hard line connection to the fuel filter got accidentally crimped and I was using a swagelok style fittings. This resulted in not being able to put on the brass ferrule over the hard-line. Thank god the hard-line package came with 25’, so I had to redo the hard-line under the car. This also included using ½” runner lines slotted and slipped and zip tied over the hard line so that no wear points would develop. Any ways the second time I was getting tired so I had a break and looked at the engine for a bit. I had placed the trouble light on top of the firewall and intake plenum area when lo and behold! Rear Housing has a port that was open to atmosphere! Dammit and I just spent all this dough on fuel lines & fittings. Promptly plugged the port and finished the fuel system (plastic conduit was a bastered to get on over the ½” pipe and factory lines, many zip ties were used). Primed the fuel system turned on the car and she ran like a trooper. There was a benefit of the fuel system was that the back pressure on the pumps was lower. Hence should experience longer life from them anyways. Now back to the dyno tuners for some tuning.