I also agree not necessary to run both pumps all the time my second pump is also controlled by a hobbs switch, you can change back and forth to what pump is your primary to keep run time equal on both pumps for long life of each. The 43-45 base fuel pressure seems to be a very low starting point as most injectors for our aplications are rated on a 58 base psi. If your goal is 700 that should be easily accomplished with twin 255 and 103 lb injectors. I'm at 957 18 psi and 96 lb injectors on 94 pump gas

 

There is nothing wrong with running both pumps. This subject has been debated to death. I ran two 255's for a year when I was N/A 400ish and I never had any fuel heating or pump failures. I now run 044's. Almost everyone I know that is pushing 700 or above (a lot of people) run dual pumps all time. Get yourself a decent sized feed/return and let those pumps go to work.

 

I agree with this. I have both 255 pumps on at all times in my car.

 

Thanks for the advice guys. I always thought as long as fuel is cooling the pumps it shouldn't be a problem, especially with e85 seeing how it runs cooler. I got the 2 walbro 400's today so I'm gonna start piecing this stuff together. I'll post the results as well as if I find out what went wrong. I have a feeling one pump went out.

 

Good luck!

 

Some info missing here.

You have uprated pumps ? But still a dead end setup as far as fuel supply goes ?

What size line are you using from pumps to engine ?

As others say, pumps should be ok, wiring /voltage should be confirmed is good, but your current problem could simply be lack of supply pipe diameter to the rails which is even more vital to be a good size when running no return setup.

Running 2 pumps is fine, I've had 2x044's running in parallel for nearly 10 years with zero problems.

 

Does this, crude, drawing check out on how to route a return style system on a C5? Thanks.

 

The lines are stock c5 lines so I'm sure they need to be upgraded

 

No.

The FPR is ideally the last item before returning fuel to the tank.

ie it would be mounted after all the injectors.

Ideally fuel will flow from the pump, then through both rails in parallel, and then into the regulator

 

better?

 

You've plumbed the fuel rails in series there. yes it is better, but ideally you'd run the rails in parallel.

ie split with a tee or Y before the rails, and the rejoin to a single line after the rails.

or most regulators have 2 inlet ports, you could use one for each rail. Entirely up to you whichever plumbs up easiest.

But if the rails are decent diameter, nothing much wrong with how you have it drawn above. I'd still prefer parallel

 

Gotcha. Thanks for the tips.

 

New Walbro 450's ready to go in


Pulled out the old setup. There were no markings or part numbers on the pumps. They look just like Aeromotive 340's and i dont know if the marking got "washed" off by fuel. I'll post pics of the pumps tomorrow.


Squeezed the two Walbros in the bucket. The bottom already had an opening so that the strainers of the fuel pumps could stick out. I had to basically just had to open up the bottom of the bucket to fit the 450's.






Needless to say, we were able to squeeze them in and everything checked out and the car runs just fine. Next step will be to get back on the dyno, keep an eye on the fuel pressure and finalize the tune. Then I can start on that fuel return setup.

 

Did you modify the bucket with a Hotwire? If you run that much amperage through the stock bucket terminals/wiring it will potentially and eventually burn up. I don't think melting terminals and fuel go well together.

 

Those Walbros draw insane amounts of current.

All wiring and connectors will need to be substantial.

 

Already had a hotwire kit. It's a very heavy gauge wire with a 50 amp fuse setup with a relay as well. We double checked all the wiring as well as current draws and voltage. I had already upgrading the entire fuel system wiring and harness before.

 

Yes they do. One of my bulkhead connectors on my sending unit on my c4 got burnt up from the current going through it over just a few street miles. I've since switched to a dual pin setup.

The prior setup lasted for a long time with dual walbro 255's so I think that these have some serious draw.

Maybe it was an old part failing or maybe it was increased current draw. Who knows....

 

I got 10 guage wire feeding the pumps, each has 12ga I believe. Feed from alt, big 50amp fuse and relay. Soldered and heat shrinked all connections. Only stock wires are the command signals from the ecu coming from the engine bay fuse box. That triggers the relay to turn the pumps on.

 

 

Nice job! Can't wait to upgrade mine to twin 450's.