brentsz06

So my car is stock for the time being, but I plan on boost in the future. My car has the infamous fuel sending unit issue, and I've been debating on upgrading the fuel pump while I'm in there. My question is should I install a new sending unit and drop a walbro 400 in my factory setup, or put a racetronix drop in unit in the car? My only worry is that won't be enough pump to safely fuel 6-700 rwhp. But I'm not sure. Any input from anyone who has don't this please chime in. Thanks guys.

Turpid porpoise

Fitting anything larger than the drop in walboro 255 requires a bit of cutting and customizing to make it work. If you want to hit 600-700 whp in the future I would do the drop in pump, boost a pump and a meth kit(once you go F/I).

Edit: Just realized you're talking about a 2004, more options for you than those of us with early style fuel tanks.

Dave concrete

You can do a C6Z fuel pump that drops right in, and BAP if and when you do all your mods. I'm also not sure of the infamous issue you mentioned. I had never an issue and been boosted for 14 years with a simple BAP with 600 to the wheels.

Turpid porpoise

The contacts on the fuel sending units can break away leaving your fuel level gauge useless but I thought this was corrected prior to the switch to the C6 style fuel tanks.

Dave concrete

Yeah the only issue I knew of on the 04's were the crossovers which was fixed under recall/bulletin.

aaronc7

Walbro 450 fits, but you need to mod the bucket and use the standard filter sock. You lose the functionality of having a full bucket of fuel so could have fuel starvation if fuel is a little low in corners etc. Since it's a twin tank... 1/4 tanks is still half full on driver side, so maybe not as big of a deal.

I ended up getting a C6 lingenfelter pump, which is basically a ready to drop in bucket with a 450 and has everything to retain the bucket fill and all stock functionality... you definitely pay for it though.....but it's nice having a drop in solution that gives up zero vs stock.

With this pump I also put a BAP on for good measure and the pump supports those power figures easy.

The biggest drawback of this system (and stock) is the fact that fuel pressure is regulated at the tank. So I get 60 psi all the time, but at WOT high rpm it drops to around 54psi at the rail.. I think lowest I've ever seen is 52psi. It's not that the pump can't keep up, it's that it's regulating to 60psi at the tank, but due to pressure losses in the stock lines etc at these high flow levels.... ony 54ish we'll say at the fuel rail.

Which means you need to oversize the injectors a little bit to be safe since at high rpm you'll be fighting positive manifold pressure and a little fuel pressure drop. I have Deka 80lb/hr and it idles fine and duty cycle hits around 80 at 6700rpm at around 12psi... haven't dynoed, but this is a stock displacement motor with ported 243 heads, cam, bolt on etc--made 450whp SAE when NA. This constant fuel pressure, but drops a little at redline is the worst of both worlds, you soon have too much injector at idle and too little injector at high rpm WOT.

If I could go back in time I would use this same in tank pump, but would add a return line and regulator on the rail (plus you have to block off the stock regulator on the tanks). this way I could run a consistent 45psi or whatever base pressure which would actually help idle and would give me more fuel headroom at high rpm and just overall be a more consistent system for fuel tuning etc I think.

I still might do this one day.....but dropping the tanks was not very fun and I don't feel like doing it just for this at the moment. It runs fine without the front regulator, but with would be better.

If you don't want to drop the tanks, look at the external pump systems like ECS and AA offer