C5Natie

Hey guys. When I first did my vortech install the shop told me I that they upgraded to fuel pumps to a dual Walbro 340's. I never checked since I never had a problem. Now I have installed a smaller pulley, bigger 103lb injectors and e85. At only 10psi and 671rwhp with low timing, I'm losing fuel pressure past 6k rpms. It's going from about 75+ to 50psi. Looks like I'm maxing out the pumps. Will dual 400s do the trick? Aiming for 700rwhp.

When we were suspecting the fuel pumps, I took video of the gauge. As you can see, when the pull starts it starts to lose pressure. Another concern is how much the needle is shaking. Not sure if its being caused by engine vibrations or a bad/clogged fuel filter/pressure regulator. Its a 2002 so the fpr is built into the filter. Anyway to be safe I ordered a new filter since I cant even remember the last time I changed it.


LS3 with v2si.

MrH00nel2

my first suggestion is get a better mechanical fuel gauge. and then get a electronic one for inside the car.

MrH00nel2

looks like you are 42lbs. whats wrong with that

BLOWNBLUEZ06

Assuming you've got the real deal and not the Chinese knock-offs, with 12v at the pump, at 70psi, two GSS340's should flow 175lph with two running 350.
With 13.5v at the pump, 220/440lph.

Even Aeromotive pumps are becoming more and more prevalent in the Chinese knock-off market. Retailers and shop owners often don't know which they got.

Two Walbro 485's:
12v input at 70psi is 300/600lph
13.5v input @70psi is ~350/700lph

That's plenty more flow to make it happen as late as your pressure is dropping.

C5Natie

I picked up 2 Walbro 450's yesterday. Made sure they're stamped made in the USA. I never saw with my own eyes what pumps the shop installed in there but I'll find out Iin a couple days.

C5Natie

They're on my list. This is a temporary gauge to check pressure while on the dyno.

C5Natie

We didn't get to redline and the Iinjectors were over 100% duty cycle. Why chance it

BLOWNBLUEZ06

They will not fit next to each other. Not even if you open the hole all the way to the studs in the tank. You have to install one and then the other afterwards or do something custom, like I ended up doing. Make sure you use the proper submersible hose or Teflon. Something compatible with E85. Gates says their FKM hose is compatible and submersible. It's 29.00/foot

I'm not sure how close the counterfeits come to the real deal as far as the stamps are concerned. Might want to do some research on it.
http://www.fuel-pumps.net/walbro-forgeries.html

Chinese are apparently counterfeiting all kinds of pumps. Bosch, Walbro, AEM etc AND they can even say WALBRO on them. I still haven't discovered how to tell the difference.

C5Natie

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.

C5Natie

Yeah we had to cut open the bottom of the bucket, which had already had been modified. First I stuck the pumps in one at a time, then I stuck the bucket in and pulled the pumps into the bucket. I fed the wiring through, intalled the hat and bam, they were in. I used the hose Walbro supplied themselves with the pumps.

PEETYZ

Might want to double check to be sure that hose is submersible. Had a buddy install a dual pump set up and had all kinds of issues a few months down the road when the incorrect hose deteriorated and pieces found there way into filters and clogged them etc. Pretty sure it burnt up one of the pumps as well.

C5Natie

The kit is specific for e85 use. You can see the part number on the install kits, ends with 85.

MrH00nel2

I had 2 walbro 255 side by side in another car of mine and on a hot day with low fuel one would overheat and quit, then come back on when it cooled off. Just a little precaution for you.

good luck hope it works out

C5Natie

Thanks. So far so good but we'll see in the dyno. Yeah, especially with high performance fuel pumps i try not to go lower then a 1/4 tank. Thats usually when i fill up.

PEETYZ

ok good

BLOWNBLUEZ06

Even with the hose that came with my Walbro pump kits, I decided to buy the real deal. There were no markings on the hose and I decided it's not worth taking for granted. Ordered the Gates FKM submersible, E85 compatible hose and will throw the other two pieces away before it's all said and done. I'm not aware of any other manufacturers of FKM hose, so if it doesn't say Gates or SAE30R10 on it, I would toss it.
I don't have time to look back up at this thread, but I'm wondering if you're running both pumps full time. They heat up the gas a lot more than a 255 does, so running 2 would worry me that they're going to cavitate.

RonSSNova

I'm just curious why you wouldn't complete the return fuel system before going to the dyno?
Esp since you are going to have to re- tune after the change?

Ron

MVP'S ZO6

Racetronix sells factory style ribbed hose and clamps.

That submersible hose from gates that blown blue is talking about is pretty pricy for hose but

Not all fuel line is created equal ask me how I know. Lol.