Topic: Walbro Inline Fuel Pumps

[bluedevil]

To MainOne,MyBigToy or KYBob:

Ok....so is this necessary when using a blower?  Will it help to shoot fuel better into the injectors? Is it a waste of money?  http://www.inlinefuelpumps.com/

My AV is a 2004 Z71 5.3

[MyBigToy]

The Magnacharger kit for 99-02 model years came with a Walbro in-line booster pump. I know Bob's got one on his truck also. The Magnacharger returnless fuel system supposedly is able to keep up without a booster pump as long as you don't make a lot of additional modifications.  You'd have to at least monitor your fuel trims to determine if you need additional fueling.

[bluedevil]

I figured if i add a smaller pulley i should get this but im not sure if i have to replace the injectors to 60# or not.  I currently have 42#'s.

[MyBigToy]

I think Bob's still got the 42# injectors and he's pushing quite a bit more boost than either one of us. Fla had his duty cycle maxed out and I believe I remember he switched to 60# injectors; he was pushing a bunch more boost & hp than either of us.

I'm changing to a 3.2" pulley next week (it was supposed to be this week but the shop was too busy) and don't plan on additional fueling changes. This is supposed to add a couple of pounds of boost and 20 hp. I still haven't ordered the 2600 stall converter yet.

[bluedevil]

I think Bob's still got the 42# injectors and he's pushing quite a bit more boost than either one of us. Fla had his duty cycle maxed out and I believe I remember he switched to 60# injectors; he was pushing a bunch more boost & hp than either of us.

I'm changing to a 3.2" pulley next week (it was supposed to be this week but the shop was too busy) and don't plan on additional fueling changes. This is supposed to add a couple of pounds of boost and 20 hp. I still haven't ordered the 2600 stall converter yet.

I thought i saw Bobs signature and it shows 42# inj but i dont know if its an old siggy.

Yeah...im planning on purchasing the 3.12 pulley as well and maybe with more info,i'll get the walbro 255 as well with whatever plumbing necessary.

dammit....i want the intercooler but its $1.900 .......yikes!

[MyBigToy]

dammit....i want the intercooler but its $1.900 .......yikes!

You could always do meth injection instead.

[Richie_Rich]

Someone posted this on my Starquestclub yesterday.
We've had a couple guys have their Walbro's fail after a short period of time.

http://www.fuel-pumps.net/walbro-forgeries.html

Make sure to buy from a reputable shop.

[KY_BOB]

You can't run a booster pump on a returnless system as it has no way to bleed off the excess pressure.

My '02 kit didn't come with replacement injectors.  It relied on a FMU and booster pump to supply the extra fuel.  With a returnless system the only way to increase the fueling capacity it to run larger injectors.

That said, even with the booster pump and FMU, I exceeded the capacity of my stock injectors and swapped to 42# injectors.  I'll be glad to get into this more next week, I'm off today and heading to a bike rally for the weekend.

[KY_BOB]

OK, I have a couple of minutes while waiting on a female. 


I think stock injectors are 28#.  Injectors are rated at a certain fuel pressure.  If the pressure is increased, they will flow more.  The FMU that came with my kit increases fuel pressure as boost pressure goes up.  After going to the 3.12" pulley, I was seeing my 100psi fuel pressure gauge peg and I was still over 100% duty cycle.  I then bought 42# injectors that came with Flabouy's kit and went back to near stock fuel pressure. 

Blue, your kit should have came with the same 42# injectors that I have.  You really should log the injector duty cycle to see how close you are to maxing them out now.  A 3.12" pulley may be over their limit.  A booster pump isn't an option on your '04's returnless system. 

The newer trucks with the returnless system are regulated in the tank and run at a constant fuel pressure at all times.  I'm thinking that's 52 psi.  The older systems have a vacuum referenced regulator which adjusts the fuel pressure based on the engine load.  They will vary the fuel pressure from 50 to 58 psi base on the amount of vacuum being pulled.  The FMU on my system is basically a restriction on the return line.  As boost goes up, it restricts the amount of fuel being returned to the tank thus increasing the pressure at the injectors. 

After going to the 42# injectors, I changed the disk in the FMU to cut back on the amount of increase in pressure.  I'm maxing at about 65 psi right now.  The reason that I can get by with 42# injectors at the same boost as Flabouy is that his is at the stock 52 psi and mine can climb to 65 psi.  If I max them out, I can add a little more pressure if needed.

Make since?