Maxed out fuel system


Apr 9, 2008
I've been trying to figure what is maxed out in my fuel system. I'm running a new walbro 340 and sender from racetronix, hot wire, 60 lb injectors and alky control kit set to 8 on a single nozzle. I'm having problems maintaining an 11.0 AFR at higher rpm's. It seems that after about 21 lbs of boost it starts to lean out fast and I have to let off. I've added a bunch of fuel to the chip and it made no difference and I also wired in a kenne bell boost a pump my buddy had and it made no difference. I'm thinking it's my stock feed line, any other ideas?
you need to see wot fuel pressure to see where everything is at,also where is the base rail pressure?
there is plenty of fuel to be had with a walboro and single nozzle.verify pressure and if you have it raise baseline pressure up and put some voltage to the pump with the volt booster.
A single Walbro should be fine with 60# injectors up to around 90% duty cycle. Beyond that, you may need a volt booster. I'm running the Kenne-Bell boost-a-pump. Very easy to install and it boosts the voltage to the pump only when the engine is producing boost.

the fact that you've tried the Kenne-Bell makes me wonder, did you hook it up correctly? did you verify the voltage or at least jump a wire on the Hobb's switch to force it to high-volts so that you can 'hear' the difference?
Don't just THROW parts at it !!! FIND the problem.:rolleyes: We have your set up but ran it with a 67 turbo.
I have 17.2 volts at the pump when under boost so I know the boost a pump is working. The alky pump is a year old and the motor bogs down when i prime the system and the led switches to green around 5-10 lbs of boost so it seems fine. The weather has been crappy here so I can't verify the fuel pressure under WOT. The feed line is not original and it does make one sharp bend under the car before it goes into the engine bay. Hopefully the weather will clear up soon!
You can make a DIY line that goes from the bottom of the FP regulator (return line) and make up a hose leading into a bucket.... then cut the pump on and adjust the FP up to the static FP (43-45 psi most likely) + the boost you want to run.... so this would be setting the FP (for this test) to 63-65 psi if you were targeting 20 psi boost...... then you see how long it takes to flow 1 gal of fuel into the bucket (most car wash buckets have marks on the inside with gallons and quarts visible.

In a nutshell, you are figuring out if your fuel system will flow enough fuel to support the HP.

If you have some issue like a split hose inside the tank or something funny going on with the pump mount or fuel sock.... or anything really between the fuel pump sock and the return side of the regulator, you will see it.

This is probably more safe ayway than staring at a FP gauge at WOT in most instances.