Last year my 14 year old bosch inline pump started dropping fuel pressure at full boost in the upper rpm's so I figured I needed a better pump. I purchased an A1000 and hooked it up per the instructions for the 94 Lt1 kit they make. After installing it I had to change my pressure regulator because it couldn't lower the pressure enough. I installed the aeromotive APR on the fuel rail. I could adjust the pressure down to 45 psi and the car ran great. I purchased the pump controller then to keep the pump from burning out with street use. After installing the controller the car ran fine but would die when coming to stop signs with all the lights on the controller blinking. In the middle of trying to adjust the controller's RPM settings/ thresholds, the pump died only putting out 10psi or less, I was able to idle the car home from the gas station. The pump was a month old. A call to aeromotive yielded the pump was damaged, but not from the controller but having too small a feed line to the pump. Aeromotive rebuilt the pump for free and instructed me to install -10AN line between the tank and the pump via a bulkhead on the top of the tank. A few weeks later the car was back together and never ran right again. It has sat all winter in the garage waiting for warmer weather.

Present Day:
The car shows lean on both banks of the widebands intermittingly, from what seems like a slight miss to completely undriveable. Fuel Pressure is constant at 45psi and increasing the pressure on the regulator to 55 makes no improvement or change in the cars lean situation. Also changing the injector size from 72 to 60 also showed no change in the cars rich/lean readings? Over the winter I removed both headers and installed new aluminum gaskets and donuts to the y pipe in case of an exhaust leak affecting the widebands. New wires and plugs were installed. The car shows no codes. Unplugging the MAF makes no change in improving the situation. All 8 coils are firing.

This all happened immediately after installing the rebuilt pump and adding a new pickup in the tank. I removed the pickup thinking maybe air was sucking into the fuel line thru the AN connection and aerating the gas. The pickup is a braided 10an hose fitted to the bottom of the bulkhead in the tank. Reinstalling it made no improvement. I then installed a clear piece of fuel line on the return line going into the tank. When the pump runs you can see constant air moving thru the tube with the gas. I tried bypassing the tank, fitting an 8AN line onto the AN fitting on top of the tank and running the fuel line into a 5 gallon gas container filled. The air is still circulating with the fuel. There are no leaks in the external fuel system. Could the pump be bringing the air into the system, is the air normal?

Here is a video of the fuel line:

http://wayneg.smugmug.com/Other/Cama...147573_g7pd5cX



Any help or insight is greatly appreciated.

 

Are you sure it's air, and not fuel vapor bubbles?

 

I'm not sure of anything. I never looked at fuel flow thru a fuel line before. I also didin't mention that the widebands were swapped out with no change, the cars computer gets dumbed down output from the FAST controller, the fuel injectors were sent back to versafueler and cleaned / flow mached and tested good after the pump was repaired. I'm gonna call aeromotive today to see what he has to say.

 

Well I talked to aeromotive today and all I can say is there tech department is great. He actually wanted to solve my problem and not just blow me off. After discussing my setup and the changes he said that the right angle bulkhead I used was probably an issue causing cavitation. So I bought a straight bulkhead tonight and swapped it in and connected a smooth radius 90 degree AN fitting on to it. I started the car up and immediately noticed that the widebands weren't fluttering anymore towards lean. I took the car for a 10 minute drive and it seems that the problem is 95% gone. The other 5% I think I'm gonna have to mod the fuel rails for parallel feed and do the return from the crossover pipe like injuneers car. I'm also gonna have to figure out a new way to connect to the tank because the straight bulkhead and smooth 90 are sticking up 3 inches above my access panel, at least I know what the problem is now

Thanks Injuneer you were right it was a vapor/cavitation problem not air.

 

Yep... poor suction plumbing.

I haven't had any problems with this approach though, -10AN:

http://www.injuneer.com/images/photo.../DCP03576a.jpg

But that's only for one of the two 205 LPH pumps. The other one is in the tank. I think the A1000 flows about 375 LPH, and the higher the flow, the more likely the problem.