What is the normal fuel pressure for a stock lt1 in a 95 z28. Also when I changed the fuel filter there is another "filter, pump" looking thing that is on the fuel line right before the filter between the filter and the tank. The thing looks like a filter but its covered in a foam-like coating and has wires running to it. Anyone know what the heck it could be. Thanks

 

Fuel pressure for LT1 cars:

-Turn key to "on" wait for pump to stop priming. Pressure should be at least 40psi. Watch how fast it drops after the pump shuts off. Should not drop quickly

-Start engine, pull vacuum compensation line off fuel pressure regulator (FPR), covering end of vacuum line to prevent a vacuum leak. Pressure should be 43.5psi. GM accepts anything between 41-47psi as being within spec. Reattach the vacuum line to the FPR. Pressure should drop proportional to intake manifold vacuum. A 6psi to 8psi drop from the "no vacuum" pressure would be normal with a stock cam. Less drop with a more aggressive cam.

-Tape gauge to windshield. Take it out on the road. Pressure should vary with changing throttle position, due to changes in intake manifold vacuum. Opening throttle causes the pressure to rise, closed throttle decel will cause it to drop. At WOT/5,000 RPM the pressure should be very close to the "no vacuum" pressure you recorded, and in no case should it drop below 40psi.

Does your foam covered object in the fuel line between the fuel tank and the stock fuel filter look something like this (part with 2 clamps holding it to the floorpan to the left of the differential pumpkin, partially hidden by sway bar):

http://www.injuneer.com/images/photo.../DCP03551a.jpg

That was the location used for the booster fuel pump used in the NOS 5176 dry nitrous kit for the LT1. They were sometimes housed in a foam cover to reduce the noise.

 

thanks for the fuel pressure info. Its hard to tell if its the same. I am going to put it on a lift tomorrow to get a better look at it. Thanks again.

 

The foam covered thing must be a helper pump. It was making a weird noise today, so I disconnected it. It didn't seem to make a difference, I am thinking about just removing it.

 

Not good to leave it not running, if it's in series with the in-tank pump. Its a huge flow obstruction, making the in-tank pump work harder, and possibly preventing it from flowing adequate fuel when the engine is making max HP. Run it or remove it.

 

Thanks for the info. I will remove it as soon as possible. It should be the same as removing the filter, I mean the pressure in the line. I shouldn't have to do anything special to remove it, I hope.