Fuel pressure gauge went backwards

[Son_of_Norway]

Hello, the coach is stalling and dying on acceleration and I'm trying to make a definite diagnosis. I installed a fuel pressure gauge along the frame rail just downstream of the fuel tank so I can tell if the in-tank fuel pump is working. When I started the coach the needle went backwards and pegged at the opposite side. I'm thinking this means the in-tank fuel pump is not working and gas is being drawn forward by the mechanical pump. Is this correct? I'd like to be sure before I start trying to drop the tank. Thanks to all for your help.

[1995brave]

I see you have a Chevy chassis with 454. Is it throttle body or carb? On the passenger side just in front of the rear axle should be a fuel filter. You can always connect your pressure gauge before or after the filter to check fuel pump pressure.

[schlep1967]

Is it possible you attached your pressure gauge to a return line to the tank? Look for another line.

[fulltimin]

If this is the rig in your sig, it may or may not have a fuel pump in the tank. A lot of rigs built in that time frame had none in the tank.

However, it may depend on whether or not this has a carb or is fuel injected.

If it has a carb, best place to put the gauge is between the engine mounted fuel pump and the carb.

If it's fuel injection, then usually there was a tank mounted pump, with no pump mounted on the engine.

[Nick-B]

Might help if we knew what chassis/engine you have.