Alrighty, I have a 96 that I'm trying to test the fuel pressure on. I've tried 3 different testers and the needle doesn't move at all. I screw the hose onto the shrader valve on the back of the intake manifold, get a little bit of gas to leak out on my hand before it snugs down and then I turn the key on. Nothing at all happens to the gauge.... What now? Am I doing it wrong?

 

Does your car start at all? Can you hear the pump running?

 

Before you start, maybe you can take the core out of the schrader valve. Put it back in when you are through taking measurements.

 

Yeah, the car starts, takes a good 4 seconds or so but fires right up and runs good. I can hear the Pump running back there as well.

 

Would removing the core cause it to start spewing fuel everywhere?

 

Only if the fuel pump is running. Turn the key off. Before you remove the core, hold a rag over the end of the valve and depress the core to relieve the pressure. The fuel pressure gauge hose should have a pin in it to depress the core valve. If it doesn't, remove the core as suggested.

 

Some of those fuel pressure test gauges that have the pin in them don't depress the schrader valve far enough, so they don't work as they are supposed to and you can't get a reading.

 

Thanx for the replys. I finally got the gage to read by removing the core. It idles at 38psi. However when I turn the key on ( engine not running) the gage goes up to about 30 psi and then quickly returns down to zero. Is it supposed to remain pressurized or is this normal?

 

When it primes for 2 seconds, should go to 40psi, and drop off slowy when the pump shuts down, not rapidly. If it goes to "0" its a problem with the check valve in the fuel pump, a faulty fuel pressure regulator, leaking injector(s), or fuel line leaks, including the hoses in the tank.

When it's idling, pull the vacuum compensation line off the fuel pressure regulator, holding your finger over the end of the hose to prvent a vacuum leak. Pressure should be 43.5psi, with anything in the range of 41 - 47psi acceptable. When you reattach the vacuum line, the pressure should drop proportional to intake manifold vacuum. You might see an 8psi drop with a stock cam, smaller drop with a more aggressive cam.

While you have the vacuum line off the FPR, check for wet fuel - that would point to one possible source of the rapid loss of pressure when the pump shuts down.