Depressurize the fuel system?

[redhat]

What is the quickest and easiest way to depressurize the fuel system - in preps for fuel filter replacement?

Thanks.

 

[JDraper]

With the ignition off, either pump the gas pedal a couple of times (you'll have to wait a while before you starta it again to let the gas clear afterwards) or depress the schrader valve on the fuel rails (it's the same type of valve as you have on your tires). The second is the recommended way.

 

[redhat]

JDraper - thanks for the help.

 

[JoeC5]

Do you have to depressurize the fuel system before you change fuel filters?? I usually just get underneath the truck and change it right out with no problems at all.

 

[CHH777]

I just trip the rollover safety shutoff switch and run the engine till it dies...

 

[Robert]

Originally posted by JDraper
With the ignition off, either pump the gas pedal a couple of times (you'll have to wait a while before you starta it again to let the gas clear afterwards) or depress the schrader valve on the fuel rails (it's the same type of valve as you have on your tires). The second is the recommended way.

On a fuel injected engine, pumping the gas pedal shouldn't work. As long as the ignition is off, the fuel injectors aren't injecting any fuel. The only thing the pedal does is open up the throttle body butterfly to allow more air in. The computer then injects the fuel in response to the opening of the throttle body.

I don't know about the second suggestion either. It wasn't in the Service Manual. What was in the service manual was installing a vacuum pump to the valve and using it to bleed off the pressure. An alternate method was to start the vehicle, and pull the connector off the top of the fuel shut-off switch and run it until it dies (a few minutes). That is the method I used when replacing my fuel filter on my '97 and it worked very easily.

 

[Robert]

Originally posted by redhat
What is the quickest and easiest way to depressurize the fuel system - in preps for fuel filter replacement?

Thanks.

Another quick suggestion is to make sure you have the quick disconnect tool before starting the replacement. It sucks to fight and pull on the lines, get one off and find out about the quick disconnects. You will then be looking for another vehicle to drive up to the auto parts store for the $5 tool.

 

[JoeC5]

Yeah, but do you have to depressurize the system?

 

[JDraper]

Brain Fart on suggestion #1. To much time with Quadrajets and 4150's!!! As for the second, that's what my Haynes manual suggested for pressure relief. Tripping the cutoff switch and running it till it dies (suggested above) does the trick too.


You should depressurize the system first so you don't spray fuel all over the place. The system pressure runs 35-45 psi (from memory, I don't have the manual handy). If you pop the filter connectors loose at pressure, you'll have fuel everywhere.