Will this work to relieve fuel pressure?

[JohnGunn]

I have a new fuel filter that I want to install on my "new" 1994 Aspire.

Not wanting to remove the back seat and tear into the carpet under it on my "new" car to get to the fuel pump power connector, I looked at the fuel system to see if I could find a less intrusive procedure. This is what I am considering.

The fuel pressure regulator has a valve in it to send fuel back to the tank when the pressure gets too high. There is a spring in the regulator which holds that valve shut until the pressure gets high enough to over come it and open the valve.

But there is also a vacuum hose connected to the regulator which opens the valve when the engine is idling and the vacuum is high. That serves to reduce the pressure when the engine idles and doesn't require much fuel.

My thought is to attach my vacuum pump to that vacuum hose and create a vacuum to open the valve with the engine off and the fuel pump not running. I would expect this to relieve the fuel system pressure by venting the pressurized gas back to the tank.

Questions:
1. Will this work?
2. Is there any way I can tell if it worked before disconnecting the old filter?

John Gunn
Coronado, CA

[doylerl]

Are you just wanting to relieve pressure or put in a filter? I am kinda confused as to what a new filter would do to fuel preasure...? If the filter inside the tank is clogged, an external filter isn't going to help anything.

[JohnGunn]

The filter I'm replacing is the inline filter located in the engine compartment. The reason for relieving the pressure is to prevent fuel from spraying out when the old filter is disconnected.

John Gunn
Coronado, CA

[Pu241]

I should think engaging the fuel cut off switch in the truck area, then trying to start it should reduce fuel pressure in the rail very effectively.

[501Dezz19]

When I replaced my fuel filter I just used 2 pairs of vice-grips and clamped the fuel line,top and bottem of the fuel filter got a new fuel filter pluged the lines in and released the vice-grips and that was that...

[speedoholic]

Just putting a rag around the hose and pull it off the filter. That's what I do. But I have also caught my Festiva on fire working on the fuel system:violent3:

[Nerd Racing]

I've never had fuel spraying in the face before, but yes if you start it with the inertia switch tripped in the back (or trip it while running) that will drain the lines.

[scitzz]

Just putting a rag around the hose and pull it off the filter. That's what I do. But I have also caught my Festiva on fire working on the fuel system:violent3:

Whelp. That about wraps THAT up

[Roboskittle]

I have never caught a festiva or aspire on fire working on the fuel system. Just pop the gas cap off and pull the lines off. It doesnt spray that much out. Just take your time with it and it will go well. Hell I even smoke when Im changing filters. I never understood the precautions people take for fuel filter changes.

[skeeters_keeper]

I've changed dozens of fuel filters and never done more than pop the gas cap to relieve and pressure built up inside the tank.

A few weeks ago I pulled the lines off a truck and it had a TON of fuel pressure still in the lines... sprayed out almost a quart of gas, I'm guessing. Right onto the super hot catalytic converter... fuel was sizzling off that thing like crazy!! It scared the crap out of me... i took off sprinting for the fire extinguisher. Amazingly it never lit.
Then the other day while I was driving my festy I started to smell gas. One of the o-rings around an injector was leaking... right above the cat. Once again, no fire, I was quite surprised.

All that to say - take the necessary precautions, and just b/c it didn't happen to others doesn't mean it won't happen to you, but really just pull the lines off... once they are off the pressure will be relieved :p

[htchbck]

pop the inertia switch while the car is running. Works everytime. And just to be on the safe side, wait till the car and cat are both cold to pull the lines

[Pu241]

Hell I even smoke when Im changing filters. I never understood the precautions people take for fuel filter changes.

So I guess we'll be hearing about you one day on the news!
Guess you don't understand why they have no smoking signs at gas stations either?

[Roboskittle]

Ever throw a lit cigarette in a barrel that you just poured gas all over to try and light it??? Nothing happens. A lot of you have watched too many movies where the bad guy or good guy throws a lit cigarette into a puddle of gas and off it goes. That doesnt happen in real life. Gas needs temps of 550 F plus to be able to ignite. Cigarettes really dont have that temperature potential unless you can suck on it long enough to get it that hot. They have the no smoking signs for the same reasons they have the no cell phone signs. It is possible but the conditions have to be just right. Lighting a cigarette around open fuel lines is something I would never do though.

[Pu241]

Roboskittle, this for you.
BTW, just because it hasn't happened to you yet, doesn't mean it wont!
I just want to give someone without your "vast experience" a chance to live long enough to know better!

http://www.physlink.com/education/askexperts/ae1.cfm

[Pu241]

pop the inertia switch while the car is running. Works everytime. And just to be on the safe side, wait till the car and cat are both cold to pull the lines

Like this idea better, than trying to start it after hitting the inertia switch!