Fuel pressure relief?

legacy92ej22t · Post by **legacy92ej22t** » Mon Oct 13, 2003 3:37 pm

I'm changing my fuel filter today (way past do

) Do I really have to relieve the pressure like my Haynes manual says? Take out the back seat, unhook fuel pump blah blah blah? Seems like this was discussed before, I searched but came up empty.

entirelyturbo · Post by **entirelyturbo** » Mon Oct 13, 2003 3:49 pm

I relieve it. It's really simple. Have the engine running and pull the fuel pump connector, the engine will die in about 2 seconds. The pressure is now relieved. Don't forget to hook the connector back up after you're done changing the filter.

Or, you can let the car sit overnight and pressure will be pretty low in the morning...

THAWA · Post by **THAWA** » Mon Oct 13, 2003 3:53 pm

haynes lied to your face! but don't worry they lied to me too. You don't have to take out the back seat, just lift up the carpet in the trunk, all the way up to the back seats,and you'll see your fuel pumps, or pump. I know on 4wd sedans they are close to the back of the seat and theres an oval one on the passanger side and a round one on the driver side.

vrg3 · Post by **vrg3** » Mon Oct 13, 2003 4:44 pm

Yeah, that lousy Haynes manual!

Like these other guys have said, you should relieve pressure. Even without pressurized fuel lines enough fuel spurts out when you remove the filter; you don't want even more coming out.

There's only one pump; it's under the oval cover on the passenger side. The cover's held in by 4 philips head screws and I'll second that it is easily accessed by lifting the carpet. I accesed it by just removing that plate attached to the back of the folding seat (held in with a few philips head screws) and the folding the carpet back a little.

The way I prefer to relieve pressure is to disconnect the pump and then crank the engine for several seconds. If it starts, let it run until it dies and then crank again for several seconds. That way the injectors will dump as much fuel as possible out of the line. If you just unplug the pump and let the engine die there will still be some fuel in the lines, just not enough to keep the engine running.

legacy92ej22t · Post by **legacy92ej22t** » Mon Oct 13, 2003 6:50 pm

Thanks guys! Unhooking the fuel pump was a snap. I just folded my seat down and pulled the carpet back. The hardest part of the whole job was getting the gas lines off the old fuel filter. What a bitch! Thanks again.

petridish38 · Post by **petridish38** » Mon Oct 13, 2003 6:55 pm

if you have the fold down seats like me you are lucky.
i replaced the pump on my friend's 91 L which doesnt have the fold down seats and it was hard to get the phillips screws out. that makes things a bit harder.

Even without fold down seats, it can still be done without taking the back seat out. I did it!

THAWA · Post by **THAWA** » Mon Oct 13, 2003 6:56 pm

Tell me about it, took me a good 5 mins to get the out tube off. vrg3 whats the connector under the round plate for?

Tleg93 · Post by **Tleg93** » Mon Oct 13, 2003 7:19 pm

I didn't relieve any pressure I just clamped the fuel line to keep gas from leaking all over. It worked fine and I didn't have any troubles at all afterwards. I used a bobby-pin to loosen the hose. Does not relieving pressure affect the pump somehow? I just figured it was as simple as taking the old filter out and putting a new filter in. It doesn't seem like a very technical operation.

mTk · Post by **mTk** » Mon Oct 13, 2003 8:37 pm

I replaced mine w/o relieving pressure, i don't think it is harmful to the system. I just made sure to keep a rag wrapped around the fuel line to soak up any gas that would spill.

MK

georryan · Post by **georryan** » Tue Oct 14, 2003 12:33 am

So you guys were changing the filter that is in the tank itself, not the one in the engine bay?

Wonder if I should be changing that one sometime soon.

THAWA · Post by **THAWA** » Tue Oct 14, 2003 12:46 am

I think he was talking about the engine one

mTk · Post by **mTk** » Tue Oct 14, 2003 2:16 am

Yeah, the filter in the engine bay.

MK

georryan · Post by **georryan** » Tue Oct 14, 2003 2:23 am

Why did you pull the wires in the back of the car then? It doesn't hurt I guess, but I've never done that.

THAWA · Post by **THAWA** » Tue Oct 14, 2003 2:28 am

they are signal wires to get the fuel pump working and all that stuff.

vrg3 · Post by **vrg3** » Tue Oct 14, 2003 9:09 am

THAWA - The connector under the driver side plate? I don't know. Perhaps the fuel level sender? I can check later when I have access to my manuals.

Padishar Creel - I think the only reason to relieve pressure is to avoid spraying fuel everywhere. It's a fire hazard, and just unpleasant. But I don't think it hurts the pump or anything.

georryan - You pull those wires and crank the engine so that the injectors dump all the fuel that's in the lines into the cylinders. That way, the lines will be close to empty instead of bursting with fuel like they normally are.

Tleg93 · Post by **Tleg93** » Tue Oct 14, 2003 11:55 am

I see, thanks. It doesn't hurt to be sure. I've done things in the past on the fly only to find out that the step I skipped was important.

legacy92ej22t · Post by **legacy92ej22t** » Wed Oct 15, 2003 4:22 am

Wow, the new fuel filter really seemed to smooth out my idle. Can barely tell it's running now.

mTk · Post by **mTk** » Wed Oct 15, 2003 4:23 am

Good to hear!

MK

123c · Post by **123c** » Wed Oct 15, 2003 6:35 am

It looks like it's about time for me to change my fuel filter also. Does anyone know the size of the rubber fuel lines? I am wanting to replace them with the German Cloth Braided Fuel Line, I like this stuff because it will show when there is a fuel leak...

Tleg93 · Post by **Tleg93** » Wed Oct 15, 2003 2:29 pm

Right on Matt, I wish it would have had that good an effect on my beast. As it is I have to whip it regularly to get it to purr. She's tempermental sometimes.

georryan · Post by **georryan** » Thu Oct 16, 2003 12:06 am

vrg3: ah I gotcha. I always thought to just pull the fuse in the fuse box. Disconnecting the electrical wires would do the same thing though. That makes sense. hahaha, I thought they were pulling the fuel lines themselves from inside that cap in the trunk.

vrg3 · Post by **vrg3** » Thu Oct 16, 2003 12:13 am

Pulling the fuse won't really do it, because that also disables the ECU. So you'll crank the engine but not inject any fuel. What you want is for the ECU to pulse the injectors but without the fuel pump running. The only way to do that by just unplugging something is to unplug the fuel pump relay or the pump itself.

Post by **Legacy777** » Thu Oct 16, 2003 1:42 am

You know what......I had my ECU fuse pulled....forgot to put it back in, and started the car......car started and ran fine.......I was pretty confused.......would've thought it wouldn't run.

vrg3 · Post by **vrg3** » Thu Oct 16, 2003 2:11 am

Are you talking about fuse 14?

That fuse only supplies backup power to the ECU. While the car is running, the ECU is powered from SBF-2 through the ignition relay.

Post by **Legacy777** » Thu Oct 16, 2003 2:51 am

that would be why it worked

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