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View Full Version : Is there pressure in fuel lines after shut down?



Frank818
01-19-2017, 07:43 AM
I bet Bob will answer this question. :)


I need to drain my tank (not fully but at least under the filler hole) to swap t-bolts at the bottom hose and filler neck tube junction and I know it will leak from there once I remove the t-bolt, hence the draining first.
Besides, the gas is 1yo and I prefer to have fresh gas when I start the engine again this Spring.

If I unplug the feed line's connector (white) on the pump in order to plug another line going to my portable gas container, will the fuel splash off until the pressure is relieved or there is no pressure and nothing will splash?
If nothing splashes, will fuel pour out or the line is empty? Last time I ran the engine was on Aug-5th.

I cannot remove the line at the FPR near my fuel rail, the way it's installed in that location on my VR6 I need to cut the line and re-create a new line (which means disconnecting from the fuel pump anyway). The design of my FPR is really bad, the hoses are too tight on the barb fittings (so they twist if I unscrew the fitting) and the location gives me no good access for tools and hands to have a good grip. Need to cut. Don't want to cut.


tnx

Hindsight
01-19-2017, 09:29 AM
Fuel pumps have a check valve in them that holds pressure in the line. Over time, the pressure can bleed past the check valve, depending on the valve's age and design. If it's been sitting for a long time (months), chances are that there is very little pressure in the lines. This is not an "active" check valve though. Meaning unplugging the electrical connector won't depressurize the lines. It's just always there in place... mechanical.

STiPWRD
01-19-2017, 09:47 AM
^Exactly, if you haven't run the pump for a while there will be very little (if any) pressure built up. Just put a rag below the fitting when you unplug the hose to catch any fuel drip.

Frank818
01-19-2017, 10:21 AM
Ok, good to know, tnx.
I have a GSS340 or 341 (Walbro style) and yeah the pump (not the engine) hasn't run since, uhm, well, same day as the engine, actually. loll So August. 6 months. I should be ok then.

Scargo
01-19-2017, 11:47 AM
Agree with above. It would be good to have a FPR with a gauge.

FFRSpec72
01-19-2017, 11:57 AM
Agree with above. It would be good to have a FPR with a gauge.

A must for the track along with an AFR gauge

Frank818
01-21-2017, 12:26 PM
It's part of my post-inspection's improvement to-do list to have a FPR with gauge and re-doing the fuel lines.

Scargo
01-21-2017, 01:23 PM
I'm going to post a response to fuel supply for a EJ25 on the Fuel line to AN fitting size (http://thefactoryfiveforum.com/showthread.php?20880-Fuel-line-to-AN-fitting-size) thread rather than have it blow up here on your thread. The other has a good lead-in for my dissertation...:cool:

Frank818
01-22-2017, 07:25 PM
Well these guys are right, as always. I pulled out the feed line connector on the fuel pump and nothing at all came out of it, just some gas smell. Drained the ***** and changed my t-bolt clamp for a better one on the bottom portion of the filler neck. What a stupid place to put a filler neck on a gas tank... or any other tank. Filling by the bottom is never efficient for the purpose of what cars are designed for. Anyway that's done. Tnx guys.

wleehendrick
01-23-2017, 04:37 PM
Filling by the bottom is never efficient

It is for beer!


https://www.youtube.com/watch?v=wiu_IX14wLI

Hindsight
01-23-2017, 04:42 PM
What a stupid place to put a filler neck on a gas tank... or any other tank. Filling by the bottom is never efficient for the purpose of what cars are designed for.

I agree - makes zero sense to me.

Frank818
01-23-2017, 04:51 PM
It is for beer!

Loll!!! Funny one. Ok it isn't for fuel tanks, then. :)