Fuel system question

Pete_89T2 · 01-01-2011, 09:33 AM

For the stock fuel system, unless you follow the FSM procedure to depressurize the fuel system (i.e., idle engine, disconnect fuel pump connector, wait till the engine sputters out), opening up any of the fuel lines to/from the engine SHOULD result in a spray of fuel, even if the car was sitting for weeks, correct?

Reason I ask is yesterday I undid the fuel return line and then the fuel inlet line to the engine w/o depressurizing the system first (Duh, I forgot), and found by accident that neither line was pressurized. Fuel dripped out of both lines, but that was it - no spray. Car was last run just the day before, so the system SHOULD have held pressure for that long.

This typically means that one or more injectors is leaking down, depressurizing the system over time. Until I cracked open those lines, there was no fuel stench under the hood, so no external leaks. I was planning to send out the injectors for refurb/servicing as I normally do whenever I have access to them, but are there any other places the stock fuel system can depressurize itself internally like this? I suppose if my FP regulator was defective, pressure could vent back to the tank via the return line?

***TitaniumTT*** · 01-01-2011, 10:37 AM

It will eventually bleed back through the pump. Even with a brand new pump it will bleed back through the pump. Depending on the condition of the pump and the filter, this could take a few minutes or a few hours. But eventually, yeah Pete, it will drain back

RETed · 01-01-2011, 12:45 PM

TTT is right.
The fuel system will bleed down eventually.
I believe the FSM has a spec on which the system should hold pressure for X amount of minutes after the engine (i.e. fuel pump) is off.
It's not going to hold system pressure indefinitely.

-Ted

Pete_89T2 · 01-01-2011, 05:12 PM

Ok, thanks guys. Based on the last time I cracked open a fuel line after forgeting to depressurize the system first, I was expecting to get a high-octane bath, but I think in that case the car was only run <1 hour prior. Was obviously relived I didn't get the fuel bath this time!

01-01-2011, 09:33 AM	#1
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD iTrader: (1) Posts: 874 Rep Power: 15	Fuel system question For the stock fuel system, unless you follow the FSM procedure to depressurize the fuel system (i.e., idle engine, disconnect fuel pump connector, wait till the engine sputters out), opening up any of the fuel lines to/from the engine SHOULD result in a spray of fuel, even if the car was sitting for weeks, correct? Reason I ask is yesterday I undid the fuel return line and then the fuel inlet line to the engine w/o depressurizing the system first (Duh, I forgot), and found by accident that neither line was pressurized. Fuel dripped out of both lines, but that was it - no spray. Car was last run just the day before, so the system SHOULD have held pressure for that long. This typically means that one or more injectors is leaking down, depressurizing the system over time. Until I cracked open those lines, there was no fuel stench under the hood, so no external leaks. I was planning to send out the injectors for refurb/servicing as I normally do whenever I have access to them, but are there any other places the stock fuel system can depressurize itself internally like this? I suppose if my FP regulator was defective, pressure could vent back to the tank via the return line?

01-01-2011, 10:37 AM	#2
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son iTrader: (4) Posts: 4,581 Rep Power: 10	It will eventually bleed back through the pump. Even with a brand new pump it will bleed back through the pump. Depending on the condition of the pump and the filter, this could take a few minutes or a few hours. But eventually, yeah Pete, it will drain back __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

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01-01-2011, 05:12 PM	#4
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD iTrader: (1) Posts: 874 Rep Power: 15	Ok, thanks guys. Based on the last time I cracked open a fuel line after forgeting to depressurize the system first, I was expecting to get a high-octane bath, but I think in that case the car was only run <1 hour prior. Was obviously relived I didn't get the fuel bath this time!