Losing fuel pressure while off
08-12-2006, 02:51 AM
#1
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Losing fuel pressure while off I've done a search, and the few threads on this end with no solution or people asking "anyone?" several times.
Since last year, my car started taking longer to crank over after sitting. Recently, this was pinpointed as a drop in fuel pressure while the car sits off. My gauge reads 0 at initial start, with the first prime of the pumps (T-Rex in-line and Walbro 340m in-tank) taking the pressure to 20. A second prime shoots the pressure to 60 and the car will start, unless I let it sit there for a few seconds where it will proceed to drop off fairly quickly.
The first idea was that the 340m was the culprit, so I replaced it today with a Walbro 342s. The first few cycles of the car saw fuel pressure at 60, and never dropping below 55 while sitting (not started yet). However after a few drives of the car, the problem is back and doing it again. 0-20, then 60 and dropping.
At idle and driving around, it keeps pressure at 62 just fine, under WOT the pressure is steady as well, sometime seeing 70ish. But again, any sit time causes it to lose pressure and I have to cycle the car once or twice sometimes to start it off the bat.
I have done some reading and seen mention of some people having a problem with the check valve? Where is it, how do I test it, and can I buy a new one separate? I'm also looking into the feed line from the pump output in the tank (the brown colored plastic tube) as maybe it has a small split in it.
It seems there's no other leaks in the system from the injectors to the rails and etc.
Yeah, so help? Thanks
Since last year, my car started taking longer to crank over after sitting. Recently, this was pinpointed as a drop in fuel pressure while the car sits off. My gauge reads 0 at initial start, with the first prime of the pumps (T-Rex in-line and Walbro 340m in-tank) taking the pressure to 20. A second prime shoots the pressure to 60 and the car will start, unless I let it sit there for a few seconds where it will proceed to drop off fairly quickly.
The first idea was that the 340m was the culprit, so I replaced it today with a Walbro 342s. The first few cycles of the car saw fuel pressure at 60, and never dropping below 55 while sitting (not started yet). However after a few drives of the car, the problem is back and doing it again. 0-20, then 60 and dropping.
At idle and driving around, it keeps pressure at 62 just fine, under WOT the pressure is steady as well, sometime seeing 70ish. But again, any sit time causes it to lose pressure and I have to cycle the car once or twice sometimes to start it off the bat.
I have done some reading and seen mention of some people having a problem with the check valve? Where is it, how do I test it, and can I buy a new one separate? I'm also looking into the feed line from the pump output in the tank (the brown colored plastic tube) as maybe it has a small split in it.
It seems there's no other leaks in the system from the injectors to the rails and etc.
Yeah, so help? Thanks
08-12-2006, 05:46 AM
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by design the car is suppose to bleed fuel while the car is off
https://ls1tech.com/forums/fueling-injection/529855-should-fuel-system-hold-pressure-overnight.html
https://ls1tech.com/forums/fueling-injection/529855-should-fuel-system-hold-pressure-overnight.html
08-12-2006, 03:42 PM
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A second prime shoots the pressure to 60 and the car will start, unless I let it sit there for a few seconds where it will proceed to drop off fairly quickly.
08-14-2006, 11:16 PM
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No, I really can't at this point. I actually violated my own rule and re-used my o-rings on the injectors when I swapped intakes, even with only 5min of run time on them.
Maybe I need to pull the rail and replace the o-rings to kill that theory. However, there's no leaks from the area, so that's a positive.
Maybe I need to pull the rail and replace the o-rings to kill that theory. However, there's no leaks from the area, so that's a positive.
