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Still bleeding off fuel pressure

This is a discussion on Still bleeding off fuel pressure within the General Help forums, part of the LSx Technical Help Section category; A couple months back, I upgraded to a Racetronix fuel pump and hotwire setup. Prior to the swap, upon energizing ...

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    Still bleeding off fuel pressure

    A couple months back, I upgraded to a Racetronix fuel pump and hotwire setup. Prior to the swap, upon energizing the ignition the fuel pressure would jump up to the high 40's or so and then (without starting the engine) quickly bleed off. Everything in the bucket is new, including the flex hose, and I swapped out the pressure regulator 3 times (GM sold me one for a V6 which worked great if I only wanted 48-52 psi). I do not have any external fuel leaks and my fuel pressure while driving is now hanging right around 60 psi at idle and then drops to 58 when I get into the throttle.

    Unfortunately, the pressure still bleeds off exactly as it did before. I energize the ignition and again, without starting the engine, it will jump up to about 50 or a bit higher and then fall right off to nothing within a few seconds. At this point, I have to think it is an injector (or injectors) that is simply leaking and allowing the pressure to fall like that. Since the volume of the fuel system isn't all that large, it seems that it wouldn't take much of a leak for the pressure to bleed off. Thoughts?

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    Veteran 0rion's Avatar
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    pump is new, regulator is new, and flex hose is new. There's just really not a ton of other options. The only thing I would be curious about is if the new hose is cracked or the regulator was bad out of the box. Stranger things have happened. What about if you pull the rail out of the intake and pressurize the system and watch the injectors for a drip? Never done that but to me in makes sense in theory. I would think it would have to be a pretty substantial leak to bleed the pressure down that fast.

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    That was exactly my plan unless someone posted up another possibility.

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    I feel as though if you were bleeding that much off due to an injector you one would have a significant leak and two would hear it every time you tried starting the car (if it would even start) I have had a leak at the injector it is definitely noticeable. It was due to the injectors not being fully seated in the intake.
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    Hmmmm. I could pull the pump again - just wish there was enough slack in the lines back there to power the pump up with the bucket out of the tank.

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    Senior Member JayTA98's Avatar
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    Jeff I had a similar issue when I upgraded my pump. It ended up been a pin hole in the new racetronix flex hose. I see if I can dig my videos.

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    I ended up using a solder pen and melted the plastic pinhole until it was sealed again. I told racetronix about the issue but they refuse to claim it was a factory defect. I also had an issue with their upgrade harness. The pump was not getting any power. It ended up been a faulty contact in the ground wire eye terminal that goes to the ground bolt by their included fuel pump relay. I called them and same response, that is was not possible. I cut the connector off and used a new crimped one. It worked while I owned the car.
    Last edited by JayTA98; 09-15-2014 at 06:18 PM.

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    Could you see the pinhole?

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    Senior Member JayTA98's Avatar
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    Quote Originally Posted by pajeff02 View Post
    Could you see the pinhole?
    yes but I had to look real close. I'm not saying you are having the same issue but if you pull the pump out look very close at the flex tube.
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    Hmmm. Absent seeing something obvious in the kinked line, maybe I could pull the pump, drop my shop air pressure down to around 10-15 psi, submerge the pump and bucket in a container of fuel and then pressurize the pump outlet. If it has a hole it should result in a visible leak, right?

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    Senior Member JayTA98's Avatar
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    Yeah it could work. If you ahve a leak put some some gasoline in the flex tube and move it the pump around making sure each section get fuel.

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    I think no matter how you slice it you're heading towards pulling that pump again. I just can't see an injector leaking down that much fuel that fast. I guess it's possible but I would think it would be pretty obvious when the car started up that a cylinder was flooded. My concern is how much trouble you've had with getting the right regulator in there. You're sure you have the right part number in there and did the install go smooth?

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    That much from a leaky injector would most likely cause a hydrolock.

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    Senior Member JayTA98's Avatar
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    I agree with the rest if you had a leaky injector it will take sometime to start the car due to flooded cylinder

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    Chasing the bleed down issue, I elected to replace the regulator. The local dealership sold me a 6 cylinder regulator, and then I purchased the correct regulator on line. Removal and installation of the regulator is pretty straightforward as it is simply held in with a spring clip. The only reason I suspect something other than than pump assembly is that the problem has persisted from old pump, to new pump, and through 3 different pressure regulators.

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    Two most common areas of concern are the fuel injector nozzles and the pressure regulator. Sounds like you're isolating 1 of the 2 with changing out the regulator again.

    Is the car hard to start after a short engine shut down or does it have prolonged crank times?
    It's on jackstands.

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    It was firing right off, but now that I keep the car up in the building I am disconnecting the battery, so can't really tell as it usually starts and immediately stalls upon first startup. It has always done that after the battery has been disconnected. As to restarts once the car is out and about, haven't noticed an issue but it has probably only been driven 2-3 times since the pump swap.

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    Senior Member JayTA98's Avatar
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    any luck Jeff?

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    Maybe if I had time to work on it. It'll happen here soon.

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