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Discussion Starter · #1 ·
Ok so I have a lly with stock injectors and stock cp3. I put a air dog 2 4g 165 on the truck and after a few weeks I had some fuel leaking from my rubber fuel line the one that runs over the y bridge. I'm not positive on what it feeds or if it's a return line. So I put some better clamps on the line but still seems to be leaking a bit. The line is wet I'm getting fuel back into the valley. Would this be a cause from the lift pump installed? Has anyone else has a similar problem like this. I dont have a pressure gauge on the line might end up ordering it tonight so when I do adjust the pump I can see what pressure its holding. Thanks for the input. Deff could use some information on this
 

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Ok so I have a lly with stock injectors and stock cp3. I put a air dog 2 4g 165 on the truck and after a few weeks I had some fuel leaking from my rubber fuel line the one that runs over the y bridge. I'm not positive on what it feeds or if it's a return line. So I put some better clamps on the line but still seems to be leaking a bit. The line is wet I'm getting fuel back into the valley. Would this be a cause from the lift pump installed? Has anyone else has a similar problem like this. I dont have a pressure gauge on the line might end up ordering it tonight so when I do adjust the pump I can see what pressure its holding. Thanks for the input. Deff could use some information on this


im not sure what hose in particular you are talking about so i cant tell you for sure what the issue is. My guess would be that in a round about way the lift pump caused the leak, but only in that the hose was likely dry rotted and cracked to start with, and since the system usually runs under vacuum instead of positive pressure, there was never a leak before, because it drew air in instead of pushed fuel out. Id go to the auto store and get a foot or two (it sounds like a short hose from what you described) and replace the hose. Make sure what you get is bio diesel rated as as some fuel comes pre blended with bio diesel and not all rubber hose is rated for it (like the factory lines on your truck). Clamping down on the hose wont do much if theres a crack in it somewhere thats seeping fuel.
 

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I think you're talking about the crossover line for the injector returns. It's fairly small, right? Off the top of my head I think it ties back into the main return line on the front passenger side near where the pressure measuring port is.

Either way it's probably just old and worn or rotted. Maybe a mouse chewed through it but it shouldn't have anything to do with the lift pump.

The main fuel lines on the engine connect at the back of the engine near up too on the driver side. You probably saw this when installing the lines from your lift pump. There's a big supply one and a smaller return one. From there they are hard lines that noodle their way over to the front on the passenger side where the supply goes into the filter, then back forward and into the cp3, then out to the fuel rails. The return lines gets connected to all the various discharges up in that area too, including the line which I believe is the one that's leaking for you.

Bear in mind this is off my memory of my LBZ so it might be a little off from your LLY but should be close enough to give you an idea of what you're looking at. There's honestly a lot of twists and turns in the hard lines to get them to conform to close to the engine and all the accessories, it's pretty remarkable but bakes it hard to trace them. The end result is a nicely packaged engine module they can just drop into the frame and hook up in probably minutes!
 

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Discussion Starter · #4 ·
Thanks for the input. I had done the head gaskets a few months back with all new injectors cp3 hard lines ect. I did replace all rubber lines with new oem lines. And yes it's the small 3in hose that I believe is for the retune line seeing how small it is. I kinda thinking it was the old junk clamps I used i shouldn't have but new it was easy to get too with the airbox out. I did replace the clamps with bad clamps got it good and tight and cleaned out the valley with a flush of water. I also turned the pump down a 1/4 turn and ordered a fuel pressure gauge. Going to tie I to the filterhead vs pump as that's closest to the motor. Thanks again. Well see what happens
 
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