Lb7 fuel leak on passenger side

[JudeH]

Hello guys, I'm new to this website. I have an 02 Duramax and just yesterday I started having a fuel leak on the passenger side of the engine. It only leaks when running. It's a very slow leak (about 1 drop every 5 seconds) but it's a consistent leak. I tried looking from the top of the engine when idling but cant really see where it's coming from. Any feedback would be appreciated.

 

[TheBac]

Have you ever replaced the rubber fuel lines to and from the filter head/ficm? Ever rebuilt the filter head? If not, then start checking those items.

 

[JudeH]

I haven't checked that. I also haven't owned the truck very long so I don't know if the last owner has. And I don't think the leak is coming from the fuel filter head either b/c the leak seems to be running off the back of the engine but not 100% sure.

 

[TheBac]

Rubber fuel hoses more than likely.

 

[JudeH]

Yeah, that's what I'm thinking. Couldn't be the high-pressure side right? Or else it would be a lot greater of a leak?

 

[2004LB7]

the fuel system runs in a vacuum unless the previous owner added a lift pump. if so then it's very possible for the fuel filter, filter head or rubber lines to leak. most of the fuel lines that are prone to leaking are on the passenger side

 

[JudeH]

I do have a lift pump. I have a fuel filter delete kit so no filter but I still have the head. it's probably just old rubber lines giving out. they are 20 years old lol

 

[KyleC4]

If it’s too tough to find they make a dye you can put in the fuel to help trace it out to source.

 

[Mogman]

It could be the fuel return lines on one of the rear injectors

 

[darkness]

It could be the fuel return lines on one of the rear injectors

It’s an lb7, returns are under the valve cover and the passenger side return is on the front of the head.

 

[JudeH]

yeah, the lb7 return line is under the valve cover. I'll try to find that dye you are talking about.

 

[JudeH]

if it is one of the fuel injector lines leaking, I hear it's pretty risky to take the lines off b/c you could knock dirt and rust down in the injector.

 

[ZeroGravity58]

if it is one of the fuel injector lines leaking, I hear it's pretty risky to take the lines off b/c you could knock dirt and rust down in the injector.

Yes it knocks a bunch of dirt into the top of the injector. I doubt it's a HP line leaking. It's probably one of the supply lines leaking. If so just buy hose and clamps and replace them all.

 

[2004LB7]

if it is one of the fuel injector lines leaking, I hear it's pretty risky to take the lines off b/c you could knock dirt and rust down in the injector.

if it's leaking at the injector there is a chance it would end up under the valve cover and in the oil. otherwise you'll be able to see the leaking line if it's not under the valve cover

 

[JudeH]

yeah true. most likely those 20-year-old rubber lines giving out. If it was a high-pressure line leaking, it would probably be a lot bigger leak, huh?

 

[2004LB7]

not necessarily a bigger leak. the volume of fuel the CP3 provides is not really that much. it's more about the pressure. it doesn't take much to drop the pressure of the CP3 to below what it would take to run the injectors and if it doesn't start then you really are only getting fuel leaking while cranking. if you leave the ignition on or the lift pump running does it continue to leak? or only when you try and start it?

 

[JudeH]

you know, I never checked when the ignition was in the on position. I only checked when the truck was idling. If it was the high-pressure side that was leaking would it be harder to start?

 

[2004LB7]

you know, I never checked when the ignition was in the on position. I only checked when the truck was idling. If it was the high-pressure side that was leaking would it be harder to start?

it can if the leak is large enough.

 

[JudeH]

ok, well the leak is pretty small.

 

[JudeH]

Ok, so I checked out the injector lines on the rail side, and they were all around 25 lbs-pounds and they are supposed to be 30 right?