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Duramax First Generation: 2001-2004 (LB7) Discuss the first generation (2001-2004 LB7) of the 6.6L Duramax diesel engine & associated components. Engine related discussion ONLY.

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Old 02-01-2009, 11:56 PM   #1 (permalink)
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Fuel Rail Leak?? HELP!!!

I tried starting my 01 duramax last night, with no luck. It cranks hard and sounds like its going to start, but just won't fire. Today I cracked the bleeder screw and it seemed like there was some air in the line. After pumping a few times, fuel started pouring out so I pumped until the primer button was hard and tried to start the truck. Nothing! I tried this several times and even had my wife try to fire up the truck while I was priming it. Nothing!!

I then noticed fuel dripping from the back of my engine. I first thought it was from bleeding the line, but it seemed like the more I primed the system, the more fuel that was dripping down. Some inspection with the flash light revealed the top of the motor was wet (passangger side only). It has to be fuel; I don't know what else it could be. Fuel is definitely sitting where the head mounts to the block, and looks to be coming from the fuel rail, or a line in that general area.

Has anyone else had this problem? I haven't had an opportunity to get the intake pipe and other "stuff" out of the way, so I haven't completely isolated the problem. It sure seems like that's where its coming from. Would that cause my truck not to start. I haven't noticed it running funny. You can't "over prime" the system, right?

To let you know, I have had some crazy luck with my fuel system over the last few months.

First, I had a hole in my fuel filter. That of course caused me to loose my prime, but wasn't that big of a deal.

Then, the fuel pump relay that sits in the fuse box went out. Not a big dea, but still caused my truck to not start for me.

Then, my truck didn't start about 10 days ago. I thought it was the relay again, but gave it one more shot. Sure enough, on the third try it fired and has ran fine since.

I have noticed my fuel gauge go goofy on me a couple of times over the course of the last couple of weeks. Shortly after filling up, my gauge would drop all the way to zero momentarily and then spike back up to full. Its done this to me two or three times. Is my truck possessed?

Sorry for the long post. I just wanted to get all of the information our there. I sure hope someone can help me. P.S. The truck only has 94k on it.

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Old 02-02-2009, 10:16 AM   #2 (permalink)
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Check your rubber hoses, there are SIX of them, three big ones(about 3/4in diameter), three small ones(about 1/2inch diameter). Two big ones going to and from the filter(about 8inches long), the other big one(about 2 inches long) goes from the FICM to the middle of the engine, one going from the test port(left side of alternator, small hose) to the middle of the engine, and the last two small hoses are somewhere in the middle of the engine.

I'm replacing my hoses because they are terribly dry rotted.

My fuel gauge used to do the same thing, check the connection on top of the tank(thought ot get to) and the ground strap(where the cab meets the bed, its on the frame)

'01 LB7 CCSB
Efi Live tuning from IdahoRob!!
Gmax-5 & 1058
s468/87/0.9 626rwhp on a weak fuel pump
Few other things
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Old 02-03-2009, 07:03 PM   #3 (permalink)
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I thought I figured it out but...

Like the title said, I thought I isolated the problem, but now I'm not so sure. Maybe the pictures will help explain things as well.

Like I said previously, I noticed fuel down around the passenger side of the motor. It looked to be under the fuel rail. Well I got my truck into my garage, and started ripping sutff off of it.

It looks like fuel is coming out of a T looking device mounted behind the alternator (maybe called the test port). It is the first device the fuel line runs into once it leaves the fuel filter.

I was able to take the upper portion off. It almost seemed as if fuel was leaking between the upper and lower portion. When I took the bolt out that holds the top one in place, it was covered in fuel. I don't see any reason why it should be. It seems the upper and lower portions are seperate devices and there should be no transfer of fuel between them. Initially I was hoping a gasket or something was bad between them. I now know that is not the case.

My problem is I don't see anything wrong with the top piece. I plugged two of the holes and try to blow in the third. I doesn't seem to be leaking anywhere.

I really need someone's advice. Do you think the lower piece is bad. It looks like a huge pain to take off, but I can do it if necessary.

The first pictures are of the entire assembly. The second to last picture is of the top portion of the device, the last is of the bottom portion with top piece removed.
Attached Images
File Type: jpg Fuel Problems 006.jpg (60.6 KB, 380 views)
File Type: jpg Fuel Problems 005.jpg (97.8 KB, 924 views)
File Type: jpg Fuel Problems 007.jpg (106.2 KB, 154 views)
File Type: jpg Fuel Problems 008.jpg (68.7 KB, 559 views)
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