Engine/Transmission (1998.5 - 2002) Fuel Leak - Need your help troubleshooting

[Devil Black Diesel]

I have a fuel leak that runs down the rear of the block (driverside) and drips off the inspection plate underneath the truck. It drips enough fuel to make a puddle the diameter of a hockey puck everytime I park it. The leak started after I installed my DD3's a couple weeks ago so I thought I had a leaky injector tube on 5 or 6, but I checked all 6 nuts and everything is dry up top. I climbed in to take a closer look and the fuel appears to leaking from the return fuel line below the "T" junction. It's hard to get a close look back there but I'm pretty sure it's leaking right where the nickel hardline meets the black fitting/tubing that runs back to the fuel tank. Any ideas how to fix?



The leak started right after I installed my injectors, what could have caused it? I definitely didn't bump anything down there, I can't even get in there to take a closer look.



What is the function of the return fuel line? Could the leak in the return line be causing my "lopey idle"? My FP is 23 at idle and 14 flatfooted on 5X5. The truck runs great but lopes when I'm slowing down for a stoplight or coasting through parking lots. It also lopes at idle while in N or P - No lope when in D or R with brake on.



Thanks for your help.

 

[Chasweaver]

Fule Leak

The only leak I ever had in that area was at the electrical connection on the lift pump.

 

[Devil Black Diesel]

Troubleshooting

I need to move this thread back to the top, I'm surprised I've only received one reply on this... . hasn't anyone else had to troubleshoot a fuel leak similar to mine?



Does anyone have the information on the Flourescent Dye that I can add to my fuel and troubleshoot with a black light?



Please help if you can.



Thanks

 

[Yooper1]

It's most likely your #6 injector. . Same thing happen to me. . Same area Too!

Check that. . You need a short 19mm to get to it. . But I'll bet that's the issue.

 

[TORQUE THIS]

Yup, check #6...



I also have had to tighten the "T" fitting for the return line, just a few days ago. Changed out injector tubes, never touched the T fitting, but it was leaking!

 

[Devil Black Diesel]

Troubleshooting

Thanks guys. Anyone else have any suggestions? I've checked #6 and I've tightened the "T"... still leaking.



Someone told me to reach around the back of the head and tighten the return line port, I'll try that next.

 

[rkressg]

Are you sure that it is the T that is leaking. Remember, there is 16,700 psi of FP on those injector lines. DO NOT check for a leak on those lines with your finger, use a piece of card board.



The fuel return line most likely got bumped when the fuel tubes were removed, and could have bent or cracked the return line. This could be letting air into the fuel system, causing a hard start problem.



-Rich

 

[dclassens]

I repaired a #6 injector line leak on a cat in a dozer that was creating a fuel leak running down the back side of the engine. I thought it was something else, but it ended up beng line to injector. I replaced line and reinstalled injector. Fuel was defiantly running down back side of block. The moral of the story was that it had to do with #6.

 

[tractorface]

Sounds like the T is leaking

Does not take much to get the T fitting leaking. Mine leaked after I changed the VP. Just tighten it uo. Since I don't have the stock lift pump mine was easy to repair. The T is simply a compression fitting so leaking is real easy. The other place to check is the OEM rubber hose quick connect just below the T fitting. That is the line that carries the return fuel back to the tank. Two pairs of Channel locks or two wrenches will be needed to tighten the T.

Good luck

 

[AggieJustin]

Since I'm not near my truck right now, I'll have to make do with looking at the diagram from the service manual.



#ad




So is the line from the "T" heading up to the banjo on the back of the cylinder head wet? If it's wet following the line above the "T", I'd guess a leaky banjo on the back of the cylinder head, possibly leaking past the washers. If it's below the "T", check all the connections on the "T" then check the quick connect below that.



With your fuel pressures where they are at, the excess pressure leaving the injector pump from the overflow valve could be causing a leak past any one of these fittings.

 

[SpicyJam]

I had the same leak for months till I figured it out, and since you just put injectors in, like I did when mine started leaking. Here is what I found. The delivery tube O-ring was bad, well it was new and I wrecked it on the install of the injectors. I ran to the hardware store and got a new one, thne went to Cummins and picked the right ones up, lol, I still have the hardware stores in there now for the past 6 months.

Trust me mine was leaking down the back of the block, down around the inspection plate, and making a mess everywhere. Later Jim.

 

[klaybus]

Thanks for the pic. I'll be checking mine tomorrow.



Clay

 

[proflow]

Just fixed a couple leaks on mine actually. Looked just like yours. Down left side of block. # 5&6 injectors both barely leaking. Also line from vp to t-fitting leaking , took apart , cleaned it , put some vasoline on it & tightened. No more leaks. Easiest way to check that rear fitting is to use a flashlight & mirror. I wouldnt tighten it any more if its not leaking. Good luck !---Proflow