1,3 and 4 fuel lines leaking after priming fuel system

[Thecatcab]

Recently replaced my 99' 24v 5.9 fuel filter canister with the Genos Garage 1st gen kit after the stock unit lid finally cracked. After priming the fuel system by cracking lines 1,3 and 4 at the head I retightened the lines until fuel was no longer leaking. Cleaned with carb cleaner and compressed air around the fittings to make sure there was no seepage at idle. All looked good. Took it for a spin up the highway and when I got back there was seepage at those lines. I tightened it a bit more and took it for another spin after cleaning around the fittings. Seepage continues. I did not try and tighten them down any further as I don't know the correct specs.

Can anyone give me the proper torque specs for the nut that connects the supply line to the tubes at the head?

Also, If torqueing them correctly doesnt stop the leak..my youtube master mechanic certification would say pull the tubes and clean them up check the o rings and reseat and re tighten the supply lines.

Can the tubes be dealt with on their own without causing a seating issue at the injector?

seems to me like if you are pulling the tubes it would be a good idea to check the injectors too? To be clear i am not having issues with my injectors and though I am not looking for a shortcut I would definitely prefer to not touch what I don't have to for fear of causing another issue.

Any advice and recommendations are greatly appreciated!

 

[petersonj]

When I replaced injectors on my truck, I had a similar situation. After a couple of test drives I could see fuel dampness around the fuel fitting at the head. I would clean it with brake clean, but the weeping fuel would show up again. Another member suggested that I just run it and monitor it for continued leakage. I did so and all the evidence of the fuel leak disappeared. So, if you are only seeing signs of fuel weeping, you might give that a try. It could be some residual fuel - after all, bleeding the injector lines makes a bit of a mess, or if the high pressure fitting is weeping, a few miles of driving and lots of high pressure high frequency pulses to the injector line may make the seal between the metal to metal mating surfaces of the connection.

If that doesn't work, you could try just loosening a fitting, then retightening the fitting while the engine is running. Wear gloves to protect any fuel from penetrating your skin. The loosening / tightening strategy may dislodge foreign material or allow the mating surfaces of the fitting to seat in a different place.

- John

 

[DownByTheRiver]

It's important to tighten them in the right sequence (alternating between injector hold downs and fuel lines) if you're replacing injectors, but if you just cracked the lines just make sure no fuel is running down the manifold plate towards the back of the block...that's an actual leak. It's probably just residual fuel. Torque spec is 22 ft lbs.

 

[Joe Mc]

22# seems ridiculously low, but I do believe that is correct. Try John"s suggestion, I'd think that's a reasonable method. Also leave running while you clean residual fuel and blow off with air. Drive a bit and check every few miles.

 

[BigPapa]

This is the fuel system bleed procedure. Steps 1-7 reference bleeding the low pressure system up to the injection pump.

Step 8 says “Crank the engine for 30 seconds at a time to allow air trapped in the injection pump to vent out the drain manifold.”

 

[Joe Mc]

FSM doesn't suggest what to do if leaks after bleed process?

 

[Thecatcab]

Good Morning. Thanks for the advice and the specs! I have ordered the factory service manual from Geno's so I won't be in the dark on specs in the future. I was able to get the seeping to stop at 1 and 3 by loosening the connections and cleaning them again with carb cleaner and compressed air and reseating to spec (Did this for all of them). After a quick drive it was down to number 4 only for seepage however it was less prominent and only damp around the connection. I drove it for a few days to and from work and Still only damp. Went slightly over 28ft lbs. on that connection while rechecking torque (Gave me a little bit more after the click on the wrench, probably about a quarter inch more on the turn) and drove it for another day to work and now no more dampness or seepage.

Thanks for suggesting the high pressure pulses might help the seating I was hesitant to drive it not knowing if I would cause more damage. And next time I'll be more diligent on the cleansing of the surrounding area and mating points when reconnecting.

I got the 3/4 inch wrench in the door panel and will continue to monitor.

 

[petersonj]

I'll be more diligent on the cleansing of the surrounding area and mating points when reconnecting.

Even if your are more diligent about cleaning the surrounding area, you may still have an injector or two that will seep when the connection is loosened and then retightened. It is the nature of the beast. When the injector lines are connected for the first time (at the factory), the parts are new. The connection will form a seal that will be very reliable. The two metal mating surfaces will form a unique bond. Years later when that connection is broken, it will almost be impossible to mate the two surfaces together exactly as they were before - consequently a small seep of fuel leaking for awhile. Injector pop off pressure is over 4,000 psi. The injector and associated high pressure lines see well over 10,000 psi under normal driving. You can see how the rapid opening and closing of the injector would cause very high pressures and very high frequency pulses which result in hammering those fittings quite well.

High pressure metal mating surfaces are very reliable, but can be finicky when the connection is broken and then reconnected.

Glad everything worked out for you, Thanks for posting your results.

- John