Lift Pump Install led by fuel return leak at motor

The owl

New member
Feb 22, 2017
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Hey guys, I know this is common on the 2015.5+ but never heard of it on an LMM and found 1 thread of it happening on an LLY.

I installed my new lift pump finally. I went with the AFE DFS780. The install went well/as expected, I fired the truck up and it was running smoother than before seemed to have better throttle response. Very pleased!

Now the nightmare begins.... As I'm letting the truck idle and securing the last of the new pump wiring. I notice a fuel leak from the bellhousing (not filter head) and it's more than a trickle, it's a fine stream. Truck is still running great, so it must be return. Well under further review, I found the culprit and it is the rubber return hose fittings on the T under the coolant tube (behind the AC comprrssor.) I also notice a drip or two at the return on the driver's side rear fuel rail by where you put a race valve/plug. Which I can't tell if it's traveling from the main leak or if it is a separate one. I have found one other thread where someone posted this, but it doesn't seem too common. Is there something I did wrong or just bad luck?

The shitty part is, to fix any of these I can't think of anyway except to pull the intake manifold off? And I'll use better fuel line clamps for sure! Any suggestions?
 
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
Hose are probably just old. Those get neglected all the time and need replacing over the years. Pull the accessory brackets and upper rad steel hose. Should be able to get to everything then. I would replace all the hoses in the engine valley you can. Coolant and fuel. She’s probably due
 

The owl

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Feb 22, 2017
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Yep, that's where I'm headed! Hopefully I can pick some up at the store. And more fuel injection hoseclamps as these spring fittings are a bit junky. I'll report back, once I get some more underhood time.
 
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The owl

New member
Feb 22, 2017
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Well after a very fun day in the shop I have this all fixed. The lift pump essentially provided too much pressure for every single spring clamp on the factory system. All has been replaced with upgraded line and fuel injection hose fittings. Glad it's fixed, but what a pain!

It actually looked like they were leaking a bit before but I'm sure it was while driving, not parked at idle.