LLY: Surging issue

[levimeloy]

'04 LLY, s&b intake, 2" level, 33's on 20's, no chip, everything else stock. It's not throwing any codes that I know of, no SEL. I believe the issue is fuel related.

Took the truck to the shop to get trans flushed, coolant flushed, and while it was there decided to get the fuel filter replaced. Got the truck back and it's surging sometimes at idle but mostly when driving around. It's having hard starts and sometimes will die a couple minutes after being started. There are no fuel leaks, and no other leaks at all.

I've tried to do some research and what I think it is, is the fuel lines coming from the tank might be corroded, or when they changed the fuel filter they messed something up. Can't figure out which one. I figured I'd give it some time to see if it would develop a fuel leak but it hasn't. Is there a way to test the fuel lines or should I just replace them and go from there? Thanks!

EDIT: forgot to mention, when it surges, rpm's increase.


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[830king]

Since they changed the fuel filter I'd start there. Filter may not be 100% sealed and getting a little air in the system.

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[zakkb787]

I'd say your filter head needs rebuilt. Sometimes when they crack open the filter it messes with the other internal filter head seals. Probably letting air into your system. You can rebuilt it yourself which can be hit and miss or you can buy a new one. That's where I'd start

 

[Woodster]

Since they changed the fuel filter I'd start there. Filter may not be 100% sealed and getting a little air in the system.

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I'd start with this.

 

[levimeloy]

Ok thanks guys. Gonna take a look at it today


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[2004LB7]

if you have an air compressor you can try and pressurize the fuel tank with a few PSI and see if the filter or housing leaks

 

[WVlogger]

My LB7 was surging bad when it was warm. Put a new fuel pressure regulator on it and now it is smooth as silk.

 

[levimeloy]

My LB7 was surging bad when it was warm. Put a new fuel pressure regulator on it and now it is smooth as silk.

Ok thanks. Pretty sure that’s what we came to, did a pressure test and it was fine, that’s next on the list just gotta find some time and to do it


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[DefiantArms]

My money would be on FPR mine surges so bad it will push through the brakes at a stoplight sometimes.