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2004 Yukon XL 2500 LBZ

Will L.

Well-Known Member
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Location
Boulder City Nv
Yeah, last one I did on my friends truck there was no signs of leaking. But the pump it up scenario when he called I said just order the kit. Helped him swap in the kit and no more issue.

Usually there is at least a little dirty spot where the fuel collects dust, but his was clean. Sucking air when off somehow was my guess.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
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ZEPHYRHILLS FL
Staff #102
Stock without a lift pump the filter head will be dry because it is sucking air in since the fuel system runs under vacuum. With a lift pump you almost always get a fuel leak thats visible since the fuel system now runs under positive pressure.
 

BigDogYJ

Active Member
Messages
416
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155
Location
Kommifornia
Thread starter #103
Stock without a lift pump the filter head will be dry because it is sucking air in since the fuel system runs under vacuum. With a lift pump you almost always get a fuel leak thats visible since the fuel system now runs under positive pressure.
Hmmm. That’s what I thought. So there’s no sign of leakage at the filter head or at the soft lines coming off the filter head. Strange thing is after the two times it acted up it hasn’t happened since.
I’m wondering if it somehow was caused by the 1/8th tank of fuel and being parked on a slight incline before parking that night?? I ordered the MA rebuild kit so I have it in case I need it. I’ll keep driving it and see if it acts up anymore.
My understanding is that the Fass pump is a flow thru design since the truck runs fine if I pull the fuse for the Fass. So if I was low on fuel and on a slant, and the bottom of the pickup tube wasn’t submerged could the fuel in the line drain back? I can’t see that happening but maybe it’s possible.

When it happened the first time it didn’t even try and fire just cranked like there was no fuel. Then it finally fired up after the 4th or 5th attempt. I Shut it down 15 mins later to get fuel and first crank took an extra second or so but it started up on the first attempt.

Just strange. That’s all. Thanks for the input guys.
 

BigDogYJ

Active Member
Messages
416
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155
Location
Kommifornia
Thread starter #104
California allows the swap as long as all the original emissions equipment is installed that came with the engine. And the engine has to be from the same model year or newer. Then it gets inspected at the smog referee station. Once that’s done it’s all legal. Then I transfer my reg to a different county that doesn’t require bi-annual smog inspections.
So it’s all legal. Last friday I got it inspected by the smog referee and they issued a BAR label which basically approves the engine change and the vehicle can now be emissions tested as if it were a 2006 2500HD with the LBZ, and it’s all legal.
Haven’t put too many miles on it lately just a lot of around town driving. MPG seems to hover around 15-16 around town. We’ve got some trips coming up in a few months and I can’t wait to get it back out on the road.
 

BigDogYJ

Active Member
Messages
416
Likes
155
Location
Kommifornia
Thread starter #105
Hmmm. That’s what I thought. So there’s no sign of leakage at the filter head or at the soft lines coming off the filter head. Strange thing is after the two times it acted up it hasn’t happened since.
I’m wondering if it somehow was caused by the 1/8th tank of fuel and being parked on a slight incline before parking that night?? I ordered the MA rebuild kit so I have it in case I need it. I’ll keep driving it and see if it acts up anymore.
My understanding is that the Fass pump is a flow thru design since the truck runs fine if I pull the fuse for the Fass. So if I was low on fuel and on a slant, and the bottom of the pickup tube wasn’t submerged could the fuel in the line drain back? I can’t see that happening but maybe it’s possible.

When it happened the first time it didn’t even try and fire just cranked like there was no fuel. Then it finally fired up after the 4th or 5th attempt. I Shut it down 15 mins later to get fuel and first crank took an extra second or so but it started up on the first attempt.

Just strange. That’s all. Thanks for the input guys.
To follow up with this, I haven’t changed anything just filled it up with fuel and it hasn’t had an issue since. Must have just been the angle we were parked and the low amount of fuel in the tank. I ordered the filter head rebuild kit from merchant and replacement soft lines just so I have them.
 
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