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2006 LBZ losing fuel prime

Stingray

Toyota Junkie
CAL4
Joined
May 19, 2020
Member Number
235
Messages
1,186
Loc
So. Cal.
I have an issue that's come up.

The fuel primer /filter seems to lose prime after sitting about an hr or so.

Back story is I drove it about 250 miles, when I shut it off it sat about an Hr. when I went to restart it fired and ran about 30 seconds and died. I checked the fuel primer pump and it was soft, so I pumped it up ( I was in the desert 112*) I thought maybe a heat issue. It re fired and ran another 30 seconds and died. this time I re primed, re fired, and held the throttle at abot 1500 rpm for about 20 seconds. This time it stayed running and as long as it was running it was fine.

I probably re started it 15 times before getting home from this trip, it did lose the prime each time, but it seemed like if I started it and held the rpm's up a little it would re prime and keep running.

Right now I'm leaning towards the filter assembly/primer housing.

But does anyone have any insight?
110k on the truck.
 
I have a 07 LBZ,same thing here. I rebuilt the pump head,didn't fix it.
I bought a new gm filter head, didn't help either.
I'm thinking I have a small hole or crack in a fuel line.
If you find out,let me know too.
 
I have a 07 LBZ,same thing here. I rebuilt the pump head,didn't fix it.
I bought a new gm filter head, didn't help either.
I'm thinking I have a small hole or crack in a fuel line.
If you find out,let me know too.
So how are you handling it?
 
The filter head units are known to cause issues.

What filter are you guys running on the filter head unit? If you guys are running aftermarket filters that need adapters to be used on the filter head unit. Try removing those, replace the o-rings in the filter unit and use a wix (factory style) filter.

If this doesn’t work, I’d ditch the head unit and install a lift pump (just a suggestion). I did this on my LBZ years ago, and haven’t looked back.
 
So how are you handling it?
Just priming it when it needs it. I only drive it when I tow now,so maybe 1-2 times a month.
It's towards the end of a long list of other things to fix around here.
Have thought of a lift pump.
Why are the FASS and airdog so $$$$$?
 
IMG_20200407_155438379_HDR.jpg


IMG_20200408_113755426.jpg



This is what the last one I diagnosed looked like. Ended up with all new lines and hoses on the feed and return side, new filter head, and the leak was actually at the CP3


This one is a LB7 or LLY I don't remember, but the fuel system is pretty similar across the years.


A lift pump is a good upgrade, and will show you the general vicinity of the leak before you lift the cab.
 
Not looking to lift the cab, gonna start with the filter head, and work from there.
 
Piling on with the others - rebuild the filter head for a cheap starting point, but also start looking at getting a lift pump either way. Having the system under slight pressure is better than having it under vacuum, and could potentially help the CP3 survive longer. Although, they have a pretty long life already. If your system has leaks, right now without a lift pump it's potentially ingesting air into the system and then pressurizing it in the CP3 leading to cavitation issues in the pump and injectors.

My bet is filter head, but there's also several rubber lines throughout the motor that could be dry rotted as well.

Also, you don't need to pull the cab to do a CP3

Here's a complete rubber fuel line kit. Lincoln Diesel is top notch. They also have a filter head rebuild kit.
 
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edit: I never posted this yesterday so its dated info.

My opinion on Duramax's is shit can the vacuum pumped low pressure fuel system ASAP before it kills the lift pump in the cp3.

Fass, Airdog, Kennedy or Holley/Mr. Gasket are all better at stock power levels than OEM.
 
UPDATE

Replaced the Fuel filter head, Filter, Eliminated the WIF sensor, Primed the system and it seems to have solved the issue for now.

Something I am going to do is the fuel line kit, that seems like a good maintenance item at 100K.
 
The filter head units are known to cause issues.

What filter are you guys running on the filter head unit? If you guys are running aftermarket filters that need adapters to be used on the filter head unit. Try removing those, replace the o-rings in the filter unit and use a wix (factory style) filter.

If this doesn’t work, I’d ditch the head unit and install a lift pump (just a suggestion). I did this on my LBZ years ago, and haven’t looked back.
I'm buying factory GM filters in bulk and replacing at 10K
 
edit: I never posted this yesterday so its dated info.

My opinion on Duramax's is shit can the vacuum pumped low pressure fuel system ASAP before it kills the lift pump in the cp3.

Fass, Airdog, Kennedy or Holley/Mr. Gasket are all better at stock power levels than OEM.
are those replacements for the factory filter head?
 
are those replacements for the factory filter head?
No they are just electric lift pumps but once you install electric lift pump you can re plumb the fuel system with a proper two filter system and none of that all in one bullshit isuzu used.
 
My LB7 did the same thing. You need to check the seals and o rings. That fucker has to be on there TIGHT. When mine had issues, I got another 1/2 to 3/4 turn on it and no more issues.

I also replaced the janky plastic bleed screw with an aluminum one.
 
My LB7 did the same thing. You need to check the seals and o rings. That fucker has to be on there TIGHT. When mine had issues, I got another 1/2 to 3/4 turn on it and no more issues.

I also replaced the janky plastic bleed screw with an aluminum one.
So up until now I've changed filters and never touched the bleed screw, just pumped the primer until it was solid and fired it up, now I have an aluminum bleed screw and deleted the WIF sensor with an aluminum plug.

Today it got a full service, fuel, oil, trans, air. @110K.
 
They’re great trucks, I miss my LBZ all the time.
I'm probably one of those guys that bought a diesel and didn't need it, I tow a 13k trailer from time to time, but it's mostly empty.

It just turned 110K and been a solid truck, no complaints.
 
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