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I have a neighbor with a 2002 duramax. It is with out any modification. The engine would spin with no start. Bled the fuel filter. Took several pumps to bleed. Truck started up and no problems for several days. Then it did the same thing. No leaks at all. What would be causing it to loose prime?
 

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Former GM Tech and parts
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Probably has a slight air leak letting the fuel return to the fuel tank. Good possibility it just needs a filter head rebuild. Pretty easy job and an inexpensive place to start off
 

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I have a neighbor with a 2002 duramax. It is with out any modification. The engine would spin with no start. Bled the fuel filter. Took several pumps to bleed. Truck started up and no problems for several days. Then it did the same thing. No leaks at all. What would be causing it to loose prime?

likely the filter head needs to be rebuilt. There is a check valve that prevents fuel from returning to the tank keeping the fuel line primed. When that leaks fuel returns to the tank, and the line empties.

Its about a 50$ difference to buy a new head vs rebuilding the old. Personally i would rather buy the new one and be done, but both options will likely fix your issue.
 

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likely the filter head needs to be rebuilt. There is a check valve that prevents fuel from returning to the tank keeping the fuel line primed. When that leaks fuel returns to the tank, and the line empties.

Its about a 50$ difference to buy a new head vs rebuilding the old. Personally i would rather buy the new one and be done, but both options will likely fix your issue.
Its a bit more than a $50 difference. The rebuild kit from Merchant Auto is $19.99 whereas a new filter head, for an LLY because they don't offer one for an LB7 any longer (and when it was available, the LB7 part was much more expensive), is $199.95 So there is a bit of a difference in price between them. And rebuilding one only takes a few minutes, so there isn't much of a time saving element there either
 

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Its a bit more than a $50 difference. The rebuild kit from Merchant Auto is $19.99 whereas a new filter head, for an LLY because they don't offer one for an LB7 any longer (and when it was available, the LB7 part was much more expensive), is $199.95 So there is a bit of a difference in price between them. And rebuilding one only takes a few minutes, so there isn't much of a time saving element there either
Oh i didn't realize they were that expensive for that truck. I picked one up for my truck (its an older filter not an LML filter) and it came with the filter and head for about 120$
 

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LHN...We ARE the Joneses
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whereas a new filter head, for an LLY because they don't offer one for an LB7 any longer (and when it was available, the LB7 part was much more expensive), is $199.95
Nah, not anymore. They're available from a variety of mfrs and at a reasonable price comparable to the later version.

I don't think the LLY-LMM filter heads were ever $200. Last one I bought several years ago, was on a Saturday and from the Dealer parts counter...$125.

And that's for a full assembly; the head, new filter, new heater, new WIF sensor...not just the filter head alone. Just the head now, can be found for $75-ish.

The only difference between the two head designs is the angle of one of the tubes, which the newer design can be adapted to fit on the LB7 by replacing the fuel lines with 1/2" bulk fuel line.

Which should be replaced anyway, when the filter head ages enough to start leaking prime, and could also be the leak source from those two lines and not the seals in the filter head.

(Note; not all seals are serviceable in the filter head with the rebuild kit....there's a possibility that after a rebuild, it'll still leak. But many times it is one of the 6 seals in the kit that is leaking.

Roll the dice.

As old as it is, it's unlikely that it still has the original head on it anyway....but it's possible.

Another note;
Parker-Racor made those old original filter heads and you can still buy 'em today, from various sources.
Racor PFF4245R2-04
Pics in this link, difference between the two seen.
https://www.parker.com/Literature/Racor/RSL/RSL0240_BUL_PFF4245R2-02_PFF4245R2-04.pdf
 

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Nah, not anymore. They're available from a variety of mfrs and at a reasonable price comparable to the later version.

I don't think the LLY-LMM filter heads were ever $200. Last one I bought several years ago, was on a Saturday and from the Dealer parts counter...$125.

And that's for a full assembly; the head, new filter, new heater, new WIF sensor...not just the filter head alone. Just the head now, can be found for $75-ish.

The only difference between the two head designs is the angle of one of the tubes, which the newer design can be adapted to fit on the LB7 by replacing the fuel lines with 1/2" bulk fuel line.

Which should be replaced anyway, when the filter head ages enough to start leaking prime, and could also be the leak source from those two lines and not the seals in the filter head.

(Note; not all seals are serviceable in the filter head with the rebuild kit....there's a possibility that after a rebuild, it'll still leak. But many times it is one of the 6 seals in the kit that is leaking.

Roll the dice.

As old as it is, it's unlikely that it still has the original head on it anyway....but it's possible.

Another note;
Parker-Racor made those old original filter heads and you can still buy 'em today, from various sources.
Racor PFF4245R2-04
Pics in this link, difference between the two seen.
https://www.parker.com/Literature/Racor/RSL/RSL0240_BUL_PFF4245R2-02_PFF4245R2-04.pdf


^^ that looks like the same filter head setup i got on amazon for my truck not too long ago. think i paid about 120 or so for the whole thing, head, wif and filter.
 

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Discussion Starter #8
Thanks for the quick replies. Giving him this information and him not to mechanical, he's getting new head.
 

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LHN...We ARE the Joneses
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he's getting new head.
:rofl
Nothing ever wrong with that. :teehee
 

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Nah, not anymore. They're available from a variety of mfrs and at a reasonable price comparable to the later version.

I don't think the LLY-LMM filter heads were ever $200. Last one I bought several years ago, was on a Saturday and from the Dealer parts counter...$125.

And that's for a full assembly; the head, new filter, new heater, new WIF sensor...not just the filter head alone. Just the head now, can be found for $75-ish.

The only difference between the two head designs is the angle of one of the tubes, which the newer design can be adapted to fit on the LB7 by replacing the fuel lines with 1/2" bulk fuel line.

Which should be replaced anyway, when the filter head ages enough to start leaking prime, and could also be the leak source from those two lines and not the seals in the filter head.

(Note; not all seals are serviceable in the filter head with the rebuild kit....there's a possibility that after a rebuild, it'll still leak. But many times it is one of the 6 seals in the kit that is leaking.

Roll the dice.

As old as it is, it's unlikely that it still has the original head on it anyway....but it's possible.

Another note;
Parker-Racor made those old original filter heads and you can still buy 'em today, from various sources.
Racor PFF4245R2-04
Pics in this link, difference between the two seen.
https://www.parker.com/Literature/Racor/RSL/RSL0240_BUL_PFF4245R2-02_PFF4245R2-04.pdf
They were much more than 200 bucks from a dealer when I worked there, and they are 199.95 right now on Merchant Auto's site. So yes, they have been that price in the past. Not saying they are still that expensive, but I doubt they are cheaper at the dealer than on Merchant's site.

I didn't go looking on amazon for how cheap I could get it, I went straight to someplace that I knew would show me a price and have it available...
 

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A lift pump is also a great solution to this.
 

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LHN...We ARE the Joneses
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Or a band-aid, turning air sucking leaks, into fuel spray leaks.
 
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True.

Although, I've never seen a comment after completing a LP install, where they said,
"oh boy, that was fun! Can't wait to do it ag'in." :teehee
 

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True.

Although, I've never seen a comment after completing a LP install, where they said,
"oh boy, that was fun! Can't wait to do it ag'in." :teehee
Ha! So true! Nothing like a good diesel bath while pinned under a truck! Such memories!
 

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I bought the newer style head for $100 at dealership today. Came with filter too.

Lb7 version was in stock but was $400

Get newer version and about 4 feet of 1/2 hose
 

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If it was me id do lift pump with filtration and rebuild the head . Its pretty dang easy
 

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I did the LLY filter housing (OEM eBay) and new lines for less than $100 a long time ago and no more problems.
 
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