Caps Injector Pump 4089664RX on a 8.3 Freightliner 04.

Phantom666

New member
Jan 20, 2025
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I have a FL80 Freightliner. I'm leaking fuel from one of the 6 small weep holes that surround the distributor module on a caps injector pump. I was told that this was my issue. So I replaced the distributor module and still have the leak. I would assume there should be reason or reasons why these weep holes leak. Clearly changing the distributor module was a mistake.

Also a note that when I turn my key and prime, the fuel leaks out straight away without running. Then after a bit of cranking it will start. However will stall a few minutes after that. Seems it's using the fuel that was brought up by the lift pump and then the fuel is dropping back down. Almost as if there's a clear line all the way thru each part of the pump to the main supply line. That's an assumption as I am only a layman.

I did buy a fully refurbished pump online. But the Chinese company tried doubling the price after I paid for it. By the time I got my cash back I'd spoken with Cummins. Who sent me the quote for a distributor module and labor. I was lucky in one sense that I never took it to Cummins, as I'd be in the same position but out a hell of lot more.

I'm new to forums like this, but Cummins strangle hold on all their parts and info means I can't find any help on this. And getting correct help from them is futile.

I'm hoping someone can give me some insight on this issue. Besides suggesting to buy another complete new pump. And perhaps if someone had a similar situation that got resolved. Cheers Shane

PS, I'll attach some pics for a reference.
 

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TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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I'm not sure you realize that this is a Duramax-based forum. Not much discussion of the other brands, let alone the larger semi-truck versions. There has to be forums out there for Freightliner trucks or those big Cummins engines. You might get lucky that someone here knows about those Cummins engines, but its not likely. Good luck to you.

Moved to Smoke Signals.
 

Phantom666

New member
Jan 20, 2025
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1
Australia
I'm not sure you realize that this is a Duramax-based forum. Not much discussion of the other brands, let alone the larger semi-truck versions. There has to be forums out there for Freightliner trucks or those big Cummins engines. You might get lucky that someone here knows about those Cummins engines, but its not likely. Good luck to you.

Moved to Smoke Signals.
Ok thanks. I was guided to this forum from another one. With a comment about more mechanics may be able to help on this forum.
Cheers
 

68ss

Member
Dec 30, 2019
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bac I sent him here as I have seen you all talk about everything. Did not know if you all had experience in this his or not.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,542
527
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Central OH
I'm not real familiar with the CAPS stuff, but it appears those weep holes are there incase of a sealing issue. The lift pump running during key on is to prime the system, once engine is running there's an internal pump that pressurizes the case of the pump. That's about all I remember, and long term you'll be better off changing over to an inline injection pump
 
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