LLY: New Cp3 leaking

bobbygerm

New member
Jan 12, 2016
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This old thread was very helpful to me, so thanks everyone ! I ended up replacing two reman CP3’s and both leaked until I decided to drop both tanks and clean them out and their sending units which were pretty dirty, and blow out the return line, but after cleaning, replacing and reinstalling everything as needed my CP3 still leaks at the common location on the bottom driver’s side near the block. Does anyone know of any other parts or check valves on the fuel system that would restrict flow while causing the CP3 to leak ? I’m at my wits end with replacing 3 pumps already. The 1st was a used one we had that was bad. Any help would be greatly appreciated. Thanks
 

bobbygerm

New member
Jan 12, 2016
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Also forgot to mention my fuel gauge was reading empty on a 1/4 tank and that the the sending units were plugged up. Had to replace the rear sending unit because it was rotted from a horrible design of the rear tank that lets the unit sit in a bowl allowing all kinds of stuff to accumulate there, absolutely stupid design. Anyways after repairs were done fuel gauges work fine but cp3 still leaks. Wondering if the cp3 could’ve blown a seal when the return is plugged and where that seal would be and if it's easily replaceable? Saw another link on another site stating the seal sizes and recommended going a little larger and I believe they give you the sizes. If this leak can happen from a return blockage, wouldn’t a simple pressure relieve valve right outside of the return be a simple common sense engineering solution so the pump does have to be replaced. I mean shitty dirty fuel is pretty common and I would assume over time this will happen eventually. Any input would be appreciated. Thanks again!
 

frankenstien

Member
May 25, 2015
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Fairbanks,Alaska
If theres a large enough restriction in the return, it will cause the front seal to leak, In my case, once i fixed the issue of the return, i have the same cp3 in there and its not leaking anymore.

Are you 100% sure its the actual cp3 front seal thats leaking? have any pics of where the fuel is leaking to? check all fittings, hard lines etc? hard lines om good condition? use leak dye to make sure where the leaks coming from?

did you just clean out the sending units or replace them? did you pop out and check the little fitting in the bottom? pics in post #38 and #42 of this thread.
 
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