davelinde

OK... any ideas?
I had two CP3 develop a slight leak, both repaired under warranty (but not without a fight). Currently running my third. The wisdom of this board was that the LP was starving the CP3, causing seals to get burned. So... I put in an FPG. When it was colder I was seeing pressures of about 6 psi down to 4 psi WOT, now that it's warmer I see about 7.5 psi most of the time. Ironically the isolator on the FPG began to leak... I could see a little fuel dripping off a few places under my truck, but not a lot. So today I climb underneath to see exactly where the leak is coming from. Yep, the isolator is leaking, but the CP3 is leaking too!

At first I thought it was the banjo bolt or some part of my gauge, but the top of the CP3 is squeaky clean, it's the bottom coated with fuel.

What's up with this? How in the WORLD could I eat 3 pumps in less than 3 years? I can't wait for the fight over getting this one replaced... Is the LP starving the CP3 at 5 psi? Any other theories? I'm about to hit the road and will need to just drive this as it is for another month and few thousand miles. Whe I get back I want all the info I can throw at DC to get this fixed once and for all.

PS - I am bone stock... really I am.

jtb51b

I think it has more to do with the (loosely called) fuel we get these days. I have heard tales of some additives or another that cause these problems, not sure of any that solve it.

Jason

TexasCTD

Dave,

I haven't had any problem with mine (so far) so im sorry that I can't help you more.

But I just wanted to post this thread link for you to see if it might possibly be related and help you in your fight with DC. Good luck and let us know what happens.


https://www.dieseltruckresource.com/...9&page=1&pp=15

davelinde

...interesting thread on fuel quality, thanx.

The irony here is that in talking to the DC rep last time I told him I was considering a FASS or other fuel system mod to help the next CP3. He said that would void the warranty for sure.

davelinde

Still pondering this. Of the three pumps that have leaked, this seems to be the worst. On the other two I had used PowerService on occasion during the winter. This pump has not gone through a winter yet (although it's run in the hottest ambients I'd ever seen 100+ for a few days...) and I had not used and PowerService.

One other thing I'm wondering... if I really got a new pump or if it was some kind of refurbished pump. ..and, if it was -- is the factory seeing "No Trouble Found" returns and refurbing them back into the parts supply chain. Just curious and still digging for info.

MikeyB

Check with Rich2500. He went through the same ordeal and ended up tearing down the CP3 pump and installed slightly larger o-ring seals.

MikeyB

v8440

Your 6 psi inlet pressure ought not be starving the cp3. If I understand correctly, gm uses NO LIFT PUMP AT ALL on the duramax, which uses the cp3 also. So, in the case of a gm, the absolute highest inlet pressure a cp3 could possibly ever see on a stock truck is 0.

davelinde

I've been avoiding dealing with this... but the leak kept getting worse.

I re-checked my fpg install to make sure the dealer couldn't point back to something I did and... sure enough, there was fuel leaking from somewhere around the banjo bolt. I just pulled it all apart and had two observations. First, the mechanic who re-installed it REALLY leaned on it - it took a bit to break it loose. Also, he used teflon tape to seal the threads on the elbow I had put into the tapped banjo. I never thought to check that because I had assembled it all so you could just disconnect a fuel line and unscrew the banjo without messing with my elbow or needle valve... oh well - when they replaced my last CP3 THEY caused the leak in fpg plumbing!

I thought the teflon tape on these threads was a no-no? What's done is done I guess. I've got it all back together now using permatex sealer and I used a threaded grease line instead of the fuel line I had before. Now I've just got to watch for leaks again... hopefully the CP3 was good all along. We'll see.

TexasCTD

Good luck with it Dave. You have definately had more than your share of troubles with CP3s.

And just think, winter will be coming on soon along with cooler temps. That seems to be when the problems start becoming more obvious and failures happening more often.

Smkndzl

Cummins has said all along one of the killers of the CP3 is high restriction on the return line. the CP3 on the dodge truck are different from the chevy , our has a inlet that flow to the low pressure side of the pump internally and then flow to the high pressure side also internally , you go look at the chevy and it flow to the low pressure side and then thru the fuel filter and back to the pump high pressure side of the pump. the 6.7 will be that way also in 07 with no more lift pumps. hopefully in the dodge also , the truck engine will no longer have lift pump.

fredbert

I'm about to install gauges on my rig, finally. Dave, exactly what flavor of Permatex did you use? Thanks! Glad to hear your third CP3 seems to be holding.

davelinde

liquid white teflon sealer.
I'm not thrilled with it though... at least half my connections eventually weeped fuel - then again, that could be the mechanic and not the material.