Gelled or Cp3?

[Summit_Rider]

Today I was driving along with cruise set at 80. Looked over at my cts2 and as I’m glancing at it my actual rail pressure dropped from 21.5 down to 13.5 I continued driving 4 miles until I got to an off ramp, as I was driving up the off ramp rail pressure dropped to 2.5 and she died. So as I’m waiting for a friend to pick me up with a trailer I loosened the bleeder screw and turned my key on and my lift pump pushed fuel out the bleeder. Dumped half a bottle of 911 in the tank. I then took the fuel filter on the motor off dumped it out(fuel looked fine, not waxy) filled it half full of 911 put it back on, primed and still no start.

Could it still be gelled or is my injection pump out?

 

[LML6600DMAX]

Gelled?

Sounds like pump crapped out on ya.


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[zakkb787]

Yup. Look at actual vs desired rail when cranking and that’ll tell ya.

 

[clrussell]

I'd say gelled being it's an lb7 and not something that's common for fuel pump failures

 

[2004LB7]

Lb7s are known for developing high injector returns that can exceed the supply of the cp3 and thus drop rail pressure. If it is real bad it will be hard to start

I would do a return rate test on the injectors and cp3. This will give you a place to start before throwing parts at it

On my lb7 I had the tang on the back of the cp3 that drives the gear pump break and the pump had a hard time developing pressure. Took days to figure out

 

[Summit_Rider]

I just put 8 Bosch reman injectors in a few months ago. Long story but The previous owner put a reman cp3 in it from a not very reputable online company shortly before I bought it. I’m guessing it’s the pump. Have had a knot in my stomach about that pump ever since I bought the pickup.

I’ll know tomorrow morning. I’m gonna let it sit in our heated shop overnight, change filters in the morning and see what happens.

I already called Lds and they can have a new cp3 here by Friday if I order it tomorrow.

 

[Summit_Rider]

Got to the shop this morning pulled the dipstick to find a crankcase full of diesel. I drained it down and tryed to start it, no start and it makes no rail pressure while cranking.

I guess I need to order a cp3. Is there any gaskets or anything else I’ll need? I’m noticed lds has a master install kit for $100, should I get it?

 

[2004LB7]

You need to find out where the diesel is coming from. Often times it is from a cracked injector body or loose return line under the valve covers. The cp3 doesn't normally leak out the front shaft which is about the only place it can leak into the oil.

CP3s don't require any additional gaskets or hardware but you may want to look at your supply and return hoses and replace any that look old, cracked or show any signs of ageing while you are in there.

 

[Summit_Rider]

You need to find out where the diesel is coming from. Often times it is from a cracked injector body or loose return line under the valve covers. The cp3 doesn't normally leak out the front shaft which is about the only place it can leak into the oil.

CP3s don't require any additional gaskets or hardware but you may want to look at your supply and return hoses and replace any that look old, cracked or show any signs of ageing while you are in there.

I’ve put 500 miles or so on it after I put the injectors in it. I checked oil like a hawk after every time I drove it and it never moved. I’m thinking it’s gotta be the pump leaking.

If I pull my cp3 out will I be able to tell if it was leaking?

 

[Burn Down]

Pull the oil filler neck off, you’ll be staring at the cp3 drive gear. You should be able to see fuel leaking from there if it’s the pump. But as mentioned above it’s not a common area for the pump to leak. My guess is a injector as well.