LB7: Lb7 no start story

[OregonDMAX]

Driving home on Friday my truck died, quickly cracked open water separator to see if I had fuel at the Airdog. Nothing came out, figured my fuel gauge went bad and I had an empty tank. Got fuel but no luck, had it towed home and dropped tank and it was between empty and 1/4. Water separator has rust in it, never in my 7 years with this lift pump on have I ever gotten any water out of it and I check it fairly regularly.

So I guess I need a water separator at minimum, pump sounds so-so but it's held up great without a single issue all these 7 years, it's an AD165.

If the water separator doesn't fix it then it's probably the pump so I'll get it warrantied and I figure I'll add a sump and a new feed line from the pump all the way to the cp3. From the factory there are some pretty ****ed up lines, a return was actually sandwiched between the frame and tank and practically crushed flat. I know it's factory because I have the vehicles entire GM service history and I bought it only 190 miles after it's last visit to the dealer.

Anything else I should do while the tank is out and I have the truck apart. I've had a p0089 for a good while figured all new fuel lines was in order. I know it needs a cp3 and regulator i got a pretty sweet fuel lope at idle and data logs show it's out of fuel by the 1/8th mile on a 1/4 pass.

 

[aashton1206]

I have a 165 as well and I warranties a new pump a year ago. Great service, and the pump works great. No I had a recent issue will oem fuel lines collapsing so I ordered more fuel line from pure flow and I cut out all the quick disconnect fittings and used clamps. All new 1/2 line then the return line between the hard lines up by the firewall on the driverside was collapsed. So I did that to with some line I got from auto supply. Kind of just a peace of mind. On another note, the reason I replaced the return was I had a cascading fuel rail pressure. First I thought it was the fprv, it wasn't, the hardline tuning to the back of the block that was a return line was broken and priced together with fuel Line. That wasn't it either, long story short I found two kinks in the soft line and that was causing it. Got all new stainless lines from merchant and hose from pure flow.


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, Rick Fletes Dsp 5 on v2, 33x12.5 nitto at on 20 inch American Racing 20x10 wheels, Stage 5 Built Transmission by Mike Cole with triple disc billet low stall converter, 4 inch Injen cold air intake, Profab Intake Horn, Batmo Wheel, PPE Race Valve, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust axle dump, lbz cp3 pump, Dual Platinum AGM Duralast, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Upper Contol arms, Drilled and Slotted Rotors on all four Corners, FED Y Bridge, Shantz Custom Fab Traction Bars.

 

[zakkb787]

You could do a billet pickup while you're in there

 

[OregonDMAX]

I have a 165 as well and I warranties a new pump a year ago. Great service, and the pump works great. No I had a recent issue will oem fuel lines collapsing so I ordered more fuel line from pure flow and I cut out all the quick disconnect fittings and used clamps. All new 1/2 line then the return line between the hard lines up by the firewall on the driverside was collapsed. So I did that to with some line I got from auto supply. Kind of just a peace of mind. On another note, the reason I replaced the return was I had a cascading fuel rail pressure. First I thought it was the fprv, it wasn't, the hardline tuning to the back of the block that was a return line was broken and priced together with fuel Line. That wasn't it either, long story short I found two kinks in the soft line and that was causing it. Got all new stainless lines from merchant and hose from pure flow.

Yeah I'm going to run a new feed line for sure I've found a few rubber flex sections that are questionable at best since I've dropped the tank. Found a slightly linked hard line too so I'll prob just eliminate all of the hard lines completely.

 

[OregonDMAX]

You could do a billet pickup while you're in there

I'm going to do a sump since the tank is empty and out

 

[OregonDMAX]

Replaced water separator, I'm getting fuel up to the disconnect up at the firewall by the gpcm, not getting fuel to the cp3 or the cp3 took a shit and won't make rail. FML

 

[JRein]

Have you checked fuses and the edu/ign 1 relay?

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[OregonDMAX]

Have you checked fuses and the edu/ign 1 relay?

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Yeah, I got a blown 40a fuse but it's for trailering shit

 

[JRein]

Yeah, I got a blown 40a fuse but it's for trailering shit

Are you sure?

The 40s on my 04 are ign(s) and blower

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[OregonDMAX]

Stud #1 is trailer wiring, I should have mentioned that was the one it was

Also my fuse box is completely different, complete wiring changes in 03

 

[TheBac]

Honestly, it sounds like your CP3 died.

 

[OregonDMAX]

Honestly, it sounds like your CP3 died.

That's what I was hoping and not hoping, I've had a p0089 for about a year but you know how that goes it could be basically anything in the fuel system.

I did get a few surges over the past few months maybe once every 2 weeks it would randomly drop off and about 2 seconds later I'd get fuel again

The question is how do I test do determine if it's the cp3 or regulator obviously if it's the cp3 I'll do both but neither are in the budget

Fwiw the cts won't read any rail or any other pressures on an 02 or atleast mine

 

[TheBac]

Just a thought, but could the gearpump on the back of the CP3 have gone bad? Is that even possible?

 

[zakkb787]

That's what I was hoping and not hoping, I've had a p0089 for about a year but you know how that goes it could be basically anything in the fuel system.

I did get a few surges over the past few months maybe once every 2 weeks it would randomly drop off and about 2 seconds later I'd get fuel again

The question is how do I test do determine if it's the cp3 or regulator obviously if it's the cp3 I'll do both but neither are in the budget

Fwiw the cts won't read any rail or any other pressures on an 02 or atleast mine

Forgive me if I read this wrong, but my cts reads both rail and desired rail on my 02

 

[OregonDMAX]

Just a thought, but could the gearpump on the back of the CP3 have gone bad? Is that even possible?

I don't even know, maybe it imploded like a cp4
I don't even know what to do not being able to see any rail pressure is what's stumping me, too many variables, is my cts working, or is my pump shot... Did the pump shaft shear off... I don't even know ow where to begin, I do know I have fuel at the cp3 on the low pressure side

Forgive me if I read this wrong, but my cts reads both rail and desired rail on my 02

Mine won't read anything, is it because the pump is fried... Who knows

 

[SickLL7Crenshaw]

I don't even know, maybe it imploded like a cp4
I don't even know what to do not being able to see any rail pressure is what's stumping me, too many variables, is my cts working, or is my pump shot... Did the pump shaft shear off... I don't even know ow where to begin, I do know I have fuel at the cp3 on the low pressure side



Mine won't read anything, is it because the pump is fried... Who knows

The CTS should definitely read desired and actual. Doesn't sound good Sean. Highly doubt the pump gernaded though. But if it did take a sh!t it'll be a good excuse to throw a 10mm in its place :thumb:

 

[OregonDMAX]

The CTS should definitely read desired and actual. Doesn't sound good Sean. Highly doubt the pump gernaded though. But if it did take a sh!t it'll be a good excuse to throw a 10mm in its place :thumb:

I need to find a for sure way to tell that's what happens without taking it out yet, a 10mm is a little out of my budget but I'll do a sportsman at the very least

 

[2008lmmchopper]

Maybe think about switching out your sending unit. And this is one of the main reasons why I think its dumb some people run cat filters. Water in the fuel reads havoc. Also I use 1/2 in steal braided fuel line with AN fittings I believe the brand is Vibrant super easy to make up the lines you need and very durable.

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[2008lmmchopper]

I sure hope it isn't the pump bud if so I have a friend with a 02 and a bunch of spare stuff including stock pump if you need one I could get it for a bargain. His is all built but he saves everything. I'd just have to give him a ring and ask. Let me know.

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[02greysixer]

I have seen one run with a sheared gear pump shaft. As long as there was positive supply pressure it would continue to run. Just would only build about 8k/26k psi.

Easiest way to dead head the pump on an lb7 is to take the 2 old injector lines and cut off the rail ends. Weld the tube shut so you now have a block off plug. Disconnect both rail feed lines from the fprv/rail pressure sensor block on the drivers side intake clam and install your block off plugs. Now you have effectivly dead headed the pump into the rail sensor. Crank the engine over and see if you have rail pressure. If you do then you have a fubard injector. Hook up one side at a time to isolate it to driver or pass. If you still have no rail pressure then check the fprv. It could be pinned open from a piece of trash or something or broken spring. Disconnect the big return banjo from that block. If you have any fuel come out of the fprv it's bad. If nothing leaks from it, you have fuel going into the cp3, and no rail pressure when dead headed it's got to be a dead cp3.

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