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Discussion Starter #1
Think I've read every thread possible about similar issues, but nothing quite the same so here goes. Not a pro mechanic but not a complete novice either. Sorry for the length of post but wanted to provide what the truck has done and what I've looked at so far to diagnose and fix.

06 Sierra LBZ 4x4 with 130K, mostly just daily driver, owned since 30K miles, heavy tow with it about 4 times a year and also carry moderate loads when needed. No big issues with the truck up to now other than trans cooler line blowing and needing replacement. (fun job)

Anyway, I was on recent road trip after first 500 miles threw a P0087 on the interstate after recent fuel stop while going 80mph+ on a moderate grade, temp maybe 40-50 degrees outside, with no load. Felt loss of power, pulled over checked code and reset it with Torque app and bluetooth adapter. Truck was idling normal. Shut engine down, and then crank no start. Thought about filter head air leak and needing rebuild, so popped hood and primed it. Took a couple tries to fill the filter and get air out but eventually ran fine, no extra smoke, etc.

Took it easy and monitored fuel rail pressure and fuel use with my android to keep fuel use low, still thinking my filter head was pulling air and needing a rebuild. Tripped a P0087 again toward the top of a pass, pulled over cleared code again, pumped it back up, and continued. Made it back 300 miles after that but wasn't pushing it at all. Truck ran fine, no extra smoke, etc. Can't see demanded fuel rail pressure on Torque app but rail pressure runs up above 22K when accelerating and stays very consistent at about 4300 at idle. Mileage was about 21mpg.

When back home ordered filter head rebuild kit, new AC Delco Fuel Filter, and new WIF sensor. Rebuilt it, primed it, test drove and truck was running great. Next day took it somewhere and after it sat for less than an hour, lost fuel filter prime and crank no start. Primed and drove about 40 miles. Tripped P0087 on freeway again just before getting home.

Truck seemed like it was just starving for fuel due to air or lack of fuel supply. Read lots (if not all) related forum articles on P0087 and losing prime (thanks) suggesting new filter head, collapsing fuel supply lines, needing a lift pump, WIF sensor leak, schrader valve air leak, fuel cap, plus all the really bad expensive stuff like CP3 and injectors. After all the reading I still think it's a low pressure side fuel supply problem.

After that I inspected fuel lines and fuel cooler. Removed supply line covers on soft lines over driver's side valve cover and by the transmission. The valve cover line is noticeably out of round but doesn't look completely collapsed. Minor distortion on supply line by transmission. Decided to change them both regardless to avoid future problems. Found good article on that on this site. Ordered fuel line to spec from GM TSB which came in today and look way more durable, but waiting for warmer day to install them. Decided to let the tank fuel level drop further below 1/4 tank to make it easier in case I had to ultimately drop the tank to fix it.

To rule out potential errors on what seemed like a simple filter head rebuild, I also ordered a new complete AC Delco filter head, filter, and WIF on it for about $100 when I ordered the fuel line, thinking the spare parts would be good to have around even if that wasn't it. Got that, installed it, primed it, and pumped it up tight. Started right up and initially ran fine, but soon after lost prime again on same day, limped it home, and now with the fuel level at about 1/8th tank I can't get the filter to prime at all after an hour or so of trying.

I made an adapter and applied 10PSI to the fuel tank to see if I could find any leaks in the supply line. Couldn't find any, but maybe need more fuel in the tank to build up pressure from air faster to make a leak start showing. My lines look pretty clean and decent with no corrosion like I've seen in other forum pics from humid climates, but I haven't seen the top of the tank and fuel sending unit top (yet). The supply line and connection to filter head looks fine, and so does the line to the CP3 pump. Don't see any fuel leaks or smell fuel.

Problem with losing prime, or getting air in filter head has gotten way worse since initial problem a couple of weeks ago.

My plan from here:
- Replace the supply lines on next warm day off to rule that out. Also put some air through the fuel supply lines from transmission to just before the filter head to rule out an obstruction there.
- If it won't prime, put more fuel in the tank to see if there's and issue with the line drawing it out of the tank that would make it prime easier. Doesn't seem likely since first issue was after a recent refuel.
- Want to see if I can rent a gauge somewhere to check the vacuum off the port by the alternator to see if there's an obstruction in the line or vacuum out of whack.

Really interested in getting a Kennedy lift pump eventually, but would like to find the root cause of this issue first if possible.

BIG QUESTIONS I HAVE- Has anyone experienced similar symptoms and found a fix? Am I missing something else obvious that I need to check? Am I on the right track or are there other better things to check first?

Any help or ideas appreciated.
 

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One thing that sticks out is when you said this.
"and now with the fuel level at about 1/8th tank I can't get the filter to prime at all after an hour or so of trying.

Sounds like you might need a new pickup.
(002) GM 19148812 MODULE KIT, Fuel Tank Meter/Pump
MODULE KIT,FUEL PUMP CYCLE CONTROL (W/O FUEL LEVEL SENSOR)(FOR FRONT TANK)(INCLUDES 4)
Replaced by: GM Part: 19303428 $170.26

2006 Chevrolet Silverado 2500 FUEL TANK SENDER

Seems more people are putting on this
Beans Diesel Performance Fuel Tank Sump
BD-Power Flow-Max Sump Kit
 

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Man i had problems of losing power while towing i changed lines filter head and so on what i found was the in tank draw straw was loose fitting on the metal tube that exits the top of the tank . It seems like the plastic got hard from age and the fact that there is no hose clamp let it suck air. Replaced with fass 5/8 draw straw kit with bulk head fitting and no more problems. Like you i did everything else and the problem was at the very start of the fuel supply . Good luck .
 

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Before i droped my tank i used fass pump to drain tank. Did fass draw straw and fuel basket mod as per instructions . After install fass pump was able to pull the remaining 3 inches of fuel from the tank that pump wouldn't because of stock draw straw air leak. Like rvn4me says i think its your sending unit
 
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Discussion Starter #5
Hey rocken robin and rvn4me, thanks for the replies and recommendations on the fuel pickup. Good to hear some advice from someone that had a similar problem and actually fixed it! Definitely makes sense with what I'm seeing now as the fuel level has dropped more. I had pondered an in tank issue, but kept thinking about my first issue with P0087 with almost a full tank of fuel. With the issue you describe at the top of the draw straw it could have still sucking air into the filter head, albeit less with a full tank.

Definitely will be the next thing I check out, along with the FASS draw straw kit option.

Thanks again and will post results on what I find out.
 

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Discussion Starter #6
Seems fixed now. Here's what was done.

Changed out the rubber sections of fuel supply lines with 601-8 Parker. Purchased fuel line at https://www.mrostop.com for $4 per foot and Delphi FG0358 sender off of Amazon for $200 (vs $350 online for GM part and over $500 quoted by stealership).

The rubber section nearest the tank was also bad, not just the two sections over the drivers side valve cover and by the transmission. The one by the tank was kinking and the outside braiding was coming apart to the point that it almost looked like something had chewed on it.

Couldn't see any obvious leaks in the sender draw straw, but was worth replacing to eliminate all possible kink and air leak areas to get my DD running again. Unlike the GM part, the Delphi sender included the gauge fuel level sender. Mine had been inaccurate and would show empty after about 18 gallons gone and the Delphi unit appears to have fixed that.

After changing the lines and sender was able to prime the system quickly even with the lines starting out empty. Did take a bit to purge all the air out though. Truck is running fine now and holding prime. Will verify P0087 is gone after a longer highway trip with a load, but definitely not starving for fuel and pulling in air like it was.

One other side note on the repair is that it was easier to tilt the bed to access the tank, sender, and last rubber section of fuel line than it is to drop the tank. To tilt the bed just unplug driver's side tail lights from the harness, remove drivers side bed bolts, loosen passenger side bed bolts, and then pick the driver's side up and brace with wood blocks. Saw a youtube on this on a gasser GM truck and it saved us a bunch of time.

Still want to do the Kennedy lift pump, but replacing the lines and sender to get it running again was definitely worth it.

Thanks again for the input.
 

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Glad you replaced sending unit although the draw straw looks ok its when you go to take it off that you realize how lose fitting is gets with age .
 

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The description of the Delphi FG0358 says in part, "Patented Gen IV turbine pump provides better pumping with less energy use and withstands today’s harsh alcohol fuel blend" It does raise the question about the title and function, FUEL PUMP.

Any real, actual pumping function provided by this product?
 

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GM: 19303428 ACDelco: 19303428
- Designed with guide rods to retain proper alignment while reducing pinching
- Include a reservoir and jet pump to prevent fuel pump starvation when the fuel level is low
- Most strainers are placed inside the module to help reduce the chance of puncture
- Acetyl plastic for good high-alcohol fuel tolerance
- Electrical connections are designed to help eliminate high resistance due to vehicle vibration.

Product Description
An ACDelco GM Original Equipment Fuel Pump Module is a GM-recommended replacement for your vehicle’s original component, and consists of a fuel level sender, an electric fuel pump, and a jet pump. The jet pump maintains a consistent fuel level inside the internal fuel pump reservoir. These assemblies may be equipped with quiet Generation 4 turbine pumps with integral strainer socks. This original equipment fuel pump module has been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.
 
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Discussion Starter #10
Both the Delphi FG0358 and the ACDelco: 19303428 are just sending units not pumps. Saw lots of incorrect product descriptions advertising them as fuel pumps though. Without adding your own lift pump, all pumping is from the CP3 pump at the motor which sucks fuel out of the tank and can eventually cause the rubber sections of the fuel supply line to kink and collapse or draw in air through leaks in the line that can't be easily found since there is no positive fuel pressure on the line.

One main difference on the Delphi product is that it includes the fuel level sensor. My fuel gauge had always read empty with about 6 gallons of diesel remaining, and the new sensor included in the Delphi unit seems to have made it much more accurate.

As mentioned before, I would still like to add a lift pump but replacing the sender and rubber supply line sections took care of my problem for now.
 

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sad you couldn't add a gm low pressure pump in the tank [like a gas] eng truck
 

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Look what I found!

Like many others I have had the issue of losing prime. Being a DIYer and mechanically mediocre I had to give rebuilding the filter head a shot which entailed changing o-rings for $30. Cheaper than buying the whole head assy. The truck has 140,000 on it and the o-rings were worn and leaked when priming the filter. So, was this the real issue? Maybe a portion of it but once I had it on the bench and started changing the o-rings something caught my eye. Under both fixed rubber diaphragms (those that are not serviceable) there were 4 pieces of what looked like thin blades of artificial grass. They were stuck under both diaphragms, not allowing them to seal, hence it lost prime. No idea where they came from. Anyway, here's a pic.

Steve
 

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