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Discussion Starter #1
my fuel pump went out on my 05 duramax and i need to know if its in the tank or on the rail?
 

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What makes you say it is the fuel pump? There is only the CP3 injection pump which draws fuel from the tank via suction to the valley of the engine where it compresses it into the rail. I replaced mine at 300,000 miles, fair amount of work, nothing complicated, just a lot of parts.
 

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What makes you think it went out?

On a stock Duramax there is no electric pump in the tank or on the rail -- unless you have dual tanks.

The Bosch CP3, mechanical pump mounted in the engine valley, pulls the fuel from the tank via vacuum.

Maine Towing - faster on the draw than me!
 

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Discussion Starter #4
well maybe its not out.. ive asked 3 or 4 mechanics and theyve told me 2 or 3 different places.. ive got a 100$ pump that looks similar to fuel filter in looks.. but dont know where its located.. it wouldnt be the fuel injection pump would it? thats what im told is in the valley
 

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The CP3 is the only fuel pump on a stock truck, half of it is the injection pump and the other half actually sucks the fuel all the way from the tank. Are you throwing any codes? Do you know if your truck has had a "lift pump" installed on it? Would be after market, there are a variety of styles and they can be plumbed into the fuel system anyplace before the CP3 but most likely either under the cab between the tank and the engine or on the passenger side of the engine near the fuel filter.
 

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Discussion Starter #6
there hasnt been a lift pump installed that i know of.. no codes are coming up.. ive got a couple diagrams that show the new pump i got being in front of the tank.. when i checked the valve under the hood im not getting any fuel pressure at all.. i just hope its not the injection pump bc theyre pretty expensive.. but ive also heard that the injection pump doesnt normally go out.. they more less come apart.. that was from chevrolet..
 

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So what is your truck doing? How many miles on it? The only factory pump is the CP3, not sure what diagram you have, the old 6.5 had a frame mounted cylinder shaped 12v pump on the driver side ahead of the tank, but not on an LLY.
 

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Discussion Starter #8
190000 miles.. ran fine friday night. pulled up at home and killed it.. started up sat morning put it in reverse and let my foot off the brake and it died.. then wouldnt do anything but jst keep turning over.. never started.. i assumed there would be a pump jst like a gas..
 

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Well, the bad news is the CP3 at 200K is pretty worn in a lot of cases, so it is possible, but not likely, chances are you would have been seeing p0083 codes coming up if it was dying. How old is your fuel filter? Have you tried to re-prime it yet? Odds are better you have air in the line, could be a cracked WIF on the bottom of the filter, could be the bleeder screw on top of the housing, could be a plugged filter. I would start there, I suspect the primer bulb is soft if you tried it right now. Crack the screw, pump it up until you have good fuel, close the screw and see if it will run. Tomorrow morning check to see if the bulb is firm or not, if it is soft you have a leak, most likely either the bleeder screw or the WIF. Just because a filter does not have a lot of miles on it does not mean it is not plugged if you got some bad fuel.
 

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Also could be as simple as the filter itself needs to be snugged up a bit. Is there any fuel around the side of it?
 

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I'm going to say the filter head needs to be rebuilt or replaced. He's sucking air and more than likely its cracked or one of the o-rings has bit the dust.
 

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I'm not sure where the fuse and relay are located, since I haven't looked. Unless they're being used for something else, then they don't do much. As discussed above, from the factory 2nd Gen Duramax (and 1st and 3rd and maybe a couple of others) definitely don't have an electric pump. Just the CP3 which sucks all the way from the tank, including through the filter.

Realizing the original thread is 8 years old, the OP mentions a "100$ pump that looks similar to fuel filter in looks". This suggests he was really talking about the primer pump in filter head mount. That's about the right price (at discount, not from a dealer). A CP3 (the only other stock pump) is well over $500.

But an after-market lift pump is a really good idea. I added a Kennedy Diesel pump a few years ago.
 

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Thanks I had a scare yesterday, but was probably just a bubble. Rock auto and carparts. Com both show in tank ac delco pumps they say fit my 09. I canceled the order, put my tank back primed it and it started runs fine. But at 198000 I think I better get a lift pump. I’ll look at what you mentioned but, if an in tank pump would do it.............
 

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If some show a pump in the fuel tank, it's for the gassers. I haven't heard of anybody putting a gasser fuel pump in the diesel tank, so I assume there are problems trying to do that. Our old trucks have soft sections of fuel lines that are deteriorating. Sometimes they let a little air in and you lose prime (diesel rarely leaks out). Sometimes they collapse and choke off the fuel supply. Some purists say we should fix our lines. Others of us say put in a low-pressure lift pump to avoid collapsing lines, and if a leak gets bad enough you'll smell and see diesel.

Stock, bubbles happen. Many years ago I had changed the fuel filter, drove a 3000 mile trip. Went 400 miles on the next trip, had wheels up on blocks in a campground to level slide-in camper. Next morning rolled off blocks, started truck, ran about 15 seconds, quit, wouldn't restart. Primed and all was good. A bubble.
 

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Have you heard of a pump that screws in between the line and cooler?
I really appreciate your time. She’s got 198,000 miles and I’m worrying about the ink. Pump.
 

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Nope, sorry. Mostly just the Kennedy low-pressure pump. (You want low pressure.) Some of the powerful pumps cause problems with the return diesel foaming up in the tank.
 

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I've driven through Marfa! Sadly, we didn't have time to stay for the lights. Maybe next time!
 
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