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2005 Silverado 2500 6.6 Duramax starts then dies

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roadkill1938

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Discussion starter · #1 · (Edited)
I have a 2005 Duramax 6.6 with 440K miles on it and it cranked fine but won't run. Replaced fuel filter and primed many, many times. It runs for various times then dies. Obviously it is only running long enough for the fuel in the filter to run out.

I had my friend continue pumping the primer button while I cranked it. The engine ran as long as he pumped the primer. As soon as he stopped, the engine stopped. Is it possible the primer housing has a leak and it is aerating or do you think the FUEL PUMP or INJECTOR PUMP is gone? Other suggestions?

Now that I know it is not the fuel filter, what would be the best thing to check/replace first? How do I even know which one it is?

This is my primary work truck and I need it very badly. I greatly appreciate any advice and experience.

roadkill1938
 
#2 ·
There is no fuel lift pump on these trucks, the main injection pump (the CP3) draws fuel via vacuum directly from the tank. So the slightest crack, damaged seal, or loose connection will prevent the truck from running.

Since it runs as long as you pump the primer, it seems the main injection pump is fine. So here are some of the more common things that have leaked in the past. It is worth checking them all.

  • Cracked/leaking fuel filter. The NAPA/WIX/Fram filters are particularly known for this. If in doubt, get an ACDelco filter.
  • Double gaskets on the fuel filter. If the old gasket stuck on the housing when changing the filter, they can get doubled up, and leak. Make sure there is only one gasket.
  • Loose WIF (water in fuel) sensor or drain. Ensure the drain is fully closed, and the sensor is screwed in to spec (but not over tight, it can crack).
  • Cracked WIF sensor. Can be broken by over-tightening. You can replace it, or buy a block-off plate instead.
  • Cracked or damaged bleeder screw. They are plastic and easy to damage by over-tightening. You can replace it, or upgrade to a metal one (but over-tightening a metal one can crack the filter housing!!).
  • Worn out filter housing or primer seals. You can buy a rebuild kit online, or replace the whole thing.
An "easy" way to find the leak is to pressurize the gas tank. Buy a cheap fuel cap, drill a hole through it, and add an air chuck. Hook up your air compressor, and add a slight amount of pressure to your tank. 2-4 PSI only! That should make any leaks start weeping diesel pretty quickly, then you can fix them.
 
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Discussion starter · #3 ·
Thanks Dave!

A few questions/comments:

- Shouldn't I have seen/smelled diesel leaks if this is happening? This truck has sat and idled for an hour at times in the last 10 days and there was never a leak/puddle. And no leaks in garage.

- The truck sat unused for 6 months until 10 days ago. It started right up at first, but then became difficult to start. I was not aware of the filter pump so I used starting fluid a few times to get her going.

- I have flushed at least 3 tanks of diesel through it in the last 10 days.

Thanks...roadkill1938
 
Discussion starter · #4 ·
I have tried and tried to get this thing running. When I turn the key I do hear a "bumping" noise coming from under the front console. No leaks.

Question...if the fuel FILTER is getting fuel, does that mean the fuel PUMP is working? If so, what could it be after going thru the FILTER?

Thx...roadkill1938
 
#5 ·
As noted above, the CP3 on the front of the engine DRAWS fuel from the tank. The lines and filter assembly are under vacuum when the engine is running. So if there is a leak, it will be air entering the fuel system which kills the engine. That is why, when pumping the primer to pull fuel from the tank, the engine will stay running.

So, stop the air from leaking into the fuel system. Suggestions above are good ones.
 
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#6 ·
Start with the fuel filter head. Seals are probably shot. Biggest thing I have seen that stop these trucks. Check for cracked fuel lines while your there.
 
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Discussion starter · #7 ·
Hooked up a code reader and it gave me the code for a Mass Air Flow sensor. Waiting on it to get here. Is this something that would cause it to shut off after 10-30 seconds?

Also, my air filter had been lived in by a squirrel. It had dug out abut 1/3 of the air filter material as a nest. Got that all out and a new air filter. Now the MAF sensor is my next replacement.
 

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#8 ·
Vacuum it all out. Mass air flow sensor is dirty. Go buy mass air flow cleaner. Take it out. Spray it down. Let it dry and reinstall. Use only mass air flow cleaner. Anything else will leave a film on the sensor and it will throw codes.
 
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Discussion starter · #9 ·
DuramaxEric said:
Vacuum it all out. Mass air flow sensor is dirty. Go buy mass air flow cleaner. Take it out. Spray it down. Let it dry and reinstall. Use only mass air flow cleaner. Anything else will leave a film on the sensor and it will throw codes.
Click to expand...
Yep...did this before buying the sensor. Let it it dry. Nothing. I'm going to try it again.

One new thing...I am now getting a small diesel drip. Still haven't found it, but it is coming from high, as it is running down the oil pan and dripping off of it.

F-ME!!!!!
 
Discussion starter · #10 ·
Ok...here is a summary if anyone can assist.

Truck cranks ONLY if fuel filter is primed then shuts off.

- Replaced fuel filter. $60...No change.

- Cleaned MAF sensor with sensor cleaner. $5...No change.

- Replaced MAF sensor. $145...No F'ing change!!!

- I now see a small puddle of diesel under the truck below the oil pan. Looks like it is dripping from up high but I cannot find the source. Not a huge leak, but I suspect definitely related.

HELP!!!!!
 
#11 ·
Sorry if I missed that you checked all the things listed in Post #2?
- Replacing the fuel filter is one thing, replacing the filter head is probably more important on a truck this old (which I think I would do since you have a problem, instead of rebuilding which I would do if I didn't have your problem). I had to rebuild mine several years ago, as many have also had to do.
- Since there is no lift pump "pushing", then typically there is no sign of a diesel leak. Instead, air goes into the line, which of course makes it die. (With a very small leak, it might continue to run after priming to get it started.) The suggestion above was to slightly pressurize the fuel tank (just a few psi) and see if it shows a leak anywhere. It seems you might have a leak in one of the lines buried in the top of the engine. The lines are very hard to trace, but you gotta do what you gotta do.
- You put a new MAF sensor in. Genuine GM? Sometimes the 3rd party ones are flakey. Did you recheck for codes?
 
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#13 ·
If you have diesel in the valley, then you 100% have a leak somewhere that will cause your problem. The MAF sensor code is a different problem that can be addressed separately. A failed MAF won't cause the truck to die. I would worry about the fuel leak first, then once it starts & idles reliably, you can address the MAF.

You can use the primer to pressurize some of the fuel lines on top of the motor. Pump it up until it gets hard, and go looking for leaks. But that only pressurizes about 1/3 of the fuel lines on top of the motor. As I mentioned before, the best bet is to slightly pressurize the fuel tank, and go looking for the leak. I know it sucks, but that is the easiest way to find it, and it beats throwing parts at it to see what sticks.
 
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#14 ·
replace your fuel filter housing assembly, this happened on mine not long ago, same exact symptoms, was a very small leak but it was from a very small crack in the housing and a little from the worn out primer bulb, took maybe 20-30 min to swap out and fixed it right away. dealer had a few of them in stock, said it was a very common problem.
 
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#15 · (Edited)
Do not buy a filter head from the dealer unless you like spending unnecessary money.

Racor PFF4245R2-02 is direct replacement for LLY filter head. and you get a new filter to boot!

Merchant Auto sells the seal kit to repair your stocker. Dorman also came out with their version -- #904-124
New seals solves the problem most of the time, but will not fix a cracked filter head.

Replace the lines on the engine while youre in there, esp at that mileage. Again, Merchant sells all the proper molded hoses (IIRC there are four), but you can get away with using good diesel-rated fuel line -- just have to route it to account for kinks.
 
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#16 ·
I had this very same problem last week, replace the filter head on Friday and she is up and running again.
 
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