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Duramax guys?

max 02

max 02

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Question for you guys. My 02 has been giving me some trouble. Starts fine when it’s cold. Problem is after it’s warm it has long cranking times before it starts.
I have searched all over for a week on the internet. There is so many things that could be going on from a fuel line sucking air, leak at the filter head, failing cp3, and high return rates.

Runs great, no fuel in the oil, no visible leaks, balence rates good. Injectors are 150 klms since replaced howe’s in every tank.
I have no lift pump.

I’ve tried to pressurize the fuel tank to look for any leaks, but I couldn’t get it to pressure up.

No easy way to check on return rates... might have to take it to a shop.

Wondering if any of you guys have had similar problems?

@Russell

@jekquistk5 why did you put a fass system on your old truck? And I remember you replaced all your fuel lines, injectors. Not sure if you did it all at the same time or not?
 
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I'm afraid that I won't be of much help other than to maybe add some information to hopefully help.

My truck is a an 01 LB7 CCSB. Bought it with about 315,000 miles. Has 394,000 miles or so now.

Was smoking when I bought it due to the injectors leaking. I just did injectors last month. Ran fine up until the last week before the injector swap when they started dropping out. Did have a rough/loping idle at times. Injectors seem to have fixed it .

It may have had the issue of long cranking when hot, but can't swear to that.

As far as the fuel system leaks, I have had one. The priming pump in the filter housing developed a leak. When it did this, it wouldn't start. If I primed it, it would fire, then stall, and would need primed again. Rebuilt the pump and good ever since.

As far as lift pump. I do not have one installed. I have one here, waiting to go on. It's an Air Dog 150, I believe.

Most other diesels have a lift pump stock. For whatever reason, Chevy didn't put one on the lb7 but the system works. The concerns are with the CP3 (ceramic, 3 piston injection pump). If the pump is run dry (no fuel in the tank, air leak in the fuel line, etc.) it can damage the pump. This can lead to failure or premature wear. If the pump is damaged or worn out, it can't provide enough presure to supply the injectors leading to poor performance.

I am going to install the pump to try to avoid the possible damage of a dry run, and, with the high mileage of my truck, I figure that getting a boost in flow couldn't hurt. If my pump is weak from wear, etc, I figure it might help.

I don't know if any of my rambling was of any help, but there it is.
 
eric67camino said:
I'm afraid that I won't be of much help other than to maybe add some information to hopefully help.

My truck is a an 01 LB7 CCSB. Bought it with about 315,000 miles. Has 394,000 miles or so now.

Was smoking when I bought it due to the injectors leaking. I just did injectors last month. Ran fine up until the last week before the injector swap when they started dropping out. Did have a rough/loping idle at times. Injectors seem to have fixed it .

It may have had the issue of long cranking when hot, but can't swear to that.

As far as the fuel system leaks, I have had one. The priming pump in the filter housing developed a leak. When it did this, it wouldn't start. If I primed it, it would fire, then stall, and would need primed again. Rebuilt the pump and good ever since.

As far as lift pump. I do not have one installed. I have one here, waiting to go on. It's an Air Dog 150, I believe.

Most other diesels have a lift pump stock. For whatever reason, Chevy didn't put one on the lb7 but the system works. The concerns are with the CP3 (ceramic, 3 piston injection pump). If the pump is run dry (no fuel in the tank, air leak in the fuel line, etc.) it can damage the pump. This can lead to failure or premature wear. If the pump is damaged or worn out, it can't provide enough presure to supply the injectors leading to poor performance.

I am going to install the pump to try to avoid the possible damage of a dry run, and, with the high mileage of my truck, I figure that getting a boost in flow couldn't hurt. If my pump is weak from wear, etc, I figure it might help.

I don't know if any of my rambling was of any help, but there it is.
Click to expand...

Thanks. I was thinking any lift pump would help me out. I just don’t want to buy a Fass or Airdog and then it still needs a injector. I got no problem changing them myself except for the cost. And I don’t want to be guessing.

Did your filter housing have a visible leak? Mine doesn’t. The engine always starts without priming at times normal and at times long cranking.
 
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I don't remember a visible leak initially. It just fired and died, then was just cranking, not starting. I don't remember seeing anything, but I primed the filter, and then there was a visible leak at the priming pump.

If there is a small leak, the fuel in the line could be draining back towards the tank. If that's the case, you would have to crank for a bit to get it drawn back up to let it start. You might try hand priming the filter every time you start it for a while and see if that eliminates the long cranking.

If it has a leak, a lift pump may also show you where. It would pressurize the line, forcing fuel out and causing a wet spot, as opposed to the current situation where it's drawing air in. Kind of an expensive way to find it, but I believe a pump is a good idea even on truck with no issues. I would hand prime it for a while to check first.
 
eric67camino said:
I don't remember a visible leak initially. It just fired and died, then was just cranking, not starting. I don't remember seeing anything, but I primed the filter, and then there was a visible leak at the priming pump.

If there is a small leak, the fuel in the line could be draining back towards the tank. If that's the case, you would have to crank for a bit to get it drawn back up to let it start. You might try hand priming the filter every time you start it for a while and see if that eliminates the long cranking.

If it has a leak, a lift pump may also show you where. It would pressurize the line, forcing fuel out and causing a wet spot, as opposed to the current situation where it's drawing air in. Kind of an expensive way to find it, but I believe a pump is a good idea even on truck with no issues. I would hand prime it for a while to check first.
Click to expand...

Yeah i can pump the primer till it is hard and there is no leak I can see. Holds prime for a minute, that I timed this afternoon before work. The lift pump would definitely help me find any leaks. And it has been something I wanted to add for years, just never had any trouble with the stock system so I didn’t worry about it.
Fastereddie said:
Just my opinion but, you should have a fass/airdog
anyways. It removes entrained air, better filtration, and keeps your pump from starving. And when you change filters, it’s a snap to bleed.
Click to expand...

Yup very true. It might be in my future soon!
 
Like I said, I believe that the pump is a good idea on even stock and fully functional trucks. I have wanted to put one on mine for some time, but like you, the truck was working fine as is. Just waiting on a couple of good days to be able to install it.

I ordered mine when I replaced the injectors. Got them from Lincoln Diesel Specialties. They had a combo package of injectors and pump for about the same money as buying the injectors alone locally. And a much lower core charge, too.
 
I replaced all the feed lines because the factory braided line collapses when used with a cp3 without a lift pump. The CP3 suctions from the tank, soft line overtime it closes. There was a factory TSB about the line specifically behind the driver side valve cover. It looks fine due to the stainless braid, but the rubber on the inside is collapsed. I'll see if I can find the pictures I took. Add a lift pump this isn't an issue. I will be adding a fass or airdog to my truck soon.

Edit: When did lift pumps get so effing expensive.
 
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A lift pump may not fix the issue you are having now , but every modern common rail diesel should have a FASS system . ( AirDog ......have seen lots of premature failures in the past not sure if it’s still an issue with them or not) .

We installed FASS systems on our large trucks and even some of the Heavy Equipment in the oil field , and I have one on every diesel I own that I plan to keep.

Hot restart issue to me sounds like maybe your CP3 is getting weak . I would get a scan tool and see what your Actual rail pressure and commanded rail pressures are at cranking.
 
jekquistk5 said:
I replaced all the feed lines because the factory braided line collapses when used with a cp3 without a lift pump. The CP3 suctions from the tank, soft line overtime it closes. There was a factory TSB about the line specifically behind the driver side valve cover. It looks fine due to the stainless braid, but the rubber on the inside is collapsed. I'll see if I can find the pictures I took. Add a lift pump this isn't an issue. I will be adding a fass or airdog to my truck soon.

Edit: When did lift pumps get so effing expensive.
Click to expand...
They are not cheep. Hard to find a good used one too!

76zimmer said:
Has anybody tried the Kennedy pump? Sounds like it recommended on DP.

http://www.kennedydiesel.com/detail.cfm?ID=399
Click to expand...

Price is good on those and I hear lots of recommendations for them to. I think the reason guys go with Fass or Air dog is the extra fuel and water separator is all in one ready to go.
Plus for the Fass A/D is they are easy to get to for service. Minus would be guy could damage one or have some asshole fock with it because they are easy to get to.

yellowK20 said:
A lift pump may not fix the issue you are having now , but every modern common rail diesel should have a FASS system . ( AirDog ......have seen lots of premature failures in the past not sure if it’s still an issue with them or not) .

We installed FASS systems on our large trucks and even some of the Heavy Equipment in the oil field , and I have one on every diesel I own that I plan to keep.

Hot restart issue to me sounds like maybe your CP3 is getting weak . I would get a scan tool and see what your Actual rail pressure and commanded rail pressures are at cranking.
Click to expand...
Agreed. I`ll get it looked at with a teck11.
 
Hopefully its an easier install on the LB7's than it is on an LML. Have to drill holes in the fuel pump module, modify the sender etc. Hence why I'm waiting, my truck is still under warranty.
 
jekquistk5 said:
Hopefully its an easier install on the LB7's than it is on an LML. Have to drill holes in the fuel pump module, modify the sender etc. Hence why I'm waiting, my truck is still under warranty.
Click to expand...


After all the work you’ve done to the blazer that should be a nice little side project for you, plus you have a nice shop and hoist! :waytogo:
 
Last night my wife said... my opinion with the truck something happened to the fuel lines when the transmission got taken out. Probably a line is pinched. It was totally fine before.

Hope she’s right! Just gotta find it. I changed the fuel filter yesterday and after I shut the truck off I could hear a hiss comming from the back of the engine. Never remember hearing that before.
 
max 02 said:
Last night my wife said... my opinion with the truck something happened to the fuel lines when the transmission got taken out. Probably a line is pinched. It was totally fine before.

Hope she’s right! Just gotta find it. I changed the fuel filter yesterday and after I shut the truck off I could hear a hiss comming from the back of the engine. Never remember hearing that before.
Click to expand...
Could it be that the lines got shifted somehow and the push connect fitting is leaking?
Or they got tweaked when the transmission was out? I am just going off of what I saw when we did injectors on my son's '03.
I had told him to get a lift pump before he even bought a D-max. I had heard of too many problems caused by low fuel pressure to the CP3 as well as Dodge trucks having problems without a good supply of fuel.
His truck started very quickly and smooth after we changed injectors and fuel lines with the FASS pump.
 
Couldn’t find anything close to a leak under the truck for a fuel leak. I took the line off the primmer pump that goes to the engine, put my thumb over the port and pumped it up. Built tons of pressure and held. I’m thinking everything is good from the primmer pump back to the tank.
 
Replace all rubber/rubber lined fuel hoses. They have issues with the lines coming apart like was previously said and also issues with them kinking and becoming a restriction. Also rebuild or eliminate your factory fuel filter head. They suck air. An aftermarket filter/pump setup will get rid of it or you can build your own. I like the Fleetguad filter head but Napa and other do them also. You can get a fitting and put two of them together and run an FS1000/1001 as a water separator and then a Cat 1R-0749 as your main 2 micron filter. I like the Carter P4601HP pump. I know Napa sells one just like it too. https://www.summitracing.com/parts/crt-p4601hp/overview/
https://www.duramaxforum.com/forum/diy-tech-discussion/63780-found-fix-p0087-when-under-load.html
https://www.dieselplace.com/forum/7...430062-collapsed-kinked-fuel-line-repair.html
 
Truckman4life said:
Replace all rubber/rubber lined fuel hoses. They have issues with the lines coming apart like was previously said and also issues with them kinking and becoming a restriction. Also rebuild or eliminate your factory fuel filter head. They suck air. An aftermarket filter/pump setup will get rid of it or you can build your own. I like the Fleetguad filter head but Napa and other do them also. You can get a fitting and put two of them together and run an FS1000/1001 as a water separator and then a Cat 1R-0749 as your main 2 micron filter. I like the Carter P4601HP pump. I know Napa sells one just like it too. https://www.summitracing.com/parts/crt-p4601hp/overview/
https://www.duramaxforum.com/forum/diy-tech-discussion/63780-found-fix-p0087-when-under-load.html
https://www.dieselplace.com/forum/7...430062-collapsed-kinked-fuel-line-repair.html
Click to expand...

Thanks Luke!
Good reading in those links.

I replaced to two lines from the filter head. Seemed to help a bit. The truck starts like a champ right now. The temp outside got way cooler again so that helps keep the fuel cold. Started like shit when it was warmer.
Still have to test with a teck 11 I haven’t had a chance to get that done yet. Also found a simple return rate test to see if the injectors are happy or not. Again haven’t had time to play with it much. I’ll do get those tests done before I replace anything else.
At least I know the balance rates are fine #8 is a bit out but in spec, no fuel in the oil or smoke out the exhaust.

EF71CEC3-F577-4C9B-8298-326D3DE9EAF9.jpeg
 
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