Duramax LMM problems! Help please! [Archive] - Duramax Diesels Forum

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Bryan Burt
09-11-2013, 10:24 AM
I've got a stock lmm 2008 crew cab 4x4 duramax 273k miles on it that is showing low fuel rail pressure and also lots of black smoke when you get on it and I figured a lift pump might help the cp3 pump easier making the fuel rail pressure better since it has the mileage on it. I was going to install a ppe shim kit also on the fuel pressure regulator valve.

The injectors seem pretty loud also at normal driving speed especially around 1000-1500 rpms. Like maybe a fuel knock? The oil pressure stays steady at 26-30 psi at idle and 45-50 and 2000 rpms. So I don't think it's an engine knock.

I took it to get checked out for $100.... and the guy said the injectors sound a little loud and his computer showed ok balance rates. His gauge showed 5000psi on the fuel rail also? Is that good? He said it most likely is injector varnish build up and he can run the truck on his special cleaning chemical he mixed for another $100 that would most likely clear it it?

I changed the fuel filter about three times now. And each time i poor diesel clean stuff in the filter to clean the injectors, but no change yet. Still says to replace the filter every time I get on it right after I replace the filter. Fuel mileage seems to be pretty poor also. Just wonder if yall might shed some light on the subject.
Thanks
Bryan.

RPM Motorsports
09-11-2013, 10:38 AM
Water in tank? Did you just fill up when it started, or has it been a slow oncoming process? Did he ramp up the CP3 to see what he can get max rail to?

03Tommy
09-11-2013, 10:40 AM
I had the same issues when I was running a PPE programmer. I put on a lift pump, put a race valve in the rail and still nothing but problems. I have switched to EFI and dont have the issues anymore. I do go through fuel filters quite a bit though still. Oh and my truck has 204k.

Ron Nielson
09-11-2013, 11:07 AM
I took it to get checked out for $100.... and the guy said the injectors sound a little loud and his computer showed ok balance rates. His gauge showed 5000psi on the fuel rail also? Is that good? He said it most likely is injector varnish build up and he can run the truck on his special cleaning chemical he mixed for another $100 that would most likely clear it it?


If the Chemical process is from TERRACLEAN, I think the price for a cleanup just may be worth it. See here:TERRACLEAN (http://www.pistonheads.com/gassing/topic.asp?t=1146760)

There are at least some people that feel the product is quite worthwhile. Also look on Youtube for TERRACLEAN demonstrations. Nothing like a guy in a lab coat doing a demonstration to sell a product.

Bryan Burt
09-11-2013, 02:13 PM
Water in tank? Did you just fill up when it started, or has it been a slow oncoming process? Did he ramp up the CP3 to see what he can get max rail to?

I also took the bed off and opened the fuel tank and saw no water. There was some small pieces of debris in the bottom that I cleaned out. He did reve up the engine to test cp3 pump and said it was normal.

As far as if its a slow oncoming process... I have always had 7.3L ford f250s and really didn't know what duramaxs sounded like normal. I test drove it and got on it and all seemed well so I bought it and on the way home the problem happened only at WOT. It will only happen at wide open throttle. It has great power just black smoke very thick and will go into limp mode if I get on it. It black smokes accelerating normal and some days it will black smoke a little at idle. So I have know clue with this may have started.

I paid $12000 for it. I figured that was a steal. Was that a good price even if I have to put in an all new fuel system in. I can do all the fuel system on my own for around 4800. That's new 75hp Bosch injectors and an cp3 with fprv.

Btw. Thanks again for y'all's time. I'm new to the duramax world, but I feel that if someone else can do it then I can too and will.

Bryan Burt
09-11-2013, 02:16 PM
If the Chemical process is from TERRACLEAN, I think the price for a cleanup just may be worth it. See here:TERRACLEAN (http://www.pistonheads.com/gassing/topic.asp?t=1146760)

There are at least some people that feel the product is quite worthwhile. Also look on Youtube for TERRACLEAN demonstrations. Nothing like a guy in a lab coat doing a demonstration to sell a product.

I probably will try that too. That sounds like the cheapest possible alternative, but it would give me a better piece of mind to replace all the fuel system.

02greysixer
09-11-2013, 02:55 PM
You sure it's totally stock tuning? It may have some kind of terrible tune in it you are unaware of our the p.o. didn't want to admit to having in it. If I were you I'd get someone with efi or a dealer to read it and reflash it if anything seems off. You may just solve all your issues by erasing somebody's hack job tuning and starting over

sent from a galaxy far far away

Bryan Burt
09-11-2013, 11:31 PM
You sure it's totally stock tuning? It may have some kind of terrible tune in it you are unaware of our the p.o. didn't want to admit to having in it. If I were you I'd get someone with efi or a dealer to read it and reflash it if anything seems off. You may just solve all your issues by erasing somebody's hack job tuning and starting over

sent from a galaxy far far away

That could most definitely be it. I figured when the guy with the high tech computer would be able to tell me, but he did seem sure if it was a stock tune or other. I might get the dealership to check it out then. I wonder how much that is ha ha. Seems like everything is $100. Lol.

I also installed the ppe shim kit in the fuel pressure regulator valve today and I have noticed a for sure throttle response change and maybe a little power gain. I could be wrong tho, but definitely seems to have better throttle response and start off and interstate speeds when climbing the hills. I reset the truck and the fuel filter still went to 0% life even at idle this time.

Texas Chevy
09-12-2013, 06:02 AM
Throw a quart of two storke in the tank see if it will quiet down the injectors. Get the dealer to flash it bak to stock and go from there.

Philtopgun
09-12-2013, 07:15 PM
I was thinking ur cp3 is weak, but sounds like u checked it on the laptop....

Bryan Burt
09-15-2013, 11:06 AM
I was thinking ur cp3 is weak, but sounds like u checked it on the laptop....

Ye the diesel mechanic said the cp3 was fine. Maybe my injectors are returning to much fuel? I tried the lift pump and nothing changed. I adjusted it to 7psi.

Bryan Burt
10-16-2013, 06:00 PM
I put diesel kleen in it over and over and the injectors got quiet. The low fuel rail and limp mode problem was collapsing fuel lines. So I bought 4 feet of 100r16 hydraulic hose and replaced all rubber lines. Two hoses at the fuel filter, 1 hose by the transmission, and one hose by the brake master cylinder. After I did, my 273k mile LMM will fly no problems. I'm so excited it wasn't injectors or injector pump. I removed the lift pump also. It's all factory now. The black smoking is the DPF. It's worn or cracked. From what I understand it will not hurt anything to drive like that. I'm going to be deleting the dpf here shortly anyways. :thumb: