LMM: 1st D-Max

[Kique666]

Hello bought my first duramax about a year ago. It’s a 2007.5 New body style. LMM. Bought it with the EGR delete and DPF also. The exhaust is AFE. I just put bilstein 5100 shocks and some OEM 20” on 285/55/20.
I don’t know much about mechanics but I do want a fair priced build. Engine wise the only problems I’ve had since literal day one is the fuel rail pressure. The day I bought it driving down from Houston to Yorktown i broke down had a reduced engine power and couldn’t move it. Turns out I had a fuel rail leak. After replacing since I’ve had multiple occasions of the reduced power on the dash. Only during towing and being excessive on the pedal. I’ve seen most people are going with the high pressure fuel pump. Wondering if they’ll solve my problem? Also my tips on what my next purchase should be? I want to be able to get on it with no worries and tow anyone across state line . If I woke my way up on the performance stages where should I start?
Also been thinking about doing dually conversion. Already have the bed.. don’t know the process and if it’s worth the hassle. Any thoughts?

 

[ikeG]

In my experience on an LMM, low rail pressure problems are from injectors returning too much fuel. Shows up when towing frequently. How many miles on the truck?

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[zakkb787]

Need to do a return test on the injectors and hook to a scan tool to see what your actual vs desired rail pressure is.

If you want to get on it making decent power and tow across the states, build your trans

 

[WVRigrat05]

Is it a stock hp tune with deletes or a bigger tune? Truck have a lift pump? If it has no lift pump and a larger tune with a older fuel filter it will limp due to lack of fuel.

If it's a small tune and filter is good then most likely injectors are returning too much fuel.

 

[Kique666]

164,xxx Miles. As far as I know it’s just tuned for the delete but not sure and don’t know how to check that. It doesn’t have lift pump. After taking it to the performance they said i would need a lift pump.
How do I see how much pressure is actually getting pushed? Would and EGT monitor show that? If so been looking into a few different ones I really like the CTS2 Insight? Any Recommendations?

 

[TheBac]

Moved this over to LMM section as you're asking a lot of tech questions.


A lift pump like Kennedy, AirDog or Fass is never going to hurt, but you should take Ike's advice and get the injectors tested first. You need to do a return rate test on them to see where thats at. A lift pump may crutch slightly bad injectors, but it cant make up for really bad ones.



As to the monitor, look over in the Tuning/Gauges section for info on those.

 

[Kique666]

Moved this over to LMM section as you're asking a lot of tech questions.


A lift pump like Kennedy, AirDog or Fass is never going to hurt, but you should take Ike's advice and get the injectors tested first. You need to do a return rate test on them to see where thats at. A lift pump may crutch slightly bad injectors, but it cant make up for really bad ones.



As to the monitor, look over in the Tuning/Gauges section for info on those.

Thank you for the help and I will look into the injectors and the gauge section

 

[Burn Down]

Never hurts to ck injector health on a new to you vehicle. But I would look closely at the fuel lines at the left rear top of the engine. I have diagnosed 3-4 lmm's with kinked fuel lines in that location. When the engine torques over it kinks the line even worse.

https://www.duramaxdiesels.com/forum/showthread.php?t=56508

 

[Kique666]

In my experience on an LMM, low rail pressure problems are from injectors returning too much fuel. Shows up when towing frequently. How many miles on the truck?

Sent from my SM-G960U using Tapatalk

166,149
So it seems I need to definitely take it in almendre and see what my actual return is vs my desired and see if that needs to be changed. By any chance anyone from the RGV and have recommendations?

 

[NC-smokinlmm]

Google bottle test LMM duramax, could be as easy as shimming your fprv...

 

[Kique666]

Hello Everyone update to my truck. As a gift from my wife I was bought a tune, EFI Live w/ on the fly switch. I haven’t had any problems with my fuel rail pressure. It’s been two weeks and on 800 mile trip. It has towed. It has raced a little on the freeway. I did throw another engine code for my #6 glow plug. That was replaced today. Other than all I’m throwing is codes for my ABS which will be looked at this upcoming week.
Now that my fuel rail pressure seems to be fine. Next I want to look into cold air intake and cool and hit side pipes. Is there any thread anyone can recommend me to? Or any experience with Wherli Customs? I’m leaning towards them but I don’t see any specifications on any websites like I do other products but I have seen happy customers on YouTube and it looks real nice! Thanks in a advance!!

 

[TheBac]

You do not need either of those on a stock truck. Just keep a good filter in the stock box.

What lift pump did you end up installing? If you didnt buy one, then thats your next mod.

 

[Dozerboy]

Tom is right

Here is a thread on some dyno results on common bolt ons.

https://r.tapatalk.com/shareLink/to...6&share_fid=8839&share_type=t&link_source=app

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[Kique666]

Hello everyone. Well I went ahead and spoiled myself and bought the WCFAB Intake and Air Horn (did that before looking back on the thread). Before that though I actually did find out I already have a lift pump just not one with the filters (I’ll be adding an image). I haven’t been able to find it on the internet nor have I got in contact with them thru their line yet. But if anyone has any info on it it’s D-Max series. SN: 3953. Just looking to see if it’s strong enough to not have to upgrade it.
I had an unexpected trip to pick up my broken down parents in Van Horn, Tx. I traveled from Weslaco, Tx. Trip ended up being 1615 miles, used 102.8 Gal, 15.2 MPG, 70 AVG Speed. I towed 3,956lbs on the way there and 3653lbs on the way back. I will say “Miranda” felt amazing. Transmission temp never went higher than 163. Coolant temperature stayed just over 200. I ran her on 2 tow mode w/tow haul the whole way. I can’t tell you how happy I am with how she ran. Got up on it a few times uphill and she ate it up to 95 no problem.
She was a lil hard to keep straight for my front end definitely needs works. I want to go with Kryptonite’s front end package anyone have any personal experience with it?
After that info, jw still if y’all would think I need to upgrade the fuel system or maybe this one is fine at what I’m pushing (stock lol). As far as any problems I’ve had in the past traveling on the 10 the tune and the work on my fuel rail has seemed to solve it.

 

[torqued2dmax]

Do you know if the trans has been rebuilt ? If not , be careful not to use more than a mild tow tune in 5th and 6th when you jump on it , or you will start to limp it and then a $5000 rebuild will be next on your list .

 

[Kique666]

I’m not sure that it has or hasn’t. I’ve been talking to a mechanic to go thru the whole truck and see what looks like it need to be done but it’s going to cost a lot more than I thought so idk if I am. Would anyone recommend that I should though?
Update on the lift pump: I got ahold of Fass today and got the specifications on mine it is pushing 80-90GPH at 8-10 PSI.
Would anyone recommend I still need to upgrade anytime soon on the fuel pump or should I be good with that. If so roughly till what hp/tq do y’all think that would be good till?

 

[torqued2dmax]

Keep all your fluids and filters changed , grease all fittings regularly and live happily ever after still married ! And only run tow tunes , unless you are prepared to pay $5000 for a trany. If $ is no object or you can write off the parts like many of us on this site because of business expenses , then the sky is the limit !