engine bogs under heavyload

[bobconst]

Ihave a 2004 dura max and when I acclerate heavy especially pulling trailer going uphill or passing the engine bogs down . under normal conditions it runs o.k. it's not the tranny aamco says its afuel/exhaust restriction anybody else have/had this problem? engine has about 130,000miles

[Mark Rinker]

1) Air filter restricted?
2) Fuel filter restricted?
3) Exhaust restriction?

Q1) Is there black smoke present during the bogging, or no smoke at all?

[bobconst]

doesn't smoke replaced air filter it is a 2004 gmc 2500hd crewcab doesn't tow much basically bobcats and construction equipment etc going to try fuel filter this is the company truck and it gets operated alot when the fuel gauge says empty think it could be settlement from bottom of tank?

[Mark Rinker]

Fuel filter should do it. Don't wait, if its that bad, you are probably passing fine particulates through and the injectors will be next.

Q2) Does it smoke at idle?


Follow all of this up with regular use of a good diesel additive like FPPF Total Power. If its been awhile - or never - double up the strength for the first two or three tanks. That will help to remove deposits and give the truck back some of its original pulling power.

[bobconst]

First off thank you for your input mark greatly appreciated haven't put fuel filter on yet but did put in air filter seems to help . dealership done some work fuel or injection pump was installed about a month ago this gets about 14.5 mpg at 70-75 mph does this seem reasonable or can it do better ?

[bobconst]

doesn't smoke a idle forgot to answer question

[Mark Rinker]

You're welcome. Its fun to troubleshoot OTHER peoples rigs... :) Check your paperwork from the dealer. If they did fuel related work, they almost certainly did the fuel filter. Was it always weak towing, even after the dealer work, or did it just set in?

Try running a few tanks of additive through, and when on a long trip, set your cruise at 1800 rpm (peak torque) and accept whatever ground speed you get.

You should get about 18mpg unloaded. Braking and acceleration habits can make it as high as 20, as low as 16, even running at peak torque. Every ~1,000 rpm after 1800 costs you about 1mpg.

[EdHale]

I just finished a 200 miles run down the interstate at 75-78 mph with a/c and not towing. Computer shows 18.3 mpg, but it is consistently 1-1.5 low. I'm pleased. 27,000 total miles. Ed

[bobconst]

it just started acting up but seems to be running ok now I'lltry using the additives like you said . this truck usually runs between nashville tn -bloominton ill 423.15 miles 1-2 times amonth takes about 32.5gal one way with trailer alittle less without trailer . according to my math thats only 13.02 mpg defenitely can do way better

[Mark Rinker]

Verify dealership installed fresh fuel filter, replace if not certain or over 15K miles;
Run additive heavy to clean injectors;
Possible partially clogged catQ3) Is this '04 equipped with an LB7 or LLY Duramax? What is the 8th digit in your VIN number?