[frankthehammer]

Hey folks, i have been poking around for a while and while we all seem to have the regular issues with our trucks i have a new one that is causing me some grief. Whenever i have come up to speed i feel a intermittent loss of power, not complete loss of power, but like i am driving two footed and am lightly applying the brake for a split second. it is very noticeable at highway speeds since it is easier to maintain 70mph than say 35 so i really notice on the highway. i have no idea what it might be any ideas?

2003 Chevy 2500hd 6.0l gas 4x4 ,240,000 miles original brakes!

 

[silveradotrailblazer]

Welcome to the club. Is the check engine light on??

 

[frankthehammer]

no, does not give me any problems other than noticeable kind of surging feeling, but it is like an anti-surge about every 10-15 seconds. the only trouble i have had out of this truck is the typical instrument cluster replacement, a water pump, a wheel bearing, and i had to have the transfer case replaced this past winter. i did have the p1516a code come up from time to time, but i cleaned the throttle body and that seems to have corrected that issue since it has not happened in the past two months. Prior to the cleaning i could pretty much make the reduced engine power / p1516a code happen at will if I didn't continually vary the pressure on the gas pedal.

 

[stephan]

Welcome to the club Frank. Have you checked the fuel pressure when it's doing this surge? Low fuel press will tend to make them surge due to a lean condition, rather than a flat out miss like a plug or wire would. You might also check for a vacuum leak which will also lean it out.

 

[frankthehammer]

Thanks for the info. No i have not checked the fuel pressure or vacuum lines. I have no idea where to start on this. I will have to start looking into this a little further. I did check the codes last night and have found two codes - 0035 left front wheel speed sensor, and 0055 vehicle speed sensor circuit, so I am thinking that maybe there might be some issue between the speed sensor readings causing some issue with the tac module. I will see if i can borrow a fuel pressure guage from one of the box auto stores and check that as well.

 

[frankthehammer]

update - so i checked the fuel pressure, 52-53 psi static, key on engine not running, and while running i get 49 psi, all this with brand new fuel filter so no clogged fuel filter. i also pulled the vacuum line from the fuel pressure regulator and no sign of fuel in the vacuum line to suggest the fuel pressure regulator is bad. I am thinking i am going to be putting a fuel pump in from what i have discovered. i also am noticing the surging is more apparent now when i first start the vehicle in the morning and once it has been driven a few mile it is not as bad. I am looking at ordering a fuel pump from Rockauto but they have several to choose from - i am leaning towards either the ac/delco or the bosch brand as the review for the airtex have not been so good. anyone have any experience to share on how to attack this?