Bogging down during start up and sometimes during driving

Doonatic · May 23, 2018

Hey guys, I need some help.

Recently my only vehicle, an 03 2500hd 6.0 4x4 started to hesitate during start up. It bogs down as if it sounds like it is not getting any fuel when i step on the gas. Instead of revving up, it sounds as if it is choking on too much air, and no fuel. I changed the oil, filter, and air, and filled with gas from one of the two gas stations I always fill at. I have owned this truck most if its life, 11 yrs and 180k+ miles on her. When it started doing it the temperature outside was about 45-48 degrees, and I was coming off a graveyard shift. At the same time, it was choking and struggling to stay running, the computer (dash gauges and info center) also started freaking out and throwing messages “change engine oil” and “oil life reset” and “loss of engine power”. Once it quit, the distance to empty now was not reading the same as it was when i shut it off at midnight. In fact about 70 miles less, and the gauge still said full. Once it was “stable” to drive home, on one of the hills i was climbing, clearly the motor was loosing power, tranny wasnt downshifting, and loosing speed quickly, and some hesitation. However at the top of the hill, it ran just fine.

Fast forward a day, started fine, ran fine. Next day, changed some bushings on the lift, drove into town just fine. When I left the store, started just fine, backed out and started to to proceed to the exit, and it started hesitating again. Cleared up after about 10 seconds, then on my merry way again. Got to the house, luckily, and it started the whole cycle over again. Throttle response was all but gone, sounded as if it was bogging or flooding the motor with air, but under idle struggling to stay at running, and choking, rpms are below 500 when it does it. Once I get the motor to stabilize with the feathering if the throttle, i can put my foot into it and it revs just fine. Computer still shows 187 mi to empty, when it was 265.

The things I have done to this truck since I have owned it are, new (used) transfer case, new front end ( multiple times) , new (reman) dash gauge cluster, change plugs, water pump, k and n, batteries, window regulators, new climate control unit.

I hope you guys can help, before having to ATTEMPT to take it anywhere.

Formulabruce · May 23, 2018

Start simple. Remove the air box at the throttle and CLEAN the throttle and BOTH sides of the plate extensively with Throttle body cleaner ( NOT CARB CLEANER) Clean it well. it may look clean, but it needs a cleaning. Then remove the BCM ground on the body mount below drivers door, CLEAN the wires well, if brown, you'll need to solder on new ends, clean frame and re install, and put on some waterproof ( marine) grease.

Both of these should help a bunch.

Supreme Pizza · May 24, 2018

Diagnostic shop. Call around and feel them out. Try to find a shop that wants to help as opposed to a money mill. Could be any number of things. Surely you are getting OBD2 codes by now? What codes are you getting?

Doonatic · May 24, 2018

Starman, no codes. If there are codes, I dont have a unit to detect them. However no check engine either.

Supreme Pizza · May 24, 2018

Solid codes will turn the check engine light on.

Pending codes will not.

Most auto parts stores will scan your computer for codes for free.

https://www.amazon.com/Autel-MaxiScan-MS300-Diagnostic-Vehicles/dp/B001LHVOVK/ref=sr_1_44?s=automotive&ie=UTF8&qid=1527163005&sr=1-44&keywords=obd2+scanner

Doonatic · May 25, 2018

Update: So after testing fuel pressure, draining a full tank of gas via hand pump, dropping the tank and replacing the pump (also had to change the electrical connection), cleaning the throttle body and air cleaner assembly, the truck RUNS fine. However when I started it back up to test run, the lights are now all jacked up.

Hazards only come on and dont flash, when lights are on or off. When lights are on, and brake is applied, the tail lights go out but the brake lights come on, and so does the third brake and the turn signal lights in the mirrors and the license plate lights go out, and so does the side marker lights.

At the same time the computer is not reading the distance to empty, correctly-still. It still shows abt 70 miles off, with th a full tank on the gague. With that, I am convinced it is a bad gauge cluster again.

silveradosid · May 25, 2018

you still have ground problem some where for the lights

Supreme Pizza · May 25, 2018

I doubt that it will help, but you could try resetting the computer - by disconnecting the negative battery cable for 30 minutes. \

I would check the various ground cables throughout the rig. When you put the fuel tank back in, did you crush and electrical wires between the tank and the vehicle?

Doonatic · May 25, 2018

5 hours ago, starman8tdc said:

I doubt that it will help, but you could try resetting the computer - by disconnecting the negative battery cable for 30 minutes. \

I would check the various ground cables throughout the rig. When you put the fuel tank back in, did you crush and electrical wires between the tank and the vehicle?

Starman, i have been praying that i didnt. However i did clean the grounds under the door.

davester · May 26, 2018

That's just for the ABS computer. There's a bunch all over the truck...

Doonatic · July 6, 2018

so turns out it was the fuel pump. 26 gallons of gas to siphon out, then I was able to drop the tank and replace the pump. I had to test the fuel pressure first. Gauge was reading 32 lbs., every time the engine was bumped. It should be 50-62 lbs. I didn't even notice that classic Chevrolet fuel pump whine. Normally that is a dead giveaway, to a bad pump. However, not bad lifespan for a fuel pump in a truck with 220+k on it.