Sputters while driving and lopes at idle

[625fireman]

Demographics: tell us about your truck and your ambient conditions:

- Year: _1994_____
- Truck model and class (ie: c2500) __k 3500 4x4_______
- Automatic or Standard __was auto now 5sp________
- Mileage: (indicate miles or km) _83352________
- Replaced parts and mods (IP, PMD, chip/PCM, TM, injectors etc) __pmd w/cooler on intake __new heads lift pump
- Model: ‘S’ or ‘F’ engine, NA or Turbo, EGR? _F_____________
- Ambient outside temp: (indicate *C or *F) __dosen't matter________
- What fuel are you using? (#1 Diesel, #2 Diesel, Bio, VO, WVO, etc) __#2_______
- What fuel additives are you using? __none_________
- Where are you located? ___NE Ohio__________

General maintenance: inspect and evaluate the condition of each. When were they last changed?
- Air filter __fall 2007_______
- Fuel filter __spring 2008_______
- CDR Valve? _____nope____
- Coolant – last flushed/replaced at _fall 2007____________
- Oil – synthetic/regular, changed at __83000_________
- Batteries – state of charge, (matched set) replaced at __full/ fall 2007___________
- Battery cables and grounds (removed, cleaned and tightened): __12/13/2008____________

History: (Describe how the problem first appeared.)
- What were you doing when it happened? _inconsisitance_____________
- How was the truck running fine before this problem appeared? ___yes__________
- Has this problem ever happened before? ___yes____________________
- Describe any related factors that might be part of the problem. __left jumper in dtc link while started truck summer 2007____________
- Have you checked for DTC (Diagnostic Trouble Codes)? And? ____yes and none____


Diagnostics:

1] Starting:
1a] Does the engine start? __yes_______
1b] Does the engine crank over? __yes______
1c] Are your batteries fully charged? __yes_______
1d] Have you removed, cleaned, and tightened all battery connections? ____yes____
1e] Does your Wait to Start light come on for a time? How long? __normal_______
1f] Do you see smoke from the exhaust while cranking? What color? ___white when cold_____

2] Fuel Issues:
2a] Can you hear your life pump working? __yes__________
2b] Do you get a steady flow of fuel from the water drain (T-handle)? ____yes_____
2c] Loosen the inlet line from the IP – is fuel coming out? _____yes______
2d] Loosen an injector line and crank the engine - does fuel come out? ____yes_____
2e] Do you hear a vacuum (hiss) when you remove the fuel cap? ___no________

3] PMD / IP Issues
3a] Location of PMD (on pump, on intake, remote mounted) ___intake________
3b] Condition of Extension harness (if used) Vendor or Homemade? __none_______
3c] Condition of grounds / ground wires to IP / PMD. Check Harness. _____good____
3d] PMD Make: ____stanadyne_______
3e] PMD Age: __2007___________

4] Stalling Issues
4a] Do you experience stalling only when hot? ____no________
4b] Does it stall under particular circumstances? (ie hit bump, or on accel) _no_____
4c] Does pouring cool water over the IP seem to help with restarting? ___n/a______
4d] Is stalling momentary (engine recovers)? _yes________
4e] Does SES light come on when engine hiccups? ___no______
4f] Does cruise control quit working when engine hiccups? _N/a________
4g] Does re-starting seem to reset engine, restoring cruise and power? _____n/a_
4h] Changes to dash lights or instruments during stalling events? _____n/a___

5] Running Issues
5a] On cold start, does upper rad hose get hard before engine warms up? ____no_
5b] Any bubbles or oil film in coolant overflow tank? _no____
5c] Any white slime on oil surfaces (dipstick, CDR, oil Fill cap)? _no_______
5d] Excessive white smoke from exhaust on cold start? ___not really
5e] Excessive black smoke from exhaust under hard acceleration? _____not really
6] Performance Issues
6a] Do you have gauges? ____boost, eng temp
6b] Maximum boost under load? ____________
6c] Have you added a performance PCM (reflash) or Chip? _not yet______
6d] Have you changed exhaust / downpipe / crossover? __yes 3" open___
6e] Wastegate – mechanical or vacuum? __mech________

7] Temperature-related Issues:
7a] Single or dual thermostats? _single_____
7b] Have you replaced them lately? Manufacturer of replacements? ____2007_
7c] Have you pulled and cleaned Radiator and coolers lately? __2007______
7d] Have you replaced the fan clutch? Manufacturer of replacement? ___no___
7e] (winter) Have you tested your antifreeze? Good to what temp? ____-30___
7f] (winter) Are you using a winter grille cover? ___no______

List and describe any other factors which are not addressed in this checklist. We can’t see, hear, smell, or touch your truck, so the more descriptive information you can give, the more likely it is that somebody can assist you.

_changed from auto to manual___

 

[Turbine Doc]

I added some color hard to read the diagnostics thus far, you say lift is good, how did you check it, is pressure being sustained at power, lift can run and make pressure at idle but fail at load causing hesitation/surge, gnd and OPS on OBD-I trucks is prime culprit, when lift is new, another suspect is fuel quality, did you get a bad load with water or snot which has partially plugged a fuel filter, even recent changed one, sock in tank can be snotty as well.

You should do a hiway load check, with gauge hooked to filter mgr drain line, run into cab and see if supply fm lift is being maintained at power.

Your driver on intake is also suspect, not a matter of if on intake, but when it will fail again.

 

[Bullseye240]

Listen to TD, he knows his stuff here. Mine had similar symptoms and he turned me onto the Walbro FRB-5 pump and I love it. Approximately same price as stock and rebuildable and maintains good pressure and flow at speed. Also a good idea to install a spin-on filter in between the pump and tank.

 

[625fireman]

Thanks TD for the color I tried it when I posted but it aperantly didn't work. i had a gauge teed in all summer and psi never went below 6 will driving. My biggest concern was leaving the jumper in when I started it that one time. GM manual says ECM failure WILL result from that. But with the sparatic nature of this I don't think it is the ECM. As for the sock it is gone took it off a while ago when i had trouble with water getting into my tank. (I actually melted it last winter trying to thaw it out) The pick up line bends on the sending unit had holes in them, swiss cheese sydrome. The other thing is with the water I had maybe that wiped out the IP??? I am also thinking of exstension harness for PMD just haven't done it yet. TD or Bullseye, Where can I find the Walbro pump? I have not heard of that one yet, I know GM has one, as well as Carter (which is what I have).

 

[Turbine Doc]

got mine from Eric at Hoesli Diesel http://www.hoeslidiesel.com/ but try the site vendors 1st to see if they can get it for you Walbro FRB-5 is the pump # and Walbro sold by many distrubutors, I'll be posting some data soon I just took while towing with the Walbro in operation, FRB-5 is far superior than any other pump I've tried thus far.

Your fuel filter should have prevented damage to IP they are treated with water block chemical,

Am I to understand you are running sans sock in tank, what is protecting your lift pump?, also that would lend itself to early plugging of the on engine fuel filter which blocks everthing 5 micron & bigger, with rotten steel lines, I'll surmise you have some corrosion in tank also.

Have you for sake of troubleshooting tried a new fuel filter, try it even if it means storing it on shelf for later and you put the one in it now back in.

 

[625fireman]

Correct no sock but have in line filter before the lift pump. Before you ask I cannot see any bubbles coming in from there. As for corrision in tank when new pickup went in I did not see anything upon inspection (after cleansing of coarse). I also replaced the fuel lines from the tank to the filter then too. Don't tell the feds but I have noticed the engine likes "red" fuel better than clear fuel. That I don't think is no suprise they probably all do

 

[SnowDrift]

Can you give us more details on "sputters while driving" and on "lopes at idle"?

A cracked metering valve was causing these symptoms on mine this past summer.

 

[Bullseye240]

Any place it can get air in the lines will cause it to sputter/stall as air is easier to pump than fuel. Don't tell my wife, but when I installed the FRB-5 I found one of my lines on the front side of the old LP was lose enough to take of without a wrench and most likely causing most of my problems. That being said I wuld still reccomend the FRB-5 as it is rebuildable later saving some money in the long run.

 

[625fireman]

snowdrift it actually seems like it misses then it will run fine. It runs fine before even no preemptive signs. The loping thing is like this it will vary the RPM's from about 750 to 1200. No matter if it is warm or cold. But if I load the engine it will quit for a while. (Putting it in gear, hold on th brakes, let clutch out just enough to lug engine, push clutch in, take out of gear, and it will idle at 900 rpm).After about 5 min it will start loping again. makes warming the truck up in the cold difficult. PS I do plug the truck in when cold but it doesent matter does year round.

The metering valve is where??? The only thing I can think of is the pressure valve on top of the IP, is this what you speak of?

Bullseye I have not tried to tighten my lines yet but another good place to look. Will try tonite.

 

[625fireman]

I think i figured out the "miss" problem. Wed. finally had enough of it and tore into it. Found that the stupid battery cables (+ side of the stacked leads) were not completely tight. Found the bolt fix idea on this site and did that seems to have fixed it for now. But it still lopes while idleing that will dug into next. One interesting thing I found though was that while checking for shorts you cant do the old trick of disconnecting the grounds off the battery and checking for voltage on the block doesn't work on 6.5's. It must be something with the glow plug circuit. (tried on both my 6.5's they both acted the same) I had battery voltage on the block and body, but it had an res. reading of 1.78 when a checked continuty. Dad's 02 gasser still worked with the old trick but the 6.5's didnt.

 

[RadioMan]

the old trick of disconnecting the grounds off the battery and checking for voltage on the block

??????????
I'm old and know most of the *tricks of the trade* but, I confess, I have no idea what you're typing about. I'm always up for a new trick!
Would you please explain?
Thanks!

 

[625fireman]

Take the grounds off the battery(ies). Then use either a test light or voltmeter. Connect ground of light or meter to the battery, then take positive from meter or light on the block or chassis to look for shorts. If you have voltage or light illuminates start pulling fuses till light goes out or voltage drops. This will head you to the right circuit hopefully, if you have a short. There are two things to watch out for. (1) make sure you also unhook the bonding ground between the block and chassis and body this will show wether the short is on the block or the chassis. (2) when checking the courtesy fuse make sure the door buttons are pushed in.

 

[RadioMan]

Thanks - I got it now.

Try looking for current (Amp scale) instead of Voltage using your method. The higher the current the lower the resistance of the *short*. If the glow plug controller is causing you to always see current pull the Red wire feeding it. It comes directly from the batteries (maybe through a distribution center somewhere) and is protected by a fusable link in the wire, not a fuse that you can just pull.

 

[625fireman]

I was looking at unhooking the glowplugs to check that too but ran out of time. I honestly dont think I have a short. I was looking for some reason the thing would miss once in a while, but I think I found it with the positive cable connection. it hasn't done it since I changed out the bolt. Next is it figure out the loping at idle deal. I am thinking either the throttle pedal or the ECM. Having another "good" truck is nice to steal parts from to check problem is nice.

 

[NoInterstates!]

I spent a year tracking down a idle/power rough condition, maybe the timing chain, or the woodruff key/ crank timing gear being damaged. Not sure if the damage I found on my rig was a normal 6.5 condition, or the product of an aftermarket clutch and flywheel.