I need HELP!

syrupdawg

syrupdawg

GA Diesel Mafia
Joined
Mar 16, 2008
Messages
1,792
I've got a customers truck that is whooping my butt. Its a 2004 Cummins with 206k miles.

It was brought in running terrible with a miss. Hooked it up to scanner and determined it was injectors. Got brand new injectors from a reliable company. Put the injectors in got it all back together. It still has a miss and is running the exact same except now im not getting the injector code and the fuel pressure is way better at idle. Started trying to diagnose it, I could unplug injector harness A (Cyl 1-2) and theres a big change in idle (not them). Same with harness C. When you unplug B it hardly changed. Well I Ohm'd the injectors out and they all check out. I swapped another injector harness into it and no change.

Well the truck sat for a weekend and I came back on Monday and the batterys were dead. Not all the way dead but nearly. I charged it back up and swapped out the rail pressure sensor since I had a known good on at the shop. No change. So I swapped the FCA from a good cp3, no change.

Then the Thursday before fathers day my dad and I go out of town to go fishing. Come back Monday the batteries are as dead as they can be. I charge them up but now the truck wont even crank. It wont show any oil pressure and I keep getting a p0622 code which is generator field not switching properly. The alternator had quit before and he had an external regulator put on it. (I think his computer went bad and he did that to fix it). It is only showing 175 RPM when cranking on my scanner and on the dash. Well with that info I swapped a computer I had at the shop onto the truck and still no change :bang

On edit I even put 2 new batteries off my personal truck on it just to see if they could be causing it.

What could have changed that it wont run since the batteries completely died? Why all of a sudden is it not showing oil pressure? I checked to make sure it was still plugged in and it is. And what else could be causing it to run so bad? I haven't ruled out a bad injector yet but I need to get it running again to try and figure it out.

It really is whooping my ass and I need it gone and out of my way. Thank you in advance for any help.
 
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Check compression on the back two cylinders. Make sure your battery connections and cables are all good.
 
I would check compression/ scope the bore. It sounds like a bad cylinder. Maybe cut the filter


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I have seen a lot of harness issues with these things lately, the wires for the injectors will brake in the harness. As for the other stuff could still be harness related but could not be too. My advise would be to get your razor knife and start tracing out the wires.
 
Should have looked in the cylinders when you had the injectors out! Melted piston, burnt valve my guess. As far as batteries draining his regulator fix probably finally failed the ECM tells the Alt what to do. If there is a fault in the ECM may have finally failed completely. You put fresh batteries in it and an ecm and it still wouldn't crank fully? I would check the power wire to the Starter and the starter. Power drain wil need to be figured out any add ons in the cab? Start pulling fuses with a multimeter hooked up! Sorry for the obvious stuff just trying to touch all possible bases! As far as oil pressure put a mechanical gauge at the oil filter housing just to be safe if pressure is gone time for a tear down!
 
Pull the injector harness spacer and ohm harness b that you noticed the change with.. I just had a similar issue on my personal truck acted and diagnosed like injectors ended up being injectors and a dropped valve seat that took out #2 cylinder. But you definitely have something going to ground and draining the batteries sounds like I would start with the B section of that harness.
 
I'm thinking electrical. I have fixed several CR trucks that weren't running right with batteries, electrical, and shorted sensors.
 
I would also check the fuse block connections and the ignition switch very closely. Those trucks share common ground paths and I have seen some really weird crap from bad grounds.
 
I've checked all the grounds. The truck has zero blow by I checked that before and after the injectors. I can figure out what is causing it not to start. It baffles me that it would at least start and run until the batteries died.
 
Start at square one! Cranking amps good? Motor turning good? Fuel at the CP3?
Air should be a gimme but? Any codes? Power at the Injector harness? Zero blow by can be had with a melted piston!
 
very excellent suggestions here! i know ohming the injector harness can be testing.

i would have to agree with backing up a few steps before you go any further. I think you could be fighting two problems.

the motor turning over slow bothers me. be sure the "known good batteries" test out. then go after the starter.
I would get under the truck and do a full rotation with the barring tool and feel for any bad spots while cranking with the wrench.... it sounds like you know what your doing, you should know what to feel for.

as far dead batteries that quick, that screams grounding wire to me. can you unplug the charge wire from the alternator and check it with an ammeter?
 
Does the truck have anit theft stuff on it? I know batteries failing can cause that to go haywire.
 
Lostnwalmart said:
Does the truck have anit theft stuff on it? I know batteries failing can cause that to go haywire.
Click to expand...

This one doesn't have the anti theft stuff. Although the key will pull out of the ignition while it is running but I just figured it was wore out. I don't know how long it has been like that
 
Did you check the ignition switch connector? Those things are notorious for melting down.
 
I have had them do weird stuff. Delayed shutoff radio cut in and out, A/C cut out, low signal amperage for starting. If I have an electrical issue of any sort now on those trucks it is usually first thing I look at.
 
Runninlean said:
I have had them do weird stuff. Delayed shutoff radio cut in and out, A/C cut out, low signal amperage for starting. If I have an electrical issue of any sort now on those trucks it is usually first thing I look at.
Click to expand...

Ill check it out! Thank you
 
Okay messed with it a little this morning. I changed the oil pressure sending unit and still no pressure showing even though it has oil pressure (I checked with manual gauge). I can crank it and it wont show any pressure at all it just sits on the stop peg. When I let off the key and stop cranking it it will go up to like 20lbs and then comes back down.

Im pulling the key switch out after lunch just thought I would update with that information.
 
Yeah just disconnecting the plug from the switch should tell the story if it is an issue.
 
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