ECM or something else?

[Ihasfip]

Hi guys. New here. Been around these things for a long time, but don't know Cummins like you guys do. I come from the rockcrawling world, and know a lot about LS stuff, and worked on lots of different diesels over the years, but not lots of cummins stuff beyond 12v.  I need some help. Have a few issues on this cobbled together hooptie. 

 

Bought this truck as a tow rig, as my Bil's buggy will fit on the rear and it can tow my crawler behind it. Supposedly it was running and driving and then wouldn't start one morning. Tried and tried to get it but couldn't. Had some "diesel mechanic" diagnose it as a bad VP44 due to codes etc. Removed it and then he couldnt afford to fix it so listed it.

I bought it. Put a new Thoroughbred VP44 on it. New RV275s. New injector tube seals. Resealed oil pan, timing cover, tappet cover. Sumped the fuel tank. Deleted the metal return line and T from the VP44, and replaced with AN lines and Banjos to AN. Bought big nice battery cable kit with all the engine/chassis grounds etc. 2 new 31-5 18wheeler/tractor batteries. And a new starter. Cracked open injectors 1 - 3- 5 and got it to start up. Closed injector lines. Ran great. But couldnt get them to quit seeping after you drove it. And it would get progressively harder to start after it sat. Bought a new set of aftermarket lines (not the cheap ones, but ones with good reviews) and they sucked and didnt fit at all. Ended up pulling a set off another running engine I have here and put them on. I have got all but 1 injector line to quit leaking. It will weep a little after you run it and turn it off. Enough to get damp on the head around the line. Ive held my mouth every which way, assembled him in every different order, and this time with this one just barely weeping is best I have been able to get. I get 17 psi key on engine off. And 14i-15sh at idle running. Air dog runs constant with key on but is interrupted during starting as I read was the correct way to do it. 

 

Another piece to the puzzle is the tach only works for first 5 seconds when you start it and then it goes away. But I can plug in my ancient snap on scanner and see RPM, codes etc. I found out when doing that, that the vin in the ECM shows to be a 2001 model with a manual. I have another 98.5 truck and I swapped the ECM to this truck and the vin in it is a different 2001 with an auto. Truck runs same with both of them. Just one has codes for trans. I changed crank sensor behind the starter (with an oreilly one, not a cummins...I know I know...but don't even think its bad). Also sometimes the WTS light is delayed or doesn't come on, which I believe points to a dying ecm. So reflashing to the correct tune for this truck likely wouldn't even fix it completely. So is a repaired ecm with correct flash the fix?

 

Heres where it gets more interesting. You can park it overnight. Try and start it and crank and crank and nada. Doesnt matter if flat ground/up hill or down. But you can roll it like 10 ft and pop the clutch and itll fire right up and run smoothly. Not like it has a bunch of air in the lines. It also will start up with the starter fine after that. But the longer it sits after you turn it off the harder it is to start. I cannot find any leaks what so ever except the one weeping first injector line. I have put air to return side and get no wet spots or anything at any of the connections and itll hold 20 psi no problem.  Is this one weeping injector line enough to make it not start after a few hours of sitting? I have an old tractor that leaks from about everywhere and it starts almost as fast as a cummins normally does... 

 

So couple different issues, just not sure what is causing what. So thats where I am at. I have a buddy and his uncle that have like 40 old cummins trucks and such around his place. His uncle been obsessed with em since the 80s and has parts coming out his ears. And they are stumped too. 

 

He is getting his breakout box today and checking the vp44, it is brand new, but...it is a vp44.

 

Sorry for such a huge first post. Thanks for any help you can give. 

[Tractorman]

1 hour ago, Ihasfip said:

Heres where it gets more interesting. You can park it overnight. Try and start it and crank and crank and nada. Doesnt matter if flat ground/up hill or down. But you can roll it like 10 ft and pop the clutch and itll fire right up and run smoothly.

 

Have you push-started the truck with the same results BEFORE you tried starting the engine with the starting motor?  If not, the engine may have coincidentally been ready to start during the push-start.

 

After a night of setting, try doing a push-start without use of the starter beforehand.  If the engine starts right away, this could indicate that there is an excessive voltage drop to the ECM or to the VP44 solenoid valve when the starter motor is cranking the engine, consequently, no fuel.  If the engine still doesn't start right away, then this is not likely a cause. 

 

As far as the one injector line that is leaking, it is not unusual a line to leak at that connection point with new crossover tubes.  Each injector line seals as a metal to metal sealing connection at the crossover tube.  The new crossover tubes may have a slightly different surface sealing area shape than the old crossover tubes.  Try loosening nearby clamps and then loosen the offending injector fitting.  As you are re-tightening the nut, try rotating the line back and forth slightly while maintaining some friction using the nut.  The objective is to grind the two mating surfaces together to smooth out any surface irregularities.  Don't be aggressive. 

 

- John

Edited 4 hours ago by Tractorman

[Ihasfip]

57 minutes ago, Tractorman said:

 

Have you push started the truck with the same results BEFORE you tried starting the engine with the starting motor?  If not, the engine may have coincidentally been ready to start during the push-start.

 

After a night of setting, try doing a push-start without use of the starter beforehand.  If the engine starts right away, this could indicate that there is an excessive voltage drop to the VP44 solenoid valve when the starter motor is cranking the engine, consequently, no fuel.  If the engine still doesn't start right away, then this is not likely a cause. 

 

As far as the one injector line that is leaking, it is not unusual a line to leak at that connection point with new crossover tubes.  Each injector line seals as a metal to metal sealing connection at the crossover tube.  The new crossover tubes may have a slightly different surface sealing area shape than the old crossover tubes.  Try loosening nearby clamps and then loosen the offending injector fitting.  As you are re-tightening the nut, try rotating the line back and forth slightly while maintaining some friction using the nut.  The objective is to grind the two mating surfaces together to smooth out any surface irregularities.  Don't be aggressive. 

 

- John

Honestly been messing with it for couple weeks now, I am pretty certain I have roll started without trying to crank it first, just with the key on and the airdog running. I know I have tried starting with airdog on, air dog on for 25 secs and then off like factory or whatever. Makes no difference. I will find out tomorrow. Assuming snowpocalypse 2025 doesnt prevent me from messing with it tomorrow. 

 

As for the lines, I didnt change the injector tubes, and still couldnt get the original set to quit leaking. This set off the other truck I have, I got them down to just the one barely weeping after driving for a long time.

 

One injector line barely leaking like that isnt enough to make it not start that quickly is it?

 

 

D

 

Edited 3 hours ago by Ihasfip