N14 Tech problem

[Truck Shop]

Need some ideas on a friends N14. Will run with a shot of ether, trouble starting hot or cold. Engine has new piston
liner packs and three new heads. Ran engine out of a bucket of fuel to omit the hoses and tanks- same problem.
This truck has been to four dealers including Cummins no success. List of parts changed related to fuel system.
Injectors, pump, solenoid, crank sensor, ecm. I'm leaning towards low voltage issues or grounds. Truck is a 96 IH.

Thanks for any ideas

Truck Shop

 

[Junkyard]

Good compression? Seems I recall some N14's had harness issues like a connector or the pins in the connector making poor contact or pushing out of the connector. I had one that missed bad, another "mechanic" replaced the same injector twice before I found a bad connection. Overhead set right? Who did the inframe? No cam or valvetrain issues? ECM or issues in the main harness? Had a Cat once that had a broken wire near the steering shaft that would make contact when you turned the wheel just right. Maybe ground like you said, looks good on the outside but is trash inside....

If all the hard parts are good it could very well be electrical. Good fuel pressure I assume? Is there a fuel leak in head, supply not making it to injectors like it should? Computer trying to shut it down because it sees something it doesn't like? Engine protect mode you could say?

Lots of maybes there. I'm curious to see what it turns out to be, we will all learn something. Good luck

Junkyard

 

[Planedriver]

^^^^^ +1 junkyard^^^^^^
I ran into a similar problem with my N14 (1996). My trouble was corrosion on the celect module terminals.

 

[grandpa]

There is an electronic throttle module above the foot pedal. If that is malfunctioning, it won't turn the fuel to the injectors on.

 

[repowerguy]

Does it run fine with good power after the initial hard start? Maybe the check in the fuel line on the ecm cooler is stuck open. A quick back probe of the ecm plug will tell the tale of voltage drop problems.

 

[Ruger_556]

Define "trouble starting"... Cranks until it has fuel pressure and then starts immediately or what? I second the check valve letting fuel drain back if that is what it is doing.

 

[crane operator]

My m11 IH 1995 had a injector bad code (different motor, but still celect)- misfire on #5. Cummins said ecm, all injectors, and harness needed replaced (lets just throw parts at it shall we- that's $6,000, for about a $8,000 truck) I swapped injectors around, problem stayed at the same injector, so.....

I sent the ecm off (ebay repairman @$500), problem persisted- ended up being in one of the two harnesses between ecm and head/injectors (I replaced both). Wires all looked good on the outside, it was either bad inside the insulation, or I think it was at one of the end connectors. Either way, the new harness did the trick.

I don't think all the heat and oil inside the valve cover does that wiring loom any good, seems they may have about a 20 year life?

 

[RZucker]

This is a tough one. I would jumper the oil pressure sensor to rule that out, maybe throw a mechanical gauge on it to check the oil pressure rise when cranking. Some were set up to not fire til they had oil pressure. I would also pressure check the ECM cooler, ran into that a while back on a Case loader with the 6.7 engine. The leak didn't show 'til I pressured the system from the tank end. and another thing to try is putting 12V to the solenoid valve before cranking just to see if that makes a difference. Although it wont help if the injectors don't fire. And last but not least... check to see if the inner seal is on the secondary fuel filter nipple. I dropped one once and that truck took a bit of crank time 'til I realized what happened.

 

[Truck Shop]

Well to answer the questions above

The overhaul was done by owner {a very experienced individual on diesel repair}.
The ECM oil cooler was changed along with the ECM
Engine has good compression, injectors adjusted OBC method with dial indicator.
Even when engine does run and is warmed up and shut off if you immediately try a restart it won't fire without a whiff of ether. If you turn the key off while idling and before the engine comes to a complete stop, turn key on it will fire back up.
Fuel pump pressure has been tested it's fine.

He is in the process of inspecting all the harnesses,cleaning connections. It's 2:30 pm I'm going to go and check on him and see how he is doing. I would be working on it also but my last seven days have been 10 to 11 hrs. This afternoon
is my first half day off.
Will keep any progress posted

Truck Shop

 

[Knepptune]

Sounds like when cranking the voltage is dropping to low to fire the injectors. I've seen this on several manlifts and lulls. And on those, the engine absolutely spun fast enough. It just had enough corrosion or bad enough connection for the voltage to drop to low while cranking. Absolutely wouldn't start without a whiff of ether. I'd check voltage to the ecm while cranking.

Had a manlift that did that and found out the ign wire was hooked to the acc post on the key switch. It had to run on ether just long enough to let off of the start on the key switch. Switched the wire to the proper post and it started like a scared rabbit.

 

[RZucker]

The above sounds like an oil pressure sensor issue to me, just sayin'. I had a customer with a 60K Cat reman 3408 in a D-9N that was ringing the alarm after 2 days run time, the mechanical gauge showed good oil pressure, but the sensor had a small bit of rebuild debris plugging the port.

 

[ohiofleet]

i had a c15 do the same thing replaced starter and it fixed it it just wasnt turning fast enough to start but sounded like it was also what it you jump power to fuel sylinoid

 

[Tenwheeler]

I thank all of them have a low voltage disconnect. If the voltage is to low, 10.2-9.6?, it will not fire injectors as mentioned. Poor grounds, power supplies, a starter drawing to much current could all cause this. A poor oil sending unit should let it start, run and then shut off. Do you have any flashing lights on dash? What color are they and count the flashes. Google IHC & or N14 flash codes.

 

[Truck Shop]

I got her running, now for the trouble shooting story.

I checked the proper pins in the actuator connector to the ECM for power, that area was ok 12v to every pin that should have 12v.
Then with injector harness unplugged I fed 12v's through each injector circuit, injector harness was ok. Plugged everything back
and left one injector unplugged and plugged in a Noid light then fired the engine off with a whiff of ether. I noticed the light was very
dim on cranking and only a little brighter after it was idling.

After thinking about it for a bit I called and ordered a new timing sensor and oil pressure sending unit while the owner was standing there.
He immediately started to argue that the timing sensor was only two months old. The oil sender was original and oil port didn't look right
the opening for oil was 3/16 in diameter-never seen one like that.

Installed the oil sender still wouldn't start, installed the timing sensor it fired up on three revolutions cold. This engine for the 21 years he
has owned it has always cranked at least 7-9 revolutions before firing hot or cold. The faster starting I will give credit to the oil sender.
The Noid light was real bright also.

This engine over the years has had 4 timing sensors replaced. The one I removed was one he bought through NAPA. I know the parts guys
there real well so I gave them a call to see if they would help him out on warranty. The mgr told me those sensors are defective been
having complaints everywhere.-------------I only use Cummins, Cat & Detroit parts.

Because it was a new sensor my friend Steve just knew that wasn't the problem. Self inflicted running in a circle.

Truck Shop

 

[RZucker]

Funny that you mentioned OEM parts (which I believe in). two years ago I replaced 3 cam position sensors on a Case/IH combine with the Iveco engine. It would run 20 hours and start up the same game as before. I had checked the tone wheel on the cam gear, it wasn't loose, Case warranteed the engine harness (their call) Finally the fourth sensor cleared up the problem. To this day they say "We have never seen that before". Weird thing is the sensors all ohmed out just fine and seemed to act the same when you passed steel across the nose. Go figure.

 

[Ruger_556]

I got her running, now for the trouble shooting story.

I checked the proper pins in the actuator connector to the ECM for power, that area was ok 12v to every pin that should have 12v.
Then with injector harness unplugged I fed 12v's through each injector circuit, injector harness was ok. Plugged everything back
and left one injector unplugged and plugged in a Noid light then fired the engine off with a whiff of ether. I noticed the light was very
dim on cranking and only a little brighter after it was idling.

After thinking about it for a bit I called and ordered a new timing sensor and oil pressure sending unit while the owner was standing there.
He immediately started to argue that the timing sensor was only two months old. The oil sender was original and oil port didn't look right
the opening for oil was 3/16 in diameter-never seen one like that.

Installed the oil sender still wouldn't start, installed the timing sensor it fired up on three revolutions cold. This engine for the 21 years he
has owned it has always cranked at least 7-9 revolutions before firing hot or cold. The faster starting I will give credit to the oil sender.
The Noid light was real bright also.

This engine over the years has had 4 timing sensors replaced. The one I removed was one he bought through NAPA. I know the parts guys
there real well so I gave them a call to see if they would help him out on warranty. The mgr told me those sensors are defective been
having complaints everywhere.-------------I only use Cummins, Cat & Detroit parts.

Because it was a new sensor my friend Steve just knew that wasn't the problem. Self inflicted running in a circle.

Truck Shop

Napa sensor defective? That would never happen... Lol. Don't credit the oil pressure sender for faster starting, it isn't capable of inhibiting start, it can only shut the engine down after starting and there is a time delay.

 

[Truck Shop]

Napa sensor defective? That would never happen... Lol. Don't credit the oil pressure sender for faster starting, it isn't capable of inhibiting start, it can only shut the engine down after starting and there is a time delay.

Not according to my Cummins manual. The real strange part of this problem is the timing sensor hadn't completely failed. It would still start and run with the aid of ether. The fact that the Noid test
light was brighter after changing the sensor is very odd also, it should not have an effect on the injector voltage,IMO.

 

[RZucker]

N Don't credit the oil pressure sender for faster starting, it isn't capable of inhibiting start, it can only shut the engine down after starting and there is a time delay.

Never say never about the oil pressure sensor. I've seen more than a few that had to see oil pressure to fire. Not all ECMs have the same programming. Most of the ones I have seen were off road equipment but I have worked on a fleet of Peterbilts with 3176 and C12 cats that had that program. We had to add an override switch to get them fired in cold weather.

 

[Ruger_556]

Not according to my Cummins manual. The real strange part of this problem is the timing sensor hadn't completely failed. It would still start and run with the aid of ether. The fact that the Noid test light was brighter after changing the sensor is very odd also, it should not have an effect on the injector voltage,IMO.

You can unplug the sender, put a jumper wire in it to fool the ECM into thinking that oil pressure is '0' and it'll start anyway, that engine doesn't need it to start.

Never say never about the oil pressure sensor. I've seen more than a few that had to see oil pressure to fire. Not all ECMs have the same programming. Most of the ones I have seen were off road equipment but I have worked on a fleet of Peterbilts with 3176 and C12 cats that had that program. We had to add an override switch to get them fired in cold weather.

Well, true... I shouldn't say never but on an N14 it won't do that.

 

[Truck Shop]

This truck is an IH the sender is unique to that IH dash. Now I didn't start this thread for it to turn into a back and forth on weather the truck starts faster with a new sender or not.
The fact is it does start faster and I doubt very much that every previous timing sensor caused excessive cranking to start. This thread has ended.

Truck Shop