No Start, mechanics have no clue

[bachataBus]

Skoolie folk, I'm out of ideas. I've got a 1997 International 3400 with a t444e. When we picked her up, she wouldn't start the next morning, it turned out we had a leaking banjo fitting at the mechanical fuel pump. It would leak very slowly, lose fuel prime, and not be able to start the next morning. A squirt of ether would get her moving (I realise that's very dangerous, but when you gotta move you gotta move).

I ordered new sealing washers, replaced them on the banjo fitting, seems to have stopped the leak. However, we still have the same problem. So I took it to a great local shop, told them about the fuel system, they tested everything under the sun. No idea what's wrong. Recommended I look into changing the ECM, but that just seems to be the... "I dunno, that's the computer that controls everything, give that a shot" solution.

Current symptoms:
Won't start if she's sitting for a looong time. Like, 24+ hours. It'll jump to life after 12+ hours in the cold, so it has nothing to do with engine temperature.

Things I've tried:
New glow plugs and harness
Replaced the banjo fittings (fixing fuel leak)
New air filters
Checked compression (380+ on all cylinder heads)
Checked all injectors are firing
Added stiction eliminator, Archoil, and Lucas fuel treatment
Gave a mechanic 2+ grand

Any ideas?

 

[Booyah45828]

What's your fuel pressure while cranking? What's your injection pressure while cranking? Is the cam sensor showing rpm while cranking?

These are all things I would look at before throwing a pcm at it.

If you have a loss of fuel pump prime, it will show up as low fuel rail pressure while cranking. Once the pump reprimes and purges the air, you'll then have fuel rail pressure.

 

[CHEESE_WAGON]

Could be one or more injectors leaking down too. Could also be extremely dirty or gummed up injectors, which would also allow them to leak down if they are sticking open. With a diesel, it's just fuel and air, regardless of whether a computer is in the mix. I didn't see mention of fuel filters, though I may have missed it because I've been on pain meds from oral surgery. Are they possibly impeding fuel flow?

 

[cadillackid]

all good things to cvheck have been mentioned..



1. connect a mechanical fuel pressure gauge to the schraeder valve up by the fuel bowl.. this is a mechanical pump but while cranking you should see the needle pulse up and down right away as soon as you crank.. if you dont then your system is still losing prime.


2. im assuming the mechanics had a computer scanner they were running on the ECM so they could verify that the Cam sensor is reigstering RPM while cranking. and that the HPOP pressure is coming up while cranking?

 

[bachataBus]

I will try to check some of these. I don't have a computer that can check if the cam sensor is reporting the rpm, but maybe I should get one. I can also call the garage tomorrow to see if they ran these tests. I'll update tomorrow.

 

[bachataBus]

Sorry for the delay, I have a few new stats:
Fuel pressure is 42 psi while cranking, in spec
Oil pressure is 3000-3200 psi in HPOP, in spec

But, the barometric pressure is reading 15.9, and it should be 30. Unplugging the barometric pressure sensor, the pressure remains at 15.9, but it should default to 29. This to me seems like much stronger evidence for something wrong with the ECM. Additionally, I have a few codes:

DTC 152, Spn 108, Fmi 4 - Barometric Pressure signal out of range low
DTC 224, Spn 254, Fmi 2 - Flash Memory Fault

I also have an inactive code, DC 615 SPN 254 FMI 13 - Programmable Parameter Keep Alive Memory Corrupt. Seems like I might have a failing ECM. Any experience with a failed ECM? Is it something I can replace myself? Any advice on where to get one?

 

[Booyah45828]

Those codes will cause a no-start for sure.

Any time I see a kam memory code, like 224, I check to make sure the batteries are good, connections are good, and the pcm is getting battery voltage. The pcm has a seperate wire that has it's own fuse and connects directly to the battery that I've seen people forget to connect more times then I'd care to count. If you're certain, and I mean absolutely certain, that it's all good, then you can move onto replacing the ecm.

As far as your baro sensor code is concerned, I wouldn't necessarily jump to condemn an ecm because you unplugged a sensor and the reading didn't change.

That sensor is supplied 5v from the ecm, a return path to the ecm, and a signal wire that varies it's voltage based off of barometric pressure. So I would first verify that you have 5v to the sensor. If you do, I'd then check that the signal and return wire has continuity back to the ecm and neither are shorted to positive, or ground.

If you don't have 5v to the sensor, then you need to check to see if you have it at the ecm. If you don't have it at the ecm, I'd suspect an internal ecm fault and replace.

If you find all the wiring good, then backprobe the signal wire at the ecm and see if the displayed voltage matches what you have backprobed. If it doesn't match, then you can suspect the ecm, but I've rarely seen them fail that way. Normally, if it is an ecm failure, they'll fail to produce a 5v supply, leading your signal voltage to be off.

 

[CHEESE_WAGON]

Okay, Booyah has some great points, but I'm gonna ask a few potentially dumb questions here. And please don't take this as condescending or treating you like an idiot. I only ask because most people don't truly understand diesels.

Is the glow plug controller working? Are all the glow plugs working? And are you allowing adequate preheat time before cranking? Is there a heater grid in the intake, and if so, is it working properly and being allowed adequate preheat time?

Some diesels need a little heat in their first few breaths to ensure a start. Also, if an engine has been hit with ether enough before your ownership, it could be dependent on ether. Many diesels will get to where they won't fire without it if used too often. And unfortunately, not much, if anything can be done about it.

 

[Native-SKO]

I did not know a machine could become an addict!

 

[CHEESE_WAGON]

I did not know a machine could become an addict!

That just made me think of a "CARS"-style, psychedelic stoner hippie bus in tie-dye colors, saying "Far out, man!", Tommy Chong-style.

Seriously, though, it can and will happen. I think the lack of lubricity causes gradual damage to the rings and cylinder walls, thereby causing fluctuant / uneven compression or even gradual compression drop over time, which would make it harder to fire and more reliant on ether.

Some diesels are factory-equiped with ether injection. Not common, but it's good to know this about your bus if so equipped.

 

[Native-SKO]

Pass the ether, man!

 

[CHEESE_WAGON]

Pass the ether, man!

Don't try this at home, kids...

*cues up Cypress Hill - I Wanna Get High*

Brings new meaning to "Magic Bus", doesn't it?

 

[orangebus]

BAD ground.

 

[CHEESE_WAGON]

BAD ground.

Could be... Bad ground could take down your entire engine control system.

 

[cadillackid]

a bad ground is certainly possible.. there are multiple grounds that go to these computers.. sounds counter-productive however ive seen small amounts of voltages between grounds cause issues.. I expoect to see a lot of voltage and 600 series codes though when that happens as it messes with the internal communications of the modules..

 

[CHEESE_WAGON]

Here's another thought. Cranking speed is essential on a diesel. Are you sure the starter and batteries are giving sufficient turnover to fire without assistance?

 

[bachataBus]

I pulled the ECM out today, cracked it open, and it is frustratingly *spotless*. No bad connections, no bad components (singed connections, bubbling plastic, oxidized solder), everything is visually 100%. The error codes are specifically for corrupted RAM, so I'm guessing I have to replace the ECM. I also followed the diagnostic service manual procedure and determined that the circuit around the barometric pressure sensor is all good, and since I'm reading a bad pressure, the sensor is likely bad.

Although the mechanic said he could unplug the baro sensor and nothing would change, I can't replicate that. I meaure a wrong pressure at the computer, but when I unplug the sensor the pressure reading goes away completely. I wonder if the mechanic is able to see something I cannot with my computer. Regardless, since I'm replacing the $400 ECM, figured I'd replace the $40 baro sensor too.

 

[bachataBus]

Also, can I say,

I understand ether is bad.

I cannot explain how frustrating is to read in every thread where someone is clearly trying to fix their engine, and has resorted to ether, the legion of commentors who chime in "ether just covers the symptoms, you better find the root cause and fix it". I honestly cannot imagine anyone who has used ether has thought it was good. It puts a pit in my stomach every time I spray a ***** explosive into my engine, but I literally do not have a choice. The bus is not on my land, I am not lucky enough to own that space, and I have to move it. I have spent thousands of dollars at mechanics trying to fix it. Please try to be more empathetic to the people who are in dire engine troubles!

 

[CHEESE_WAGON]

I also followed the diagnostic service manual procedure and determined that the circuit around the barometric pressure sensor is all good, and since I'm reading a bad pressure, the sensor is likely bad.

Although the mechanic said he could unplug the baro sensor and nothing would change, I can't replicate that. I measure a wrong pressure at the computer, but when I unplug the sensor the pressure reading goes away completely.

Something to consider. The sensor may ground through the ECM and once the circuit is broken the reading ghosts out. Something that is common but overlooked in regard to barometric pressure sensors is conventional gas engines have these connected to the engine through a hose to help it draw vacuum, as they help the ECM determine the Manifold Absolute Pressure (a mean value of pressure inside intake manifold and outside ambient air pressure). Not doable on a diesel as they don't generate vacuum, so I am guessing this sensor simply reports ambient. Either way, it certainly sounds like the ECM and the sensor need each other in order to complete the circuit and get any reading at all.

 

[musigenesis]

As someone also about to drop thousands at the shop (to add on to the total), I empathize.