RIP CM2250, 2013, 800,000km 20,000 hrs

[Rawze]

(05-14-2022 )Hermjeji Wrote:  

(05-06-2022 )Rawze Wrote:  maybe monitor the commanded vs measured pressures and see if there are pressure spikes?.

See the test below, It looks like once it reaches peak command, it does spike up and down. The last spike was at key off. This is just at 700 idle with the leakdown test. It's obvious it fails the leakdown test. However, on the other 3 ISX's i have not seen this when doing the leakdown test, it fluctuates, but not this much. Even the old rail leakdown tests, they stayed at 28500-29000 psi, not jumping up to 30k and down like this.



I want to hook up to it when it's loaded and pulling to see how it data logs then (but that won't be till Tuesday/Wednesday).

So far, it does not look that unusual besides failing a leak test. It is normal for the pressure to fluctuate about 200~ish bar or so. The fuel system pressure regulation works like any other hydraulic bypass-charging system, so the up/down fluctuations are normal within that range. 300 bar (if memory serves me right), maybe is max before setting off alarms.

Just for FYI purposes:
- Unlike a low pressure hydraulic system with a spring regulator...,. a hydraulic bypass-charging pressure regulation works by closing a valve so that the pump can make/build up the pressure. Once the pressure is reached, then the valve opens again, putting the pump into 'neutral' .. not allowing it to supply anything until the pressure has fallen off again by a certain amount. .,. then the valve shuts again to top it off whenever it is needed only. - this makes the pressure go up and down constantly by a few % as the fluid gets consumed, does work, etc. and the valve opens and closes due to pressure drops.

It is the equivalent of a truck going down the road and the driver shifting it in and out of gear, back into neutral once it gets up to speed... and then going back into gear after it slows down a bit, so that the average speed can be kept up ... unlike one that may have the the cruise control set and remaining in gear all the time, keeping a very steady speed,,. always in gear, wearing things out.

[Hermjeji]

So.

Head #6, new actuator, new fuel pump actuator housing, new fuel pressure relief valve. After 12 hours of operating, started losing power again. It's failing the leakdown test now, but it can't make pressure above 20,000 psi. No visible leaking on the top of the head yet, but I assume another several hours of running and it would start.

I am getting an odd ticking sound coming from the main rail line (also when the key is turned on, it takes a while for the usual ticking noise of the pressure being built up to stop). I'm going to pull the valve cover off, and see if something else is going on (also due for an overhead). But, could anything on the top end be causing these repeated fuel pump heads to go? I don't know what to do at this point.

[Rawze]

(06-14-2022 )Hermjeji Wrote:  So.

Head #6, new actuator, new fuel pump actuator housing, new fuel pressure relief valve. After 12 hours of operating, started losing power again. It's failing the leakdown test now, but it can't make pressure above 20,000 psi. No visible leaking on the top of the head yet, but I assume another several hours of running and it would start.

I am getting an odd ticking sound coming from the main rail line (also when the key is turned on, it takes a while for the usual ticking noise of the pressure being built up to stop). I'm going to pull the valve cover off, and see if something else is going on (also due for an overhead). But, could anything on the top end be causing these repeated fuel pump heads to go? I don't know what to do at this point.

I would not think so, but one never knows in an odd, extreme case like that. Maybe a severely leaky injector with its internal check-valve failed, back-feeding cylinder pressures into the rail?, but that would also mean it fails a leak-down test.

It almost sounds to me like bad fuel.. or contaminants keep getting in .. perhaps something letting coolant in the fuel, air, something causing repeated pump failures.

Otherwise, fuel pumps do not just fail over and over completely on their own unless someone is using aftermarket (or the wrong ) parts in them.

Are the bottom of the fuel tanks clean and free of coolant, moisture, etc?. upon inspecting them with a bright light?

Does the commanded fuel pressure vs. the measured show a higher pressures than commanded?. and/or when test driving it at high engine loads?

Also, make sure the ecm does not have a crappy delete program in it. It could be over-working the pump .. that can happen too, but I doubt even that would cause failures so often.

[Hermjeji]

So this trucks been sitting for a few weeks now as I start to get ready when I have time. Is there a way for me to check injector performance when the pressure being measured is 10,000 psi less than commanded? Head is not leaking externally at this point. I don't think i can do the return flow test for the injectors if I'm not making enough pressure? Or can I?

Thinking either pull the injectors out and get them tested - thoughts on that. Or find injectors that are known to be good and swap to test.

[tree98]

Does it pass a leakdown test? I know it's not making pressure like it should but will it hold constant pressure for 1 minute? If not you need to figure out why, ie. capping injectors/testing relief valve.

I wonder if your problem is a large amount of air in the fuel system. I wouldn't think these pumps could deal with a ton of air for very long before a problem would arise, just a thought.

[Hermjeji]

(07-10-2022 )tree98 Wrote:  Does it pass a leakdown test? I know it's not making pressure like it should but will it hold constant pressure for 1 minute? If not you need to figure out why, ie. capping injectors/testing relief valve.

I wonder if your problem is a large amount of air in the fuel system. I wouldn't think these pumps could deal with a ton of air for very long before a problem would arise, just a thought.

It's not holding pressure. It's got a new relief valve now. Are you saying that, regardless of the max pressure, I should cap the injectors and run the test to see if I can isolate one or many of the injectors?

[tree98]

Yea cap injectors and see if you can get it to hold pressure. Gotta start somewhere.

[Hermjeji]

So - I'm about to quit.
Head #7? Head #8? I don't know. Tested the injectors, and #6 failed the return flow test. Replaced #6 Injector, and saw that the cam was flaking as well, so did that (22000 hours on it). Plugged in insite, it ran fine empty pulling hills. Some information:

1. Fuel pressure commanded would come down when coming out of a pull empty, but fuel pressure measured would keep climbing up.
2. After injector replaced, above was not happening. Climbing a hill pulling about 53,000 kgs, fuel pressure measured and commanded looked like below.
3. Now another day of work, no insite plugged in, and it has started pissing out fuel from the same point on the head again.

Orange is commanded, grey is measured, blue is RPM.


What am I missing?

[amermextrucker]

(08-04-2022 )Hermjeji Wrote:  So - I'm about to quit.
Head #7? Head #8? I don't know. Tested the injectors, and #6 failed the return flow test. Replaced #6 Injector, and saw that the cam was flaking as well, so did that (22000 hours on it). Plugged in insite, it ran fine empty pulling hills. Some information:

1. Fuel pressure commanded would come down when coming out of a pull empty, but fuel pressure measured would keep climbing up.
2. After injector replaced, above was not happening. Climbing a hill pulling about 53,000 kgs, fuel pressure measured and commanded looked like below.
3. Now another day of work, no insite plugged in, and it has started pissing out fuel from the same point on the head again.

Orange is commanded, grey is measured, blue is RPM.


What am I missing?

How do u get to that screen on insite ?