Cat C4.4 Acert no start

[mekanik]

I'm posting this here as there is no sno-cat forum. Mods please feel free to move this thread if there is a better spot for it. I am working on a 2012 Prinoth snow-cat. It has a Cat 4.4 Acert in it that was built with no exhaust after-treatment. The unit has 460 hours on it. Its been properly serviced and stored each summer with fresh oil in the engine.

The operator was up on a mountain top plowing snow when the engine quit, it restarted and ran for a few seconds and quit again and would not restart. We went up and checked the simple things and replaced the fuel filters. It still refused to start. There are no fault codes logged in the ECM.

Had the machine towed down the mountain with another sno-cat and hauled it to the shop. We have Noregon J-Pro software to talk to it. Its cranking at 200 RPM 150 is the minimum needed to start. It was making over 5000 PSI fuel pressure while cranking. I pulled the line off the high pressure fuel regulator and fuel was dribbling out while cranking so I replaced the regulator. It makes 8000 PSI now and still will not start.

I'm at a loss as what the problem could be. Does anyone here have any experience on these engines?

 

[partsandservice]

8000 psi should be enough to lite the injectors. Maybe a cam or crank sensor issue. We have had injector driver issues with the larger 6.6 perkapillers engine ecu s.

 

[mekanik]

Thanks! I read somewhere that 3600 PSI was needed to start. I would expect it would log a fault code if one of the timing sensors failed but maybe not.
Both timing sensors are the same I will order a new one Monday and try it in both locations.

 

[Mark250]

hi try disconnecting the primary speed /timing sensor and try

 

[mekanik]

I disconnected the speed sensor on the left rear of the engine and tried to start it with no success.

 

[Mark250]

Not knowing the machine or serial number. Is there a safety shutdown or isolator that may have triggered a no start

 

[mekanik]

There is no safety shutdown system.

 

[mekanik]

Finally found some time to troubleshoot the 4.4 Cat engine. With Noregon J-Pro connected
to it the fuel pressure at cranking speed was 2500 PSI it needs 3625 to start. The pressure relief
valve on the rail had fuel dribbling out of it with the return line disconnected. I replaced the rail
as cat wont sell the valve separate. Now it has 8000PSI when cranking and it still will not start.

I disconnected both timing sensors one at a time and when cranking it shows RPM so I am
assuming they both work properly. The ECM did not log a fault when cranking with a sensor unhooked.

I also ordered a copy of the shop manuals for the engine. I followed the troubleshooting manual no start
chapter and got to where it says to connect with the Caterpillar software and see if the injectors are disabled.
If the injectors are disabled but were not intentionally disabled then install the latest flash file in the ECM.

So if I read that correctly the engine can shut off because of old software in the ECM.
I guess the next step is to find someone with a copy of the Caterpillar software.

 

[mekanik]

We had the Cat dealer send a mechanic to the shop to scan it with Cat ET yesterday.
For some reason when you start cranking the engine it disables the injectors.
He installed the latest flash file with no change. He opened a case-file with Cat tech support.
We will see what they come up with.

 

[JD955SC]

There is an “injection disable” function of a switchable plug in the engine harness. I have had to replace a damaged harness where it rubbed against a support and shorted the wire in question and resulted in an injection disabled code and crank with no start.

 

[Mark250]

hi I picked an industrial engine at random (no serial number)
there is an remote shutdown listed for this serial number. not sure about yours
and it is a normally open circuit. As JD9555C suggested and I mentioned in an earlier post maybe this shut down circuit is compromised somehow.
That assumption is based on 444 prefix engine and may be way off the mark
did the Cat tech leave you with a copy of the product status report and status group?
Having said all that, the remote shut down should of been flagged in ET but stranger things have happened

 

[mekanik]

The Cat dealer come over yesterday and replaced the ECM and flashed it with the latest software. It fired up and runs again.