C-9 Flames out at low speeds

[Bob Dunlap]

Our 06 Beaver Monterey Venture IV has a new C9 engine (courtesy of Cashman Cat in Las Vegas) as of December, 2017.  In the last year, at very low speed (stop & go traffic) upon acceleration, the rpms would drop and the engine would die.  I would have to turn the key off, then re-start and it would be fine until the next slow speed condition.  It has good power going up steep hills and no problems accelerating from a dead stop.  It doesn't matter if the outside temp is hot or cold or if the engine is hot or cold.  Our local shop had a CAT mechanic diagnose the problem as low fuel injection pressure. They said this could be caused by dirty oil or bad oil filters, but I had just had the oil and filter changed before that trip.   They drained the oil, flushed the system, replaced the filter and filled with fresh oil.  The same thing happened and the same code appeared.  They replaced the ICP sensor and said if it happened again that I would need to have a high pressure oil pump installed.  On a trip through Los Angeles Traffic, it happened again.  Real leg-wetter.  We were in the middle of a 5-lane freeway and were barely able to make it to the shoulder.  It wouldn't restart.  After 10 or so attempts, I decided to start the generator to keep the batteries charged.  When I tried to restart the engine, it started.  Maybe is was not an oil pressure issue at all?  Might be electrical? We've had the power solenoid replaced and both chassis batteries replaced.   It happened several times again after that.  When I took it to my trusted mechanic in my old home town, he couldn't find anything wrong but suggested I double the amount of Diesel Kleen in added to each fill up.  I did that and haven't had an issue since.  Any thoughts on what might be going on?

[Joel Ashley]

Dirt or algae in the fuel tank perhaps.  The mechanics replaced the oil filter but not the fuel ones?  I’m no diesel mechanic, but it sounds like not enough pressure from the pump upon sudden demand.  I use Power Service’s Clear Diesel and Bio Kleen and have had no issues fuel-wise.  There is an additional fuel pump add on procedure also, that some have had done, and that our club’s “in-house” CAT mechanic, Dave Atherton, has espoused.  There may be a discussion of that in the Club’s Coach Assist section (see “Technical” menu on the Club’s main home page).  I’ve not had that extra pump added since our short, lower weight chassis has not had power problems.

Joel 

[Eric Maclean]

Bob
Do you know what the code was that the shop diagnosed the ICP sensor from and does this code return each time the engine quits?
If it does the code is pointing to low ICP ( injection control pressure)
And could be one of several things the sensor merely reads the high pressure oil in the cylinder head rail which is used to fire the fuel injectors
This high pressure oil is supplied to the cylinder head rail from a high pressure oil pump known as the HUEI pump this high pressure is controlled by
ECM controlled solenoid valve which the ECM duty cycles to vary the rail pressure from approx 1000 psi to several thousand depending on engine load
In this way the ECM can control how much fuel is delivered each time it commands an electronically controlled fuel injector to fire.
There are several faults that can cause low ICP .

1)failing HUEI high pressure ( not building enough pressure)
2) poor or failing ICP solenoid valve ( not controlling rail pressure properly)
3) bad ICP sensor ( sending false reads to ECM)
4) leaking 0 ring on one or more injector ( resulting in lower than command ICP pressure)

A mechanic will a Cat scan tool and cat et soft ware should be able to read the ICP pressure through the ECM and get a better idea of whether or not the pressure is dropping out at idle .he can also command ICP pressures through the scan tool to verify if the ICP solenoid has control of the pressure.

If it is one or more injector o rings failing it will eventually get to the point where the system can't produce the minimum 800 psi at cranking speed to actually fire the injectors and start the engine.

With the valve cover removed and the engine idling you should be able to see oil squirt up beside a injector if the o ring has failed.

As Steve stated Dave Atherton has been a CAT mechanic for many years and could be a great help to you to get you pointed in the right direction
He can be reached through the BAC Web site

Hope this helps
Eric

[Steve Huber Co-Admin]

Input from Dave Atherton; First check the key ring weight as significant weight can cause the ignition switch to intermittently fail and cut power to the ECM. There is a CAT service bulletin out on this. It could also be the Injection Actuation Pressure Sensor or the Atmosphere Pressure Sensor starting to fail. Both sensors are 5 volt and share the same signal wire from the engine ECM.
Steve