Cummins ISl 400 stutters on inclines - fuel pump issue?

[BobButerbaugh]

Greetings Forum folks!

We are having an issue with our Cummins ISL 400 engine bucking on inclines. On level and downhill roads, the engine runs great. Mileage is 155,000. All filters and fluids were replaced at 144,000.

The fault codes that appear repeatedly on the diagnostic screen include:

Fuel pressure change
Injection valve fault
High fuel pressure
Fuel pump controller fault
Lift pump fault

We took it to Cummins in Boise and they wanted 10K to replace the fuel pump and told us it could be a month before they get the parts. We think Cummins is out of their minds. Are there other things we should investigate before replacing the entire fuel pump?

We plan to find service in Portland OR, and are currently about 200 miles from our destination. Any suggestions for a reliable diesel guy in Portland would be appreciated.

Thoughts?

[Marty and Suzie Schenck]

Since you have 10,000 miles on filter changes, try changing the fuel filters. Both of them if yours has 2. You could have got a bad batch of fuel somewhere in your past travels. This is something that costs the least and you could do yourself if desired. Marty

[BobButerbaugh]

We were thinking to replace the filters and see if there's a difference before spending an arm and a leg on a fuel pump. We'll try it. Not sure about the fuel, though it did start after we refueled. We just refueled again, so we'll see if it abates. Thanks again!

[Eric Maclean]

Bob
With out fuel pressure reading from the common rail it's hard to make a good diagnoses the fact that the system is throwing a fuel pressure too high code would tell you that the high pressure pump is capable of a higher pressure that the ECM is demanding.
On a Cummins common rail system there is a mechanical lift pump which supplies fuel to the high pressure pump at about 70 psi from there the high pressure pump ( a twin piston pump ) boosts the pressure up to between 3000 and 29000 psi to the common rail for each of the injectors.
The fuel pressure is controlled by the ECM via fuel pressure actuator located on the high pressure pump this is a duty cycled fuel solenoid which the ECM uses to control the rail pressure the ECM monitors the rail pressure at the rail with a fuel pressure sensor located in the center of the fuel rail if for some reason the fuel pressure gets too high the rail also has a fuel pressure relief valve which Cummins calls a regular at the far end of the rail which will dump the over pressure back to the tank or return line.

In most cases the system will develop leaks in the fuel transfer tubes inside the head which connect the fuel lines from the common rail to the injectors when this happens the fuel is leaked into the return passage inside the head and returned to the tank resulting in a lower than commanded fuel rail pressure and triggering a internal fuel leak code and sometimes before the fuel leak code is set you will get a fuel filter pressure differential code.

In your case the ECM is reading a rail pressure higher than commanded which would indicate the fuel pressure actuator located on the high pressure pump is at fault .
If you read each of the codes knowing now how the system works you can see each of the codes points to the fuel pressure control circuit which is that fuel pressure actuator on the pump in conjunction with fuel pressure sensor on the rail.
The codes indicate the ECM has lost control of the fuel rail pressure.
At this point you need to confirm the rail pressures .
My guess would e a bad fuel pressure actuation solenoid on the high pressure pump.

Hope this helps
Eric

[Dave Atherton]

Good morning, Eric has described in very good detail about the high pressure common fuel rail.
I would like to add with Connect Cummins Insite into the engine ECM the problem with what is
causing the sputtter is the ( return fuel pressure regulator not seating on the common rail ). How
To determine the return fuel regulator is causing the problem have a experienced technician remove
discharge line on regulator with engine off. Than restart engine with fuel line removed, pay close attention for drops of fuel ( I believe off hand more than 8 drops of fuel coming from open line will
Indicate the return fuel pressure regulator is bad and needs to be replaced. The last one I replaced
Cost around $ 426.00. Dave Atherton Retired Cat Mechanic

[Dave Atherton]

Gentlemen, forget to add point to my last post. When I mentioned with checking fuel return
pressure regulator with engine running ( approx 8 fuel drops per minute would indicate bad
Regulator). In addition to why the regulator leaks and does not seat, the fuel fines not caught
within the fuel filters will settle within the regulator. Dave