DP seems to cut out under loads

[David K]

I once had the same problem with my Cummins 8.3 ISC. The last shop where I had it serviced changed both filters but, they used too small a micron filter for the second filter -- I think it was a 4 micron filter. Cummins recommends that BOTH filters be 10 microns -- I changed out the fuel filters to both being 10 micron filters and no problems since.

[Agaveguy]

I picked up the rig from Freightliner today, they said the Allison 3000 transmission had incorrect calibrations installed from the factory. So they reflashed the trans computer and updated the engine computer with the latest calibrations as well. The service writer told me they did change both fuel filters because of the low power issue but did not say if that made any improvement or not.

I took it out on a 10 mile road test on the open highway and it does seem to have good pickup and power, the real test will be up some hills though.

FWIW, my rig has 15,900 miles on it, I know for certain the fuel filters are not covered under warranty and they did not ask me to pay for their replacement. (Kudos to them!) I am uncertain what the culprit really was in this situation. I'll cross my fingers they have it fixed.

I was happy with Freightliner's service department, they were helpful and kept me informed about the repairs, and over the weekend they put my rig inside the shop to keep it out of the 110f Phoenix heat.

[RIDER FAN]

I had exactly same problem with Cummins ISL 400.Going up hills it would get that dead spot and buck. Putting your foot into it did nothing. Would loose 10 MPH and once over the hill she would slowly gain RPM and away we would go. Restricted fuel problem. Changed filters twice. Ended up being my lift pump.They are supposed to put out mininum of 5lb pressure mine was like 1.5lb pressure. They are a bearcat to change on the ISL.
Now i cruise like i should and going up steep grades the torque converter does it's thing and i have power plus.