FF63009 Fuel Filter for Cummins B- and L- Series Diesel Engines Replaces Fleetguard FF63009 | Replaces 5303743 FF63008 FH22168

Correct part fair price.

(The last paragraph below is my most recent review.) We have 2 fuel filters on our Cummins ISL-450 engine. I changed them the first time last week. On the bottom of the plastic can filters is a built-in1" hex knob. To remove the filter, you will need a 1" socket (or 25 mm) to go over the knob and a long ratchet wrench or suitable breaker bar. They will likely be tight. Removal is a lot easier than using standard oil filter wrenches. I prefilled the filter by pouring diesel into the outer holes, NOT the center hole. The filter comes with a cover over the center to make it easier to just pour the diesel into the outer holes. In spite of prefilling the primary and secondary filters and waiting for the fuel pump to prime, the engine still had difficulty starting up. (I did not have that problem when starting our prior motorhome's Cummins ISL-400 engine with standard metal can filters.) Since the above review, we purchased some bad fuel and the fuel filter got slimed resulting in ECM error codes. Not knowing what the problem was and carrying spare filters, we took the vehicle to a Cummins service center. They diagnosed the problem with the clogged filter resulting in high fuel pressures and suggested simply changing the filters and adding a biocide to the fuel. When I showed them our filters and they said that although they were labeled as Cummins, these were not in fact OEM because they were made in China and theirs are made in the USA. As far as function goes, I don't know how these compare to genuine Cummins filters and I therefore have no basis to decrease my original, 5-star view. Since the above reviews, yesterday (10/13/2025), we were stopped by a pickup truck who saw liquid pouring out the back of our motorhome. That liquid turned out to be diesel and it was pouring at at about 1/2 gallon/minute or more. The source of the leak was this fuel filter with a crack under the threaded section on top. I carried several replacements after having problems with some bad fuel, so replacing it was easy, but this has never happened to us before. We must have lost at least 25 gallons of fuel. I don't know if this was due to a manufacturing defect or due to over-torquing it when it was installed (the housing is all plastic and installation is with a 1" socket wrench placed on the bottom of the filter). Since this has never happened before (this is our 4th motorhome), I have to conclude that it was most likely a manufacturing defect. You might be lucky with these, but I cannot recommend using these MIC filters any longer.

If you can find a OEM unit spend the extra money and buy that instead for peace of mind