Combine diesel purge with fuel filter change?

I was looking at my new fuel filter and the diesel purge bottle thinking how close to the same size they are.

Can you prime the fuel filter with the diesel purge and just drive it after you are done?

Yup. I used DP to fill my fuel filter when I changed my fuel filter last time.

I have been doing this every time now. It seems to prime better than using bio or anything else too.

sure, you can do this, but you will only extract a fraction of the potential benefit of using DP. If you just prime the filter and drive off, a tiny bit the pure DP will go through your injectors and then back to the fuel tank to be quickly diluted with the tank contents.

For maximum benefit, you need to temporarily replace the fuel tank with the can of DP. then all of the fuel that is recirculated will remain pure DP and you will cycle this through the injectors over and over again. This provides the most cleaning action.

I can't think of any reason why one diesel fuel (or additive) would prime better than another.

Now that I think about it, I used PS to fill the fuel filter, not DP. Only because I had no other fuel available to fill it with.

Does the majority of the return line end up in the fuel filter or back in the gas tank? How much of the return line branches off into the fuel filter at the tee?

I would have expected most of the circulation to be in a loop between the engine and the fuel filter while the supply line from the tank only contributes about as much fuel as is actually being consumed by the engine.

when I use DP the way I've described, the return tube is continuously re-filling the can. This tells me that most of the fuel returns to the tank. This is why it takes so long to empty the can of DP.

And there is a picture right in the Russell Parr HOWTO of what you describe with a healthy return line to gas tank flow now that I look again. Rather than using a separate filter, he goes through the main fuel filter and replaces the gas tank with a two bottle DP dose.

Oh well, I'll get it right next time. The one consolation I have is that I shut the car off a few times while trying to fix a leaky tee so hopefully the DP got to sit in the injector pump and injectors for a while.

I think the flow partitioning is temperature related. More directed to the filter when cold than hot. Not sure of actual ratios though.

Don't forget to change the oil after the Diesel Purge treatment. The DP is supposed to contaminate the engine oil.