Has anyone relocated their fuel filter? I've installed a secondary fuel filtration setup (Caterpillar 2 micron filter) and would really like to relocate the stock filter somewhere on the frame rail so it would see the fuel before it gets to the Caterpillar filter.

The main reason I'm keeping the stock filter and not bypassing it is because it has a water separator. I could buy a separate water separator unit, but how would I go about bleeding the lines if I needed to in the future?

Any thoughts, suggestions?

I have a 2 micron filter setup too, but I installed it before the stock filter. If you move it and something happens, they're liable to tell you that your warranty is voided. I wouldn't take the chance.

I'd welcome any other comments as to whether I could install a fuel/water separator with a bleeder and bypass the stock one all together. I'm not concerned with warranty issues.

PM Frank Blum. I've been using the mount he devised for a Racor under-hood setup for well over a year. He's got pics of the install he can send you to show you how he did it. I posted some pictures of mine on here at one time, but couldn't find the post. You could easily bypass the stock filter that way. You can get them heated, and with water separator if you wish. It's worked great for me.

I have read that the secondary filter needs to be BEFORE the factory one, or like stated above they can attemp to void the warranty.

I have yet to study the stock fuel filter, so I have a question.....does the filter media help separate the water and allow it to drop to the bottom of the canister? Or, does the media just filter?

Another question, does the stock filter heat the fuel?

The filter media does not help to separate the water. The water is heavier, so it settles to the bottom where the valve is. The stock filter does not have a heater in it. The wire attached to it is the water sensor.

The filter media does not help to separate the water. The water is heavier, so it settles to the bottom where the valve is. The stock filter does not have a heater in it. The wire attached to it is the water sensor.

If they do not have a heater....What is the second wire for??

One of the main reasons why I added the Cat filter before the stock unit was to make the stock one last longer. The Cat filter takes care of everything down to 2 microns, so the only thing going to the stock unit shold be particles smaller than that and possibly any water in the system.

The stock filter retails for 3x the Cat. I believe I should get 30K from the Cat filter. I plan to change them both at 30K and cut the stock apart to see how dirty it is. If the stock filter looks like I'm hoping it will, I will increase its change interval even longer.

The Duramax engine DOES have a built-in fuel heater.

This comes from the 2006 Helm's Service Manual [Volume 3, Page 6-3120].

Circuit/System Description
The fuel filter/heater element housing consists of a water separator, a hand prime pump, fuel heater element and a filter element. Fuel passes through the fuel heater, which is operated by a built-in thermostatic switch. The thermostatic switch opens or closes to turn the heater ON or OFF, depending on temperature. Fuel then passes thought the filter and the water coalescer, where the droplets of water in the fuel combine into larger drops that fall into the water reservoir in the filter. When fuel flows to the fuel injection pump, the fuel is clean and free of water.

They also list troubleshooting procedures to determine if it is working or not.

Fuel Heater Inoperative

Circuit/System Testing
Check the Water in Fuel lamp for proper operation. Refer to Water-in-Fuel Lamp Always On on page 8-420.

Disconnect the fuel heater harness connector from the top of the fuel filter/heater element housing.
Turn ON the ignition with the engine OFF.
Probe the fuel heater ignition 1 voltage circuit with a test lamp connector to a good ground.
[If the test lamp did not illuminate repair the short to ground or open in the ignition 1 voltage circuit.]
Probe the fuel heater ground circuit at the fuel filter/heater element housing with a test lamp connected battery voltage.
[If the test lamp did not illuminate, repair the open in the ground circuit between the fuel filter/heater element housing and the engine ground.]
Remove the fuel filter fro the fuel filter/heater element housing. Test the ignition 1 voltage circuit and the ground circuit for an open in the fuel filter/heater element housing.
[If either circuit tested open, replace the fuel filter/heater element housing.]
If all circuits test normal, test the fuel heater thermostatic switch for proper operation. refer to Component Testing in this diagnostic.


Thermostatic Switch - Component Testing

Remove the fuel filter/heater element housing from the vehicle.
Connect the ignition 1 voltage circuit of the fuel heater to a battery voltage source and connect the ground circuit of the fuel heater to a ground.
Cool the thermostatic switch of the fuel heater with ice.
Observe the heating element.
[If the thermostatic switch does not turn on the heater element when the temperature is between -8.4*C and +15.4*C (+16.9*F and +59.8*F) replace the fuel filter/heater element housing.]

Why could I not cut the filter canister open, remove the element, and then reweld the canister back together. That way I still have a water separator and a fuel heater.

I now no longer have to monkey with changing out the stock filter. Why would this not work?

Why could I not cut the filter canister open, remove the element, and then reweld the canister back together. That way I still have a water separator and a fuel heater.

I now no longer have to monkey with changing out the stock filter. Why would this not work?

It's not that easy. The water separator is in the media in the stock filter element; it contains a coating that restricts water from passing through. As for the heater, it is inside the filter housing.

I suppose you could always install a "dummy" filter with no guts and then you will never have to replace it. You'd still have to install a Racor water separator or something similar to make sure you remove any water.

If you have the time, money and know-how, anything is possible. :)

It's not that easy. The water separator is in the media in the stock filter element; it contains a coating that restricts water from passing through. As for the heater, it is inside the filter housing.

I suppose you could always install a "dummy" filter with no guts and then you will never have to replace it. You'd still have to install a Racor water separator or something similar to make sure you remove any water.

If you have the time, money and know-how, anything is possible. :)
Ahhh, I see. I wasn't aware that the separator and heating element was setup like that within the stock housing.

Before I go through the trouble of removing the stock setup and installing a water separator/heater I'll run what I have for 20K miles and will cut the Cat filter and the stocker open to see what it looks like.

I guess if I could go 30K miles on the big Cat filter and stock element then I'm probably doing all of this scheming for no particular reason. ):h

The stock filters are not that hard or difficult to change at all. I would think all that extra work to cut the filter open, take out the media, weld it back together, just to not have to change the filter is too much work! You would also have to worry whether or not you got all of the junk out before you welded it back up. It is much easier to just change the filters at regular intervals and go on. If you have a pre-filter or secondary like the Nicktane, then you have even less to worry about! JMHO!!