Fuel Filter on 12 Valve B5.9

[Mike Canter]

Well when your power at wide open throttle drops off and you still have boost and your EGT goes down it is probably the fuel filter blocked. I only had a little under 20,000 miles on that fuel filter so I didn't expect trouble. I must have picked up some bad diesel which blocked the first fuel filter. Thought I had lost the turbo because the motor was holding itself back under full load but the boost still showed 30 psi but my EGT dropped to 1200* because I didn't have enough fuel. It was nice to know I had spare fuel filters with me. I am going to cut the fuel fi;ter open when I get home and see what blocked it.

[Mike Canter]

Well when your power at wide open throttle drops off and you still have boost and your EGT goes down it is probably the fuel filter blocked. I only had a little under 20,000 miles on that fuel filter so I didn't expect trouble. I must have picked up some bad diesel which blocked the first fuel filter. Thought I had lost the turbo because the motor was holding itself back under full load but the boost still showed 30 psi but my EGT dropped to 1200* because I didn't have enough fuel. It was nice to know I had spare fuel filters with me. I am going to cut the fuel fi;ter open when I get home and see what blocked it.

[FD5]

I change my fuel filter every 10,000 miles.

[Mike Canter]

Well, I get almost all my fuel from Flying J and every pump seems to have fuel filter on it so I figured I could go longer. Maybe there are no guts in those filter canisters and I am being fooled (lol). I will know more when I get home and cut it open. I keep my tank full when it is at home and I run it enough that I am get a complete change of fuel in the tank. I have never drained the tank so maybe I need to do that.

[SargeW]

You are running at *1200 on a 12 valve
As I recall that is about the max for the 12 valves. The 24 valves EGT jumped to about *1450. But they had oilers under the pistons to keep them cool. You running some sort of box??

Sarge

[WA4SLC]

I have had 2 Dodge Rams with the Cummins engines, a 2001 and a 2004.5. The maxium mileage that Dodge recomended for a fuel filter change was 15000. I usualy changed mine at 10000 miles or less. It is cheep insurance to change them early, because the openings in the injectors are so small that they can become cloged then you have a big repair bill. I usualy get my filters for about $15 and change them myself. It is not hard to do.

Bill

[Mike Canter]

Sarge. 1300* on the EGT is where max power is on all diesels. The 12v motor comes from Cummins with EGTs going somewhere around 1350 to 1400*F which is too hot. The Banks Power Pack unit that I have also has a EGT and boost gauge and Banks wants the temp right at 1300* at full throttle and full load and it is adjusted for that. Also EGTs on a fully loaded motor that is being lugged because it hasn't downshifted should never get above 1350* and that is why it is important to downshift if the RPMs starting dropping too much gouning up a steep hill. Diesels are opposite to gas motors in that EGTs on a diesel go up when the motor gets more fuel and the EGTs go down when fuel is taken away. Gasoline motors are opposite and EGTs go up when you lean them out or go down when you add more fuel to cool them off.

Bill, it was only the primary filter that blocked up. The small secondary was still doings its job so no dirt got through to the injectors. I changed both of them at a roadside rest area in Texas and drove home today without any problems and more pep.

[Ray,IN]

Keeping clean fuel filters on a diesel engine is paramount to a long-running dependable engine. Don't forget the fuel heater screen when changing filters. If badly clogged, the screen is replaceable. Another often-overlooked problem area is the flexible fuel lines between the fuel heater and fuel lines to the tank. The inside can deteriorate, collapse, and starve the fuel pump. All this while the exterior of these fuel lines appear fine.

[Skipper 05MA]

I'm running a 400 ISL in a 05 Mountain Aire. We usually go to Spartan anually in the Spring for engine and chasis service but we took a trip in Feb 09 of about 2000 miles and I notice some power loss on the way back home. The filters have about 8000 miles on them but the coach was in storage for about 3 months just prior to this last trip. If I change the fuel filters on my own how big a deal is it? Anything to watch out for? ie, pressure, etc. Thanks

[Ray,IN]

Mike Canter, this website should help understand normal operating EGT, maximum EGT, etc for the Cummins engine. Any time EGT(pre-turbo) is allowed to exceed 1350* for more than a few minutes, internal engine damage is occuring.

[hillboy]

Some believe that the fuel filters have a "shelf life" and on an RV it makes sense to change every year. Seemed like an easy thing so now I do a yearly change. Not expensive.