Fuel filters

[Cj D]

Interesting, as I was the opposite. No information is in my manual about changing the filters, except "when" to do it. The first change I did not fill the filters, and the rig would not start. I called Monaco and he told me I was supposed to pre-fill the filters. I did, but still no start, and Monaco had NO advice, LOL. That's when an old diesel mechanic told me to pressurize the tank. If you notice, all the over-the-road trucks have cylindrical tanks, so pressurizing them does not risk "popping" the tank like in our square-tank RV's.

Once I pressurized and bled the lines at the fuel rail, the rig started right up. I then started pre-filling the filters, and only one other time had trouble...where the rig started, but then stopped. That's why I recommend revving until you get all the air out.

[ppine]

You can fill them with fuel, or you can turn on the ignition but not start your rig several times and let the fuel pump fill them.

[wolfe10]

As I described in my post on 12/20, if the level of fuel in the tank is lower than the filter head, when you removed the filter element, all the fuel in that 30'+ of fuel hose will drain back to the tank. That leaves you with 30'+ of AIR that needs to be purged from the system.


Basically if fuel did not run out of the filter head when you removed the filter-- it ran back to the tank.



Do not assume the fuel pump is bad. You should hear it running for 20 seconds or so when the key is cycled on. If so, it is working.


The suggestion about adding low pressure air to the tank fill to force the fuel from tank to primary filter is the solution to purging all that air.


PERMANENT, LOW COST SOLUTION:
Install a diesel-compatible ball valve on the inlet to the primary fuel filter. Turn it off when changing filters. No fuel will run out OR back the tank.


Oh, and that is a heck of a theft preventer!

[Cj D]

I do not know about the newer rigs, but as described above, the fuel route for all the older rigs is tank to chassis filter, then uphill to the lift pump, which is a tiny electric pump between the ECM and block, and then to the block filter, out to the mechanical fuel pump, and then to the fuel rail.

When you pull the chassis filter the lines will drain. If you install the filter dry, then the large air bubble will cavitate the lift pump. It will not pump air, especially when it has the high pressure pump behind it. If you are lucky, and cycle the lift pump many times (without lubricating fuel in it)...you MAY be lucky enough to get the rig running. It is hard on the pump and needless, though.

I did not mention, but after 3-4 dry filter changes before I knew better, my lift pump died. The rig will not run without the lift pump.

Now...a worthwhile mod may be to add an additional boost pump near the tank. That would push the fuel to the lift pump, instead of the lift pump having to suck air and fuel. Then you could dry change the filters all day with no starting problems!

[cbr46]

Not sure now where I read it (Cummins Owners manual?) . . . . Pre-fill the Primary filter but DO NOT pre-fill the Secondary filter.

If the diesel is contaminated in any way pre-filling the secondary filter, especially if you're confused which end (inside / outside) to fill, could allow contaminants to the injectors. That secondary filter is a 10 um filter, or 0.04 thousandths . . . . pretty darn tiny.

Would you risk it?

So my advice is to pre-fill the primary filter, briefly start the engine, replace the secondary filter DRY, cycle the ignition key 5 times, 30 sec each time. Try to start. No start? Cycle the ignition 5 more times and attempt to start.

I ran out of fuel once in middle Alabama, after driving non-stop from Tulsa OK. Walked to a Love's and carried 8 gal of fuel back to the RV. Talk about heavy . . . Got it started but only made it to the beginning of the exit ramp 1/2 mile away. Went back to the Love's and got 5 more gallons. RV stopped again at the entrance to the Love's. I was on flat ground so I felt the pickup was getting fuel. Sucking the tank dry I probably clogged the filter. So in the turn lane I crawled in and changed the primary filter . . . . no pre-filling! It probably took a dozen cycles of the ignition key before it started, almost no fuel and a dry filter but it did start. Limped into the Love's and got fuel. What a waste of 2 hours that was!

I wish I'd kept that old filter, but the last I saw it was airborne into the weeds.

- bob

[ppine]

Do not buy fuel filters on Amazon. I got some that looked like Mopar but they were Chinese fakes. One did not fit and the other one fell apart.

[Timaz]

I've bought filters on Amazon including FASS filters. You just have to investigate/check out the store you are buying them from.

[Surf Fisher]

Many years ago I used to have Speedco do my engine service. They always removed both fuel filters, prefilled the new filters and had me start the engine from the rear with the remote start in the engine compartment.

It had always fired right up and ran like a well oiled sewing machine.

The place where I now have my engine serviced also prefills the fuel filters without ANY difficulty.

I think those who service their own filters are not quite as diligent and end up with problems.

[Qui-Gon John]

I have a gasser, 2006 Winnebago Aspect 26A (Ford E-450). I changed my fuel filter about 2 years ago. Did not do anything about filling the filter and had no problem. Maybe because it's gas vs. diesel.

[Lowflyer1]

Originally Posted by Qui-Gon John

I have a gasser, 2006 Winnebago Aspect 26A (Ford E-450). I changed my fuel filter about 2 years ago. Did not do anything about filling the filter and had no problem. Maybe because it's gas vs. diesel.

Yes, in the fuel injected engines the fuel pump is in the tank and it is continuous flow, so you don't get into a situation with air pockets or sucking air.

[OMMM4747]

Hopefully you have fixed your problem by now. If not, then you have air in your fuel system that you haven't been able to purge.

Watch this video:

https://www.youtube.com/watch?v=i0Dw...llerIndustries

I'm not a mechanic, but I'm guessing the concept and process is very similar regardless of the type engine or manufacturer. The only difference would be whether or not yours has a lift pump (determines whether or not to prefill the secondary fuel filter).

1. Check your work. You will need to start from the beginning.
2. Are the rubber seals installed correctly/not twisted, lubricated? A poor seal will suck air and not fuel.
3. Are the filters on tight w/a good seal; no air getting into the system?
4. Is your primary filter/fuel-water separator full?
a. If yes, you likely have a lift pump since turning the ignition key primed the primary pump
b. If no, then you either have an air leak (not well-sealed system) and/or don't have a lift pump or it’s not working
5. Pull the secondary filter, is it full? See 4a. and 4b.

Presuming you've checked your work and followed the video's guidance to reinstall everything and ensure a good seal. With a partner, have them turn the ignition to start but do not crank the engine while you watch the primary filter and listen for the pump.

1. Does fuel/water separator start to fill?
a. If yes, continue with the video's guidance.
b. If no, did you hear the pump?
i. If yes, the pump is working.
ii. If no, try to find and check the pump. Some have thermal breakers that will trip if the pump becomes overheated which would be the case if you have run the pump numerous times w/air vs fuel (fuel serves to cool the pump). If no luck you may have to replace the pump. If the pump is running but the primary filter is not filling, then you have an air leak (not well-sealed system).

The next question is the secondary fuel filter and whether or not it should be prefilled??? Unless you can determine with certainty whether or not you have a lift pump (have your engine model & serial number and call the manufacturer), I'd start with an empty secondary fuel filter (like the video). Go through the priming and starting process and hope for the best. If still no luck, pull the filter again, fill it and try again.

If after all this is done you're still not having success I'd start w/a mobile mechanic vs getting a tow to a repair facility. Note: the mobile mechanic will be familiar with the concept and process for changing filters and not the procedure specific to your engine and why I feel you should be able to figure this out. But if you do go with a mobile mechanic, watch the entire process and ask questions so you will know for next time. AND please share so others may learn.

BTW, I don't have a Cummins X-15, but successfully used this video to do my filter changes.

Good luck!