Primary fuel filter location

[electrician57]

The filter locations I have seen here is not where it’s found ,

inflow line on fuel tank side goes from the lift pump into the passenger side frame and disappears, i have crawled all under the coach and cannot find it. There are no compartment access panels that I can see.is there a panel to remove somewhere? 
Thanks

[RBRODDER]

On my 04 Neptune 36PDQ with a 5.9 , both are on the passenger side.  One is outside of the frame rail and it has the water separator on it the other on was about 3/4 back of the engine and between the engine and frame rail.  I had to be almost directly underneath it before I found it. My coach has a perforated shield that runs from frame rail to frame rail that I had to remove to gain access to the filter. 

[RVSSNAKE]

On our 2000 Diplomat there is a filter on the passenger side of the engine and one in the drivers side bay with air conditioning coils and air dryer. That is a 8.3L engine though. Your 5.9 could be different.

[Bootlegger 659]

What coach are you working on would help many. On my 05 Diplomate both my fuel filters are located on the drivers side in the dash air conditioner fan compartment behind the drive tire. you need the butterfly key to access this compartment.

[electrician57]

1998 diplomat 5.9 ISB 24v

filter is not in the bay with the condenser, hydraulics, power steering resovoir, and air dryer are there.

the fuel line from the tank comes from the passenger side frame rail straight to the lift pump right above the rear axel with only about 2 feet of line visible before it’s hidden in the frame rail.

[Cubflyer]

I can not say for sure, but there is a possibility that the lift pump is sucking fuel directly from the fuel tank.   Personally, I suggest you do yourself a long term favor and install a FASS filters and lift pump system and bypass the factory lift pump.   I did that when I first got my coach and truly believe that had I not installed that system I would have been on the side of the road with an expensive tow and repair bill.  Easy to service filters, trouble free pump and with an output pressure indicator up front to see, assurance that your engine injector pump is getting it's 'life blood' fuel to cool and lubricate it.  Read up on it, I think you will see it's value (especially when you price an injector pump or even the factory lift pump)

Ken

[electrician57]

Thanks Ken

I think that is the most likely scenario, there is no primary filter installed to begin with, the fuel line goes into the frame straight to the top of the fuel tank . I was going to replace the lift pump, that’s when I started looking for the filter, it’s hard to believe that it was built without this filter but it was, it’s just not there.

I was looking at the Fass pump already, now I will install the separator and filter too.

Ken

where did you mount the Fass to the coach?

[Cubflyer]

On 7/12/2023 at 5:37 AM, electrician57 said:

where did you mount the Fass to the coach?

On my 2003 HR Endeavor the original primary filter (the one with the water bowl on the bottom) was mounted in the area where the dash A/C condenser radiator and fan, Air system filter and regulator, and the Hydraulic pump and reservoir for the jack system are.  Drivers side, behind the rear wheel.   I used that filter's mounting bracket and hoses to mount and connect the FASS system.  I had to route a new fuel return hose back up to the front through the conduit pipe and tap into the fuel tank (the most difficult part of the modification.

[Georgia Mike]

On your 5.9 there is a engine mounted canister filter housing only accessible from the top of the engine. I used to own a 2000 5.9 and it was mounted in the same place. It’s a paper filter not a spin on type. The black canister is mounted on the passenger side of the engine block. You should have a second spin on filter for a fuel water separator located somewhere. That could be anywhere along the fuel line. Here is a video on a Dodge Truck same engine as yours.

 

[electrician57]

Thanks for the input, but the engine mounted filter which is plumbed between the lift pump and the injector pump is a spin on fs1253 filter/separator with the drain and water in fuel sensor on the bottom.

1998 24 valve is different than 2000