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Chrysler LM 318 fuel filter issue

M

michael.stinson

New member
So here I am again asking for more help. I am working on a 1980 Silverton 31 Sedan bridge with twin Chrysler 318's. The previous owner shopped at auto parts stores for his replacement parts. He has Fram FG28 inline fuel filters between the fuel pump and the carb. I had wanted to replace them, not knowing how old they may be, so I went to Intercoastal Marine in Middle River to get replacements. They had only one Fram FG28, but had another make that looked identical, thread and fitting and all. However the non Fram filter, which the previous owner also had several of in his parts bin will not seat properly and leaks no matter what I do to properly seat the fitting.

1) What filter is supposed to be there?
2) As it is a secondary filter in the system is it really needed?
3) Any idea where I can get the proper filters?
4) If it should be the Fram FG28, since they are so difficult to locate, would it be advisable to just change the fuel lines and put in fittings that will properly seat with readily available filters in the market?
 
My 318s have been fitted with the see through type inline filter which I like, because you can see if the fuel is going through. I have also included the inline filter that was stock as per 1975 Chrysler parts manual although the original filter had threaded ends.
 

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Even while carbureted engine fuel pump pressure is limited to approximately 4 to 7 psi, no fuel filter (even w/ metal shell) should be installed down stream of the fuel pump.
In other words..... no carbureted engine fuel filter should be installed within the pressurized side of the system... I.E., between the fuel
pump and the carburetor.
(FI systems.... a different story)

Furthermore, these little in-line filters do not offer much square area of filtration media. In fact, the square area is far to small.

I'd remove them, and use ONLY a Marine Cartridge style filtration system and prior to the fuel pump... not after the fuel pump.

The standard Sierra style uses the filter media to capture water, whereas the RACOR system actually separates the water from the fuel via a cyclonic means.


Metal bowl RACOR = Inboard installations.
See-thru plastic bowl = Outboard installations ONLY.




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Agree 100% with Rick

Only filter after the fuel pump is the one enclosed within the carb fuel inlet.

Go Racor and never look back....
 
.."no fuel filter (even w/ metal shell) should be installed down stream of the fuel pump"

Every car truck on earth is set up that way, as is every Merc OB I've ever worked on.

Jeff
 
What a lunch bag let down. I like the little things and now I am going to have to take tem out. As per my manual they must have been legal in 1975.
 
..."Car or Truck and/or OB ... Apples/Oranges. "

Not really! Think about it.

99.9999% of the time Rick and I are in synch, but not this time.


Jeff
 
Jeff, I agree.... we are in sync more often than not.... but apparently not this time.


Here's the deal.

Pressurized fuel lines that are interrupted with the installation of an in-line fuel filter pose an additional point of potential failure.
The auto industry is concerned, but does not need to be as concerned with fuel leaks as does the Marine industry.... in particular with engines that are enclosed.
Outboard engines are not enclosed.
Auto engines are also not fully enclosed.



I think that if you were to check with the USCG regulations, you'll see that when installed in the pressurized portion of a gasoline fuel line, these in-line filters would not be approved.
Upstream of the fuel pump... perhaps so.

I'm also thinking that the cartridge style Marine fuel filters (for carbureted Marine engines while down stream of the fuel pump) would also not be approved.

Edit:

Ooops..... I may be wrong.
Look here at PDF page 14.... or what they're showing as page #7... figure 2a "a traditional fuel system".

They do show an in-line filter installed after the fuel pump.
If I had more time this moring, I'd look further.... perhaps you can clarify this.

Bottom line for me.....
I have never installed one of these in-line fuel filters, let alone after the fuel pump, nor would I.
Other than the two connecting points that can't be avoided, I do not want anything interrupting the pressurized side of the fuel line.
There's no need for one as the square area of filter media is far too small.
The Marine style fuel filters with a much larger filter media, are more than adequate.

Of course this is my opinion only.



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