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New fuel filter outside sending unit

cmayna

DILLIGARA?
Donator
Here's a pic of my new fuel filter (Napa 3003) which has replaced the sock on the sending unit. It is a 20 micron filter. Between the fuel pump and carb is a standard 10-14 micron filter. Had to cut the hard line 2+ inches shorter, re-bend and then re-flair the end.

4_28_04_10_6_29_10_0.JPG



Here, I never knew this tool existed until I was snooping around ebay. Its a sending unit lockring tool, which makes it so much easier to remove and install the sending unit lockring. A whopping $10 expense. Since I still need to resolve Red's sending unit issues, I see this tool coming in very handy. I forgot to take a pic when I was actually using it on Shag earlier today so I did this mockup showing the tool with the lockring.

4_28_04_10_6_29_11_1.JPG
 
Last edited by a moderator:
The filter is on backwards

























Just kidding :lol

That is a neat little tool though, gonna have to remember that exists!
 
Not to burst your bubble, but I read somewhere not to install the filter on the suction side of a mechanical pump as it has the potential (however small?) to suck/pull the filter material out of the filter and into the line. Just passing along something I read...
 
Tom,
No bubble bursting here. With all the research I have done so far, I have yet to read any reason NOT to do it. The odds of the pump pulling the paper out is pretty remote, especially if you use a semi coarse filter at the tank. At worst case if something happens, it wont be the end of the world to fix.
 
I'm not sure I understand why pulling vs. pushing gas through the filter would make the filter more likely to fail.

When gas flows through an unclogged filter, there will be more pressure behind the filter element (about 5-7 psi over atmospheric with a mechanical fuel pump) and a little less pressure than that after the filter regardless of where the fuel pump is located.

If the filter clogs when pushing the gas, the pressure would drop to atmospheric after the filter but the pressure before the filter would still be about 5 psi more.

If the filter clogs when pulling the gas, the pressure would drop to atmospheric before the filter. The pressure after the filter would drop to a bit (I'm not sure how much) under atmospheric pressure. Would this pressure differential be more than the above case? The slight vacuum might cause some of the more volatile components of the gas to vaporize, but I don't think a mechanical fuel pump can pull enough vacuum to "boil" the gas in the line. If it could, then there would be liquid on one side of the filter and vapor on the other, so I could see how the filter element could rupture.

On the other hand, the more powerful electrical fuel pump for an EFI setup might be able to pull hard enough to vaporize the gas in the line and cause the filter to fail.

Am I thinking about this correctly? Can any engineers/ physicists out there correct me if I'm wrong?

I'm just trying to satisfy my own curiosity, not bash anyone's setup :)
 
"SAC69" said:
Not to burst your bubble, but I read somewhere not to install the filter on the suction side of a mechanical pump as it has the potential (however small?) to suck/pull the filter material out of the filter and into the line. Just passing along something I read...

I've been running one on the suction side of my pump since it was fired up. No problems.
 
"70_Fastback" said:
I've been running one on the suction side of my pump since it was fired up. No problems.


Same here and I actually spend time at high rpm's unlike some of the other grandmas around here.
 
"silverblueBP" said:
Same here and I actually speed time at high rpm's unlike some of the other grandmas around here.

Huh?

oxymoron
1657, from Gk. oxymoron, noun use of neut. of oxymoros (adj.) "pointedly foolish," from oxys "sharp" (see acrid) + moros "stupid." Rhetorical figure by which contradictory terms are conjoined so as to give point to the statement or expression; the word itself is an illustration of the thing. Now often used loosely to mean "contradiction in terms."
 
"cmayna" said:
With all the research I have done so far, I have yet to read any reason NOT to do it.

I'm with you Craig. I have my filter just upstream of the (stock) pump, works great, no probs, and even if there is a problem, it's nothing a quick carb rebuild won't fix...
 
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