Gray Coating on Paper Fuel Filter

Technical and Repair Discussions
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Forum Hermit
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PostPosted: Sun Jan 08, 2012 12:59 pm
The last two times that I've changed my paper fuel filter, I've found a thin gray coating on the outside of the element. It's a smooth, uniform coating over the entire element that easily scrapes off as an extremely fine powder.

Before the previous change, I had been using Sunoco 260 GTX (98 octane, no oxygenates) exclusively. Before this most recent change I've used both Sunoco 260 GTX and 93 octane oxygenated "pump" gas from both trackside supply and public gas stations (no generic stations: Shell or Exxon only).

It doesn't seem to impact fuel pressure. (I have a dashboard pressure gauge upstream of the filter and a logged sensor downstream of the filter.)

Anyone else seen this?

Ed
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PostPosted: Mon Jan 09, 2012 6:25 am
Ed,
I presume you see this after letting the filter completely dry? I don't think I've seen this before.
Do you have a "pre-filter" between the tank and the paper filter?
Denny
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PostPosted: Mon Jan 09, 2012 12:24 pm
Hi Denny,

The outside of the filter element appears gray even when it's fresh and wet. After it dries, the coating can be scraped-off easily.

I have a pre-filter upstream of the pump. It's a cone shaped, fine mesh, metal screen. I've checked it at the same time that I've changed the paper element. It's always been clean.

I should mention that prior to these last two checks, the filters had always been checked and replaced by the guys at Spec Racer Sports. When I noticed it the last time (which would be the first time that I had changed the filter myself), I showed the filter element to them to see if they had seen it before or knew what it was. They said that they had not seen such a coating before.

Ed

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PostPosted: Mon Jan 09, 2012 1:57 pm
it's that special gas you are using, Ed.

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