GF-90 Filter question

[Todd Pollock]

I have been dealing with some fuel leaks on my 62 FI unit. I now find that the leak appears to be from the GF-90 filter. It looks as if the front seam of the filter has the leak. Basically where the filter screws in to the FI unit it a dry on the brass nut and the nut shaped part of the filter but the lip of the filter fills up with gas and starts to drip. I am sure the leak has to isolated to the point but is this a common problem? I have maybe 600 miles on the filter. Are there bad reproductions of the filter out there that I should be avoiding? Just curious.

Thanks

Todd.

[Joe L.]

Re: GF-90 Filter question

Todd-----

I don't know of "bad reproductions" of the GF-90 filter. I think that the piece is still available through Delco dealers (although not through the GM parts system) and I would expect that the filters on the market are the Delco-sourced part. However, there are several things that could cause the leak even if the filter was perfect upon installation.

First, the joint between the filter cannister and NPT fitting may have been cracked or otherwise damaged upon installation. This joint is not designed to withstand a lot of applied torque and WON'T withstand a lot of applied torque.

Second, the fittings on the GF-90 filter are NPT-type fittings; they are NOT tubing type, compression fittings used on many later fuel filter designs, especially those for cars with modern fuel injection systems which many modern-day folks are used to. NPT fittings seal at the threads may even require sealer or Teflon tape to achieve a good seal. At a minimum, they need to be sufficiently tight (BUT NOT TOO TIGHT SO AS TO DAMAGE THE FILTER ASSEMBLY). To tighten accurately, use a torque wrench with a "crow's foot" attachment and tighten to the AIM-specified torque value.

[David Van Weele]

Re: GF-90 Filter question

Joe you are correct about the purchase of the filters. I was the first to offer the black painted filter with the screened GF 90. I purchsed and still have some by the case. Some were very rough from the plating, the way they came was silver with red GF90.

[Ed Jennings]

Don't worry about damaging the filter.

Take great care not to overtighten the brass fitting that goes into the top of the fuel bowl. These castings are quite fragile and easily cracked. Very expensive. You could buy a lot of cases of filters.

[Mike L.]

Re: GF-90 Filter question

my question is what is correct for NCRS judging the black GF90 filter or the silver with red lettering GF90? I have a orig. silver GF90 with no lines on the nut ends( inlet or outlet) still in the GM box. Should I put this on??

[Todd Pollock]

Re: GF-90 Filter question

I had just taken the filter off teh other night becuase it was leaking after I just took off the FI unit and put it back on the time with with some teflon paste. I cant find any sign that the fuel is coming from the brass fitting. I ahve used Q-tips around the various parts of th filter to track any flow of gas from the fitting to the filter. Everywhere I rubbed on the fitting and filter was dry. I think I will put of another GF-90 tonight and see if maybe it is the filter.

Todd.

[Todd Pollock]

Re: Don't worry about damaging the filter.

I try to be very gentle on the FI unit. When I got it, it already had a couple stripped screws and I dont want any more damage. I just cant see where the leak may be from. I will try a different filter tonight.

[G B.]

GF-90 now a service design

Earlier this year Delco started selling GF-90 filters that look different from the old design. These new filters have the same inlet and outlet NPT thread size, but they are made of bare stainless steel and have a larger can diameter. The good folks at Delphi thoughtfully include a new stainless mounting bracket with each filter, but the bracket won't clear stock intake manifold casting humps.

I suggest buying your new GF-90 filters from someone who has pre-'02 stock. You won't like the '02 version.

[Todd Pollock]

Re: GF-90 Filter question

I know for the 62's the judging manual calls for a red orange label. I have seen this color on the 63's but am not sure if this is correct and what is needed for other years.

Todd.