Pre fuel filter questions.

[reddie73]

Their is a nylon screen inside the fuel pump where the line from the tank goes to the pump. This screen can get clogged and cause fuel flow problems and I guess it could get bad enough to keep the car from running. Clamp the line from the tank to the electric fuel pump, take the line off the pump and with a small screwdriver or small needle nose plyers take the filter out and check for rust deposits. If you find rust here then your should have your tank sealed. Eastwood makes a kit as does POR-15 for cleaning and sealing the gas tank. You can also take it to the radiator guy.

[FastWoman]

Reddie, I had assumed there would be a screen on the intake of my pump, but there appears not to be one. As I look down the bore of the nipple, it appears to lead directly into the innards of the pump housing, sans filtration. There is no mention of an inlet screen in the FSM. Is this something that might have changed by year? Mine is a '78.

Fortunately my tank is in great shape. There was some soot-like debris from decomposing rubber in the bottom of my tank, but there's only maybe 1 cm^2 of rust inside the tank -- in the deepest part, near the drain plug (obviously where there was a bit of water in the tank). I pressure-washed and rinsed with acetone and B12. I stripped, de-rusted, and acid-etched the outside of the tank and will finish repainting tomorrow.

I think my goal with a prefilter would be to catch any rust or hard debris, but to pass softer/smaller debris like the decomposed rubber. It's the smaller, softer debris I would want to catch in the finer, larger filter in the hood compartment. That way I can dispose of most of the debris with changes of the latter filter.

Gnose, I see plastic Holley ProJection fuel filters, manufactured to go with their ProJection throttle body FI systems (ONLY! -- their emphasis). They're about 1" dia and 4" long. I also see some Holley VoluMax aluminum billet disc filters in various diameters for different flow rates. They come with 28, 60, and 115 micron screens. I'm guessing I'd need 60. Working pressure is overkill (~150 psi). Fuel flow rates are 14 and 35 gpi for the 4" and 6" dia units, respectively. I'm guessing 4" would do it? See here. Of course that's an awfully pretty filter to mount on the underside of my car.

[geoyam]

FastWoman, Have you checked out this Holley prefilter (http://www.holley.com/562-3.asp). Is this the one you're referring to? Holley's website says its to be used between the fuel tank and EFI fuel pump.

Summit Racing has it on their website too (http://www.summitracing.com/parts/HLY-562-3/). Summit's site says it's for the throttle body FI systems.

I have one installed on my 77 280z. It's works fine. It's a plastic inline prefilter with 3/8" hose ends. Essentially plug and play with the existing hose dimensions.

I thought I had the filter specs at one time, but don't recall the micron size. Holley does advertise it as low restriction.

Edited August 18, 2010 by geoyam

[FastWoman]

geoyam, I think that's perfect! Thanks!

[gnosez]

100 microns for the Holley as I mentioned earlier. They also sell the same filter for use on lawnmowers (no EFI)....