1975 280z installing a G-3 fuel prefilter

[Dave WM]

Maybe this has been covered a bunch but here is my attempt and installing the filter.

1st the reason why, my tank was renewed and a the time the prefilter sock was NOT replaced, so I have a open tube for the pickup.

So the G-3 fram filter was picked to go between the tank and the pump inlet.

1st problem was fuel hose sizing, I think I had used either 1/2 or 7/16" fuel hose originally for the tank to the pump. the 7/16 seemed way to big to fit on the 3/8 filter inlet. I did not trust the hose clamp to make up the difference, perhaps it would but I wanted to try something different. So I am in the process of heat molding some 3/8 line over a 1/2" mandrel by heating up the hose, lubricating the mandrel and slipping it over then heat again and again and again. This is just an experiment as I like to try things and see what happens. So far the molding seems to be working and I don't think I am damaging the fuel hose (its not under pressure anyway). I am going to keep at it and see if the molding will retain its shape enough to install on the tank without stressing out the tank outlet. If it looks like its going to be too hard to fit I will go back with the 7/16 and just hope the clamp will make up the difference on the filter.

[Zed Head]

Most people stretch the 3/8".  8 mm is super close to 5/16" (.315" and .3125"), but 10 mm is between 3/8" and 7/16".  .375", .393", and .437". The basic problem is is that they're metric sized fittings.

Can't you just lube it up and press it on?  Or is the filter nipple too big?

[Dave WM]

It fits the filter nipple ok, its the tank that was the issue, IIRC it was way to big for the 3/8 at least seemed to be at the time and I really do not want to try to hard, BUT that maybe because when I 1st started working on the car I was such a newb to such things that I don't think I tried to lube it up. Perhaps it would have been fine, esp since others have been doing this as you note with the 3/8's. I will give it a shot tomorrow with my modified line, while under there I plan to change out the diff oil as well. I have already loosened both the filler and drain plugs.

[siteunseen]

For what its worth I use Fram G2s on my 240s. They have smaller nipples.

[Chickenman]

Yeah. I remember installing the G3 was a PITA on the fuel tank side of my 280z. Eventually got it by making up a new length of hose, heating the hose with a hot air gun and using lots of Silicone spray. I assembled it off car as well. Clamped the hose in a vice, hot air gun, taper punch to enlarge fuel line, then blasting everything with Silicone Spray. Lots of grunting and swearing involved...

Edit: I remember looking at the G2's and I don't think they'll work on a 280Z. The fuel pump inlet side fitting is too big. You don't really want to use a Fuel Filter with smaller fittings either because it will restrict the FI pump inlet and cause a pressure loss or overwork the pump. The higher pressure that the FI pump generates require a larger inlet hose from the tank otherwise you can get pump cavitation.

Edited April 27, 2016 by Chickenman

[Dave WM]

I got it on last night, the slightly enlarged 3/8 fit on the tank well, did not require any herculean efforts to get on. Of course doing this at night without getting the jacks out, turned out to be a less than ideal setup (full tank of gas of course). Garage still smell of fumes, but its done so one more check on the to do list.

I did notice a lot of air trapped in the filter, I guess all I have to do is tilt it pump side up to purge the air that is trapped.

[ramsesosirus]

FYI when I did the G3 filter, I used a few barbed connector adapters.  This way I could use the appropriate sizes for each, then transition them using the barbed adapters.   Basically like these:  

And made sure all clamps were tight.  Several years later and it's still good, no leaks (OK, no leaks from these, but I am chasing a fuel tank/sending unit leak that is unrelated... )

Edited June 2, 2016 by ramsesosirus

[Dave WM]

Did not even think of that, good idea. Funny thing, I too was chasing a fuel leak. Seemed to come and go, figured it was the sending unit as I noticed it with a full tank. At 1st I could not see any problem with the O ring, but closer exam showed very fine cracks. Replaced it and that stopped the full tank leak. Next it was a leak that happened all the time but this time it seemed to originate at the fuel drain plug. The fuel drain being the lowest point was where the 1st leak showed up, but this time it was dry all around except at the fuel drain. Turned out the little washer had a crack in it as well. I found an o ring that fits but that is temp until I can get down to a hardware store more a more perm fix. Will also coat the thread with some sealant next time its empty and replacing the washer.