Fuel filter before or after fuel pump or both?

[Hvnfn]

Hello!

I was thinking about the design of my fuel system... more like looking at all the hoses to replace, etc... when I noticed that the fuel filter was placed before the carb, just AFTER the fuel pump... It seems to me that the filter should go on the line BEFORE the pump, on the firewall side, such that stuff from the tank doesnt gum up the pump... two filters, one before the pump and one after seems overkill, but I will ask anyhow... Where do you recommend placing the filter(s) and why?

Please forgive the basic nature of this question, but I am learning as I go and it never hurts to learn!

[baltobernie]

Sounds like your car is about the same vintage as mine (1973).

There are two filters; one fine mesh screen at the pickup, and another filter before the carb. The screen in the tank keeps the big debris from ruining the pump. Mine was a brass "sock" and had disintegrated. Easy to pull the sender and have a lookie. Does your fuel gauge work?

FWIW:

• ∙ 5/16" line can be used most everywhere, except you will need some 1/4" for one line in the trunk and in the engine compartment. The big vent line in the trunk can use 5/8". All told, about 25 feet of assorted sizes.
  ∙ don't forget the hose from the filler to the tank. removal of the quarter panel makes this possible, but its still a bitch to wrestle this short, big hose into position.
  ∙ are you replacing hoses due to fuel smell? If so, you have a big decision - what if it's the tank? I rationalized that the extra effort wasn't worth the gamble, so I pulled the tank and treated it with a POR15 product. no more smell; don't know if the tank leaked or not, but that's one less thing to worry about.
  ∙ BTW the steel lines in the system can leak, too

[Hvnfn]

Hiya!

Thanks for your reply!!

I am running a '79 2000 spider and I am in the process of taking off the crappy stock intake/carb and replacing both... while I have it all off, I am replacing all of the hoses under there at the same time! I forgot about the sock filter at the pickup... so, there are two... ok.
Lucky enough, I replaced the sender stuff about 6 months back to get the fuel guage working again... cool... interesting enough though, there is another UFO looking doohicky in the line just before the pump... (from the tank to the pump...) similar looking to the UFO thingy in the line before the carb... Is this a check valve? That definitely needs to be replaced/removed.

My crankcase breather tubes were both toasted... in some places, completely disintegrated... so, vualla, some noise and smell will come from that... so, replacement is definitely warranted!

As for smell... The fuel smell in the trunk is pretty heavy, but I dont really smell anything but exhaust in the cab... which comes from the crankcase breather tubes and possibly a leak at the gasket on the exhaust manifold... The exhaust likes to come through a nice open inlet tube on the passenger side of the firewall... I would be interested to know why that is there... A/C maybe?

Anyhow... I am replacing the manifold/gasket as well, When I can find a 4-2-1 manifold and downpipe.

Thanks a ton for the line sizing info, I was wondering about the size of line they used... I would like to use steel braided hoses for the fuel lines in the engine bay... I was also going to replace the nasty cloth lined hoses at the fuel tank... I think the metal lines are probably ok, but I will plug the line at the tank and push some pressure through the line to see if there is a leak...

[baltobernie]

Be careful with your doohicky!

Suggest you cut the fuel hoses a few inches from the body, and remove the check valve to your bench, where you can carefully cut the remaining hose loose. Thirty-year-old plastic that has been in contact with fuel is very brittle. I just bought a salvage piece from Bayless; learned the hard way.

[mbouse]

all current owners of flying saucer shaped doohickies.... beware....

your doohicky should be removed and discarded. back in the day, Fiat discovered that this doohicky (check valve) generally failed and caused engine bay fires. Fiat issued a recall notice, which stated that the check valve be removed and not replaced.

and, yeah. that menagerie of black hose in and around the gas tank amounts to roughly NINE foot of hose, and requires 14 hose clamps to replace.

[Danno]

BTW, I have some hose. If you decide how much of each you need check with me before you order or go buy some. I'm not looking to make any real money on the stuff, just clear some space in my parts bins. My hose is not metric, and is what I used on my 2L, so it should work for you too.

[baltobernie]

all current owners of flying saucer shaped doohickies.... beware....

your doohicky should be removed and discarded. back in the day, Fiat discovered that this doohicky (check valve) generally failed and caused engine bay fires. Fiat issued a recall notice, which stated that the check valve be removed and not replaced.

and, yeah. that menagerie of black hose in and around the gas tank amounts to roughly NINE foot of hose, and requires 14 hose clamps to replace.

Mike, is this the offending part? I have a vacuum leak somewhere in the vapor recovery system; replaced this with a salvage part from Bayless, but not sure if I installed it in the correct orientation. My Haynes manual no help. Anybody have a "theory of operation" or diagram of the vapor recovery system used in our cars?

[mdrburchette]

Aren't you fellas talking about the device at the carb? The 3 way valve in the trunk is to let fumes pass to the canister.

[baltobernie]

Looks like we were talking about two different things, after all. I'll re-post

[NickSpider]

pictures of what you guys are talking about would be helpful for us newbs.