Got new tank and sender unit and figured I'd look at the fuel lines while I have it out. They're all original, it looks like, so was thinking of replacing them. Was thinking, though...a while back, I removed the emissions stuff up front and capped the return line...is there any reason to keep the return lines back at the tank? Could I just cap them off, as well? Just not sure if they serve any other purpose than returning vapor or whatever.
For the record...if anyone is thinking about tanking their tank out, it's actually pretty easy. Easier than I thought it would be, for sure.
Replacing fuel tank...what else can I do while I'm at it?
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Fiatlanta
- Posts: 184
- Joined: Fri Jul 08, 2016 6:00 am
- Your car is a: 1979 Spider 124
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18Fiatsandcounting
- Posts: 3798
- Joined: Fri Mar 15, 2019 11:23 pm
- Your car is a: 1969 and 1971 124 spiders
- Location: San Francisco Bay Area
Re: Replacing fuel tank...what else can I do while I'm at it?
If you've already capped off the lines at the front, I see no reason why you couldn't do the same at the rear. But, I'm not sure what you gain by doing this?
A question, though: Are you talking about the fuel return line from the carburetor back to the gas tank, or the vapor vent line from the charcoal canister to the liquid/vapor separator in the trunk and then to the gas tank? I forget the exact setup on a '79.
Both have a function, and you can "disable" them by disconnecting but this can introduce other problems.
-Bryan
A question, though: Are you talking about the fuel return line from the carburetor back to the gas tank, or the vapor vent line from the charcoal canister to the liquid/vapor separator in the trunk and then to the gas tank? I forget the exact setup on a '79.
Both have a function, and you can "disable" them by disconnecting but this can introduce other problems.
-Bryan
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Fiatlanta
- Posts: 184
- Joined: Fri Jul 08, 2016 6:00 am
- Your car is a: 1979 Spider 124
Re: Replacing fuel tank...what else can I do while I'm at it?
I replaced the original carb with a 32/36 DFEV, so as far as I understand, there is no fuel return line.
The line that I capped in the engine bay is the line that originally came out of the charcoal canister, which was removed along with the rest of the emissions stuff that I could take out.
I did drill a vent hole in the gas cap to compensate.
As for what I'm hoping to accomplish...replacing the fuel tank now and if there are unnecessary lines, I'd like to remove the lines and cap off whatever ports or whatever that I can. Less stuff, less things that can go wrong. It was running fine for a while, but recently started only being able to pull about half the fuel out of the tank before "running out of gas". Figured I'd just replace the tank and any of the fuel lines while I was at it.
Edited to add:
Looks like you replied to my original post about this issue back when I first posted it. I was inspecting all the lines and all and it looks like everything back there was all original, so might be better to just replace everything once and be done with it. It wasn't that bad of a job to remove everything and get the tank out, but if I can avoid having to do it again, I'd rather do everything together.
The line that I capped in the engine bay is the line that originally came out of the charcoal canister, which was removed along with the rest of the emissions stuff that I could take out.
I did drill a vent hole in the gas cap to compensate.
As for what I'm hoping to accomplish...replacing the fuel tank now and if there are unnecessary lines, I'd like to remove the lines and cap off whatever ports or whatever that I can. Less stuff, less things that can go wrong. It was running fine for a while, but recently started only being able to pull about half the fuel out of the tank before "running out of gas". Figured I'd just replace the tank and any of the fuel lines while I was at it.
Edited to add:
Looks like you replied to my original post about this issue back when I first posted it. I was inspecting all the lines and all and it looks like everything back there was all original, so might be better to just replace everything once and be done with it. It wasn't that bad of a job to remove everything and get the tank out, but if I can avoid having to do it again, I'd rather do everything together.
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18Fiatsandcounting
- Posts: 3798
- Joined: Fri Mar 15, 2019 11:23 pm
- Your car is a: 1969 and 1971 124 spiders
- Location: San Francisco Bay Area
Re: Replacing fuel tank...what else can I do while I'm at it?
The issue with "running out of gas when the tank is half full" could be because the pickup lines are clogged (it happens), or you are building up a vacuum in the tank. You mentioned drilling a hole in the gas cap, but maybe that's not enough if you are really pulling fuel out of the tank. The usual test is to loosen the gas cap slightly and see if that solves it.
You're right, some variations of the DFEV don't have fuel return line. There are many stories about why Fiat put in a fuel return line, but one story is that this kept the fuel circulating back to the tank where it was cooler than the engine compartment, thereby lessening the chance of vapor lock. Makes sense, but the engineers that designed this are likely long gone.
I usually leave the charcoal canister in place because it really doesn't affect performance at all, but it does reduce the smell of gas around the car. And evaporation into the atmosphere.
Hope this helps a bit.
-Bryan
You're right, some variations of the DFEV don't have fuel return line. There are many stories about why Fiat put in a fuel return line, but one story is that this kept the fuel circulating back to the tank where it was cooler than the engine compartment, thereby lessening the chance of vapor lock. Makes sense, but the engineers that designed this are likely long gone.
I usually leave the charcoal canister in place because it really doesn't affect performance at all, but it does reduce the smell of gas around the car. And evaporation into the atmosphere.
Hope this helps a bit.
-Bryan
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Fiatlanta
- Posts: 184
- Joined: Fri Jul 08, 2016 6:00 am
- Your car is a: 1979 Spider 124
Re: Replacing fuel tank...what else can I do while I'm at it?
When it first happened, I got a gas can and put in a couple gallons, but that didn't work...fuel pump was going, but wasn't getting fuel. Loosening the cap allowed the fuel pump to finally pick up some fuel and I was able to get home.
I don't recall what size hole I put in...maybe 3/8"? I'll measure it again and see if I need to open it up some more.
The thing is...which kinda makes sense if we're thinking about clogged lines...is it was running absolutely fine until I let it sit for a couple months due to work and weather...first drive out on a day off in nice weather, this started. So that kinda makes sense.
Fwiw, the charcoal canister and all that stuff is long gone....just working with what I have now.
Thanks again...your input is always very insightful and useful...I enjoy reading your posts!
I don't recall what size hole I put in...maybe 3/8"? I'll measure it again and see if I need to open it up some more.
The thing is...which kinda makes sense if we're thinking about clogged lines...is it was running absolutely fine until I let it sit for a couple months due to work and weather...first drive out on a day off in nice weather, this started. So that kinda makes sense.
Fwiw, the charcoal canister and all that stuff is long gone....just working with what I have now.
Thanks again...your input is always very insightful and useful...I enjoy reading your posts!