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TR3A under tank fuel filter

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templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
Found this old plastic inline fuel filter under the tank above the drivers side shock mtg plate. Not original, from what i have gathered not uncommon, but is it a good idea? Can see pluses and minuses here. If yes, obviously metal filter and need to get it back in factory clip. If not, bend steel line or braided rubber fuel line. Thx

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charleyf Silver Member Charley Fitch
Redding, CA, USA   USA
1962 Triumph TR4
1963 Triumph TR4 "MR.T"
Temple,
The conventional wisdom is to put a filter after the fuel pump. Yours is before the pump . I have one just before the carbs.
Charley

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
Appears I have both, decided to remove in line under tank and stay stock. Don't like the placement anyways. Looked again for a fuel pump some where, nope. Stock style mechanical fuel pump/filter in place, haven't touched since I first flushed fuel system. Only question is what type fuel line to replace with. Right now, either bend some new tubing or use a flex line, looked at a few ss clad lines. From what I've read, 5/16" ID? I'm going to expose fuel tank and see how things look. Guess is ill need to replace all to fuel pump.

In general I agree with you on filter after pump, in particular with a mechanical fuel pump, which I'm going to stick with for now.

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billspit Bill Kea
Moore, Spartanburg, SC, USA   USA
Why would you not want a filter before the fuel pump?

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
I'm no authority on fuel pumps but I do know a bit about pumps, in particular water pumps. To me, having a filter on the suction side beneficial for the entire system, but not always practical. Depends on whether you have flooded suction or have to pull suction lift, and type of pump. Will be of interest to see what the fuel elevation in the tank is relative to the fuel pump. Assuming the std mechanical lever action fuel pump is a diaphragm style, they usually pull a pretty good suction lift. An inline filter in front of that should be fine, although could lead to more issues such as leaks.

Most electric fuel pumps need flooded suction, have tighter tolerances, designed for higher pressures, filter on inlet side probably necessary.

Still looking around and fishing here for opinions for best overall material to run a new fuel line with. If it's bending metal think ss best in my climate. Never done it, but can make it happen. Have also been looking at option for steel braided flex. I also really like the idea of having a manual fuel shutoff valve somewhere, looked at photo of old style right before the pump?

charleyf Silver Member Charley Fitch
Redding, CA, USA   USA
1962 Triumph TR4
1963 Triumph TR4 "MR.T"
When I said I had a filter after the fuel pump that was to denote that I still had the filter on the pump itself but then a filter near the carbs. I added this after I got some small particles that messed up the float valve.
As to replacing the entire fuel line -- I am restoring a TR3 at present and I have to say that just getting the fuel line in place on a bare frame is a hassle. So consider how you are going to get that new fuel line in place if it does not have a lot of flex.
I have a fuel shutoff just prior to the fuel pump. It is an inline device made for small engines and motorcycles. Very unobtrusive and effective. Very nice to have when cleaning out the filter bowl on the pump. It is sold on Amazon under part number 12121. You would need the 5/16" size of what ever part you use. I have an "original shutoff sitting on the shelf. I would not trust it. It likely needs to be rebuilt as there is a packing inside it. At present I can blow air threw it in the closed position.
Charley

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
Probably replace from tank to junction. Thanks for link on fuel shutoff valve, on the list of things to do. The oem style sediment bowl/filter must not be doing its job if you needed a secondary filter. Hmmm.

Interesting looking around on this subject, one vendor I use often shows an AC brand metal in line fuel filter mounted in the same general area. Might be more to all this.

Going to have some minor welding done on shock mtg plate, bad weld are best. Wonder if anyone has done any extra bracing on these? Sure seems like it needs it.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
The concern I've heard about a filter before the pump is that it reduces the relative pressure in that area; which can aggravate any tendency towards vapor lock. Part of the problem is that the mechanical diaphragm pump doesn't draw steadily but rather takes short bursts every other crankshaft revolution (the length of the burst depends on how much fuel it can move into the carbs during the other half of the cycle).

But not all filters are created equal. A screen type filter would probably be fine, as it presents minimal resistance to flow (assuming it's sized large enough and not clogged). A paper element type filter presents a lot more resistance to flow.

And a paper element filter gets worse if you manage to get some wet gas. Any water will cause the paper to swell and block off the flow of fuel. That has happened to me a couple of times, always during family road trips. When it does, there is a LOT to be said for having the filter under the hood, where you can (if necessary) drive a nail through the element to get enough flow to continue.

My wife's Dodge Caravan had the filter mounted to the frame rail, and it was noticeably harder to change on the side of the road than my 65 Olds was. The Olds died sitting at a train crossing, with a long line of people behind me, and a long line coming the other way. I heard a few choice words as they went around after the arms went up smiling smiley

If your memory is like mine, having a non-standard filter where it can be seen also makes it more likely to get changed on a regular basis.

Like Charley, I noticed some very fine silt that was making it's way through the original sediment bowl and screen, but getting trapped in the bottom of the carb jet assembly. We get a lot of dust in the air around here (especially when the wind is blowing in from the desert) and the dust is very abrasive. Adding a filter seemed like the thing to do; but I put mine up by the carbs and change it every few years as preventative maintenance. (I also run paper element air filters, as the stock mesh does little or nothing to keep that fine sand out of the engine.)

I also found the original (to earlier cars, it was deleted later on) fuel tap fairly easy to rebuild. The original cork shrinks fairly quickly and has to be fiddled with fairly often to stop it leaking. I instead found a length of nitrile fuel line that was the right outside diameter, and cut a length of it to fit. It was tricky getting just the right adjustment on the stem (loose enough to move the tap, tight enough to not leak), but once I did, it worked great. That had to be about 1990, and I think I've tweaked it twice in almost 30 years. (I moved it from the wrecked TR3A to my current TR3.)

The tap is most useful when cleaning the sediment bowl. Otherwise, if you have more than perhaps 1/4 tank or so of fuel, it will run out while the bowl is off.

That's another argument for having the filter up higher; so you can change it with a full tank of fuel.

Just for amusement value, here's a shot of the sediment bowl as it came off of TS39781LO the last time.





Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
I was hoping you would chime in Randall, that all makes sense. Use the factory sediment bowl/filter as a primary and then install a secondary filter right in front of the carbs. Just exposed the fuel tank, it's going to have to come out and at the least sanded and treated, maybe replaced. Are there any drawings out there of the stock fuel tank? Really need to replace the fuel line all the way, hoping I can figure out a safe, practical way with braided flex line. Imagine the issue from what I'm hearing and seeing is going to the the OD vs steel.

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
Who owns the blueprints of the TR's? Would love to have a copy of the fuel tank drawing.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I don't know, never seen such a thing. But don't forget, there are at least 3 different fuel tanks and they don't interchange very well. You'll probably want the late TR3A (post TS60000) one.



Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
My father offered to have his fabricator make a new tank out of 1/4" aluminium, which would be sweet! Need to remove old tank and at least treat exterior oxidation, maybe more. Options so far are to trace the tank out on paper or ship it back home to VA to get duplicated.

templebuchanan Silver Member Temple Buchanan
Crescent City, CA, USA   USA
1961 Triumph TR3A "Buck"
Pulled the old tank and fuel line all the way to fuel pump. Good move, bottom of tank in pretty bad shape, lot of rust in tank especially under sending unit. Tank maybe salvageable but will be looking to replace 1st I think. Outlet holes on both sides, maybe not original tank?

Like to run 1 piece flex fuel line from tank to filter.


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charleyf Silver Member Charley Fitch
Redding, CA, USA   USA
1962 Triumph TR4
1963 Triumph TR4 "MR.T"
Your picture is of an original late tank. One side has the outlet while the other larger bung is a drain plug. As Randall says there are earlier tanks and the outlet location varies. The tank shape is also different.
Charley

andy303 Avatar
andy303 Gold Member Andrew Blackley
Chardon, OH, USA   USA
Macy's Garage has an image illustrating the different shapes, which changed due to the location of the occasional seat and then the move to the flat floor in the post TS60K cars:


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