View Full Version : Electric Fuel Pump or carry a spare Mechanical?

02-06-2010, 02:06 PM
I was having a weird sputtering at higher RPM, like my engine was fuel starved. I guess the old electric was close to death or just wasn't up to snuff for 3rd gear down-shift passes on the highway :smile:

I have a mechanical fuel pump hooked up now, and my Spit is running a lot better. So my question is, should I get a new electric fuel pump or carry a spare mechanical?

If I get a new electrical, what specs should be on it to make sure I always have adequate fuel delivery? I have 1 carb, for now, and plan on getting a TC setup going shortly. I suppose I could just get a powerful one and a Fuel Pressure Regulator... but I wouldn't know what pressure to set the regulator to. I'm sure it can't be very much to push around my oh-so-powerful 57bhp :yesnod: Thats right! FIFTY SEVEN TO THE WHEELS!

Andrew Mace
02-06-2010, 02:11 PM
Typical small Triumph carburetor requirement are around 2.5 psi -- fairly low! I think it's a toss-up as to which pump could be put into service more quickly in an emergency.

02-06-2010, 04:32 PM
I run the stock mechanical pump, and carry a small Facet-type electric as a spare. Probably it's easier on a Spit, but on a TR3 changing the stock pump is a lot more difficult (and takes special tools) than temporarily connecting the electric. Plus it's useful for other things, like transferring fuel around. It's also a lot less likely to get damaged, stored in the center of the spare tire. Come to think of it, I'm not sure the mechanical pump would even fit in there!


02-07-2010, 08:42 PM
I have installed a Carter's Pump in my TR6 and TR3A. No problem anymore...Or at least you work on something else.

They have a model that delivers a max of 3 PSI. That's the one to have. No regulator needed.

02-08-2010, 09:01 AM
I have both in my 1969 TR6.
My car operates with a very fine rebuilt mechanical pump.
I have a hard wired Facet electric with fuel lines already
installed. About a 5 minute procedure to switch over to the
Facet. I also carry a spare mechanical pump in the trunk-
"just in cast" . I think my mechanical puts out 2.3 psi
and the Facet puts out 3.0 psi. If I remember correctly.

hope this helps.


02-08-2010, 06:30 PM
Is that 3psi Facet going to be good enough for twin carbs later?

02-08-2010, 09:15 PM
Sure, you don't need more pressure for more carbs. And ISTR Tinster already has the stock twin carbs.

02-09-2010, 08:08 AM
Yup. It'll feed a pair of HS6 SU's or two 40-DCOE Webers just fine.

02-09-2010, 09:35 AM
Hey all
can you install both electric and mechanical and simply pump thru the mechanical. Basically a redundant setup

02-09-2010, 10:03 AM
How about the opposite situation: will fuel pass through an electric pump when its not pumping? There's a spot in the fuel line between the tank and the mechanical pump that I think would be a good spot to hide an electric backup pump, but I would not want it to restrict flow.

02-09-2010, 11:35 AM
Fuel will pass through the Facet pump. I have on mounted bank close the tank on the spare tire cover on my TR3.


02-09-2010, 01:08 PM
Yup. It'll feed a pair of HS6 SU's or two 40-DCOE Webers just fine.

PERFECT! Twin Webers is the plan! Thanks Doc!

02-09-2010, 01:14 PM
Fuel will pass through the Facet pump. I have on mounted bank close the tank on the spare tire cover on my TR3.


<span style="color: #990000">I don't know guys but it sounds like a not very good setup. I don't know much about such things but I think the Facets push more than they suck. They're good for 12" of lift?

If your mechanical dies and you switch on the in-line Facet, won't you be pushing gasoline into the broken down mechanical pump? And then hoping it goes thru to the carbs? If you have a torn diaphram, the Facet will be pushing gasoline
into your crankcase as well as your carbs. I'd have to see this set-up function with a broken mechanical pump installed.

I installed my Facet, hard wired with on/off button, and
spare fuel hose pieces to bypass the mechanical and stub it off. I've used my set-up several times and it works quite well.



02-09-2010, 01:29 PM
Guys- is there a weakness in the existing mechanical pump ?
I've used facets on some of my race cars. They're not the best unless
you use the rubber dampening mounts. I use mechanical on the ff car;
much more dependable. It's the KISS principle.

02-09-2010, 01:56 PM
Guys- is there a weakness in the existing mechanical pump ?
Not really, no. But its old technology, old parts, and older stuff is more prone to failure.

02-09-2010, 02:42 PM
I've no experience with the Spit pump, but presumably it's similar to the TR3, which IMO is dead reliable as long as you (a) have an original pump, not an aftermarket imitation, and (b) rebuild it with a new diaphragm.

The original diaphragms would not stand up to the ethanol found in most automotive gasoline in the US today. Old electric pumps had the same problem, I had an early 70s vintage AC pump where the diaphragm turned to silly putty.

Another thing to watch for on the TR (tho probably not applicable to the Spit), the original outlet fitting was a special 'adapter' nut used to fit 1/4" od fuel line into a fitting designed for 5/16" od line. The original compression ferrule was larger than the replacements made today, so if the ferrule has been changed, the nut may bottom in the threads before clamping the ferrule hard enough to prevent leaks. One solution is to carefully file away the last half thread or so; since my nut was already rounded off, I made a new one on the lathe.

Other than that, I've covered literally hundreds of thousands of miles with the original mechanical pump and it just keeps working. I do keep a Facet for a spare (in the middle of the spare tire), but as yet I've only used it for other purposes (like loaning some fuel to a fellow driver; and emptying a fuel tank that needed to be removed). And with some zip ties and clip leads, it only takes a minute to press it into service (which I have done when the original electric pump failed on a Stag).