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TR2/3/3A Electric Fuel Pump Installation

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M

mastaphixa

Jedi Trainee
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I am interested in installing an electric fuel pump and have several questions:
1. Can the electric pump be installed in series with a functioning mechanical pump or does the mechanical pump have to be removed? I would like to install the electric pump and be able to select it on with a switch when desired.
2. How is the output pressure from the pump regulated?
3. What is the best location to mount the electric pump?
4. Recommendations for a pump would be appreciated.

Regards,
Steve Baker
 
1) Yes, but you remove many of the advantages of switching to an electric. The mechanical pump adds heat to the fuel, since it is attached to the engine block. So leaving the mechanical pump in increases your chance of vapor lock. Also, both pumps have pressure regulators. The mechanical is set really low...like 2 psi. Most off the shelf electrics are higher, like 6 psi. You will need to ensure you don't get too much pressure at the carbs.

2) Cheap electric pumps have no pressure adjustment. Good ones do, and will have instructions on how to adjust the pressure. The best pumps give you 14psi at the tank, and then use a regulator immediately before the carb inlets, to ensure sufficient fuel delivery in all conditions with min chance of vapor lock.

3) As near the tank as possible. Pumps push better than they suck. One of the reasons modern cars have their pumps IN the tanks.

4) I've never had luck with any electric pumps. I learned to accept they would fail every couple years and carried an extra when I used them. Perhaps someone else has found a good one...
 
1. Yes, but why would you want to? If the diaphragm fails, it's still going to dump fuel out.

2. Depends on the pump. Some have a relief valve, others regulate the same way the mechanical pump does (the solenoid sucks fuel and a spring pushes it out).

3. Usually, the pump maker advises down low and near the tank. But that's a lot more hassle to install and service.

4. For a simple setup on a stock engine, I like the little rectangular Facet "clicker". In fact, I carry one as a spare for long trips. It only takes a few minutes to install it temporarily (near the stock pump) if necessary.

But oddly enough, the only time I have ever used it that way was on a Stag that had an electric pump as original. The original mechanical pump on my TR3 (and the ones in several previous TR3A) has never let me down during a trip. Even my big American car has been towed twice for a bad electric fuel pump!

If you do convert to electric, be sure to either get a pump with the proper output pressure, or add an external regulator (which is probably the best setup for a high power racing engine). I forget the exact spec offhand, but SU and Weber carbs only want something like 2 psi, while American carbs take 7 psi. Too much pressure can overpower the floats and dump raw fuel into the engine (or on the ground); possibly only under certain conditions. Not enough pressure (or flow rate) can starve the engine at full power, which can lead to other problems like melted pistons.

PS, TRF sells a proper rebuild kit for the original TR2-4A pump. It includes the shaft seal that is missing from most kits, a proper brass screen, and an uprated nitrile rubber seal for the sediment bowl. Also compatible with ethanol in the fuel. Worth the price IMO.
 
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I have always used the mechanical pump but do carry an electric for quick recovery should the mechanical unit fail. It is the work of a moment to insert the electric between the 5/16" line from the tank and the 1/4" line to the carbs. The key is to have the correct size hoses of sufficient length already on each end of the pump.

Electric%20Pump%201_zpshwlaoubb.jpg


Power sources are the coil (white wire terminal) and any ground. That way the pump is switched with the ignition key.

Not really worth it (IMO) to have the pump always mounted as a ready back-up - plus some electric pumps restrict the flow a bit when they are not operating.
 
I have toyed with both. The diaphragm in the mechanical pump in my Tr250 developed a hole in it and while sitting for a few weeks over 4 gallons of gasoline seeped into the engine sump. Yips! Only had 5 psi of oil pressure after several minuets of trying to start. It was recommended to me to go to an electrical pump. Good idea. No worries of fuel getting into the engine. However other problems arrive. You should install a oil pressure switch that shuts the pump off when the engine stalls. Daughter left the key on after the car stalled and walked away for a while and of course a big puddle of gas under the car. After storing the car over the winter the fuel in the float bowels evaporates and when you try to revive it in the spring there is no fuel to get the engine running to build oil pressure to start the pump and fill the carbs.
After a couple of frustrating years of that and a fuel tank liner coming apart and plugging the fuel lines (I thought the e pump was getting week) I purchased one of those new "better" mechanical pumps Moss was selling and installed that. Didn't cure my problem but left it in because it was suppose to be better. Well just this past summer at the TRF Summer Party LaMans start the pump went out. Less then 2 years old. A friend at the race had a nifty kit he put together with a Facet electrical fuel pump (like GEO) with fuel lines already hooked up. All I did was pull the lines off the machenical pump and wire to the coil and ground it and it was able to pull fuel right through the mechanical pump and get me back to TRF and purchased one of their hi end pumps for $99. Holy jeepers Mr. Wilson! I have talked to owners that have had many fuel delivery problems and have mounted an in-line electrical pump with their mechanical pump with a switch under the dash which can be switch on on the fly if need be.
So what I'm doing is staying with the mechanical pump and like Randall, GEO and my friend Don I'm putting a small tool kit together with an electrical pump and all the fixings to make sure I get home.
The pic is the E pump when it was installed in the TR250 with a blanking plate and a bracket screwed to it. Also you can see the oil pressure switch mounted below.
 

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For the reasons you describe, I have a fuel pump relay that senses distributor rotation. As long as dizzy is turning, my facet pump is energized. If fuel evaporates from sitting the pump adds fuel since the distributor is spinning as you're trying to start it. If engine stalls pump stops.
 
There are several extra TRiumph components that I keep in the trunk of each of my TR's. One is a fuel pump and another is a water pump. These do not take all that long to change out and are impossible to find at any local store. In addition are a coil and points.
Charley
 
install electric fuel pump near the fuel tank along with an inline filter. You will also need to install a fuel regulator. the fuel pressure should be set to 3 PSI and be installed just before the carburetors.
 
Or use a pump that generates the right pressure.
 
Hi,

I have a Carter (60504) inline fuel pump mounted on TR-3a. Its rated at 4 psi. Its not the rotary vane style pump they make for V-8's. I had to put a Holly pressure regulator on it to get it down to 2 - 2.5 psi. I have a shock sensor on it incase I get hit / roll the car it shuts the pump off. I had it wired at the ignition switch, but the voltage drops pretty low at the switch. I ended up mounting a secondary fuse panel with relay so the pump has a reliable 13.7 volts. I run a fuel filter going it the pump and a second going into the regulator. The gas tank has been replace. It has been very reliable so far.

If I had to do it over again, the most expensive mechanical pump would be cheaper / easier. :smile: I would still keep multiple fuel filters in the system.

RG
 
Interesting, that's essentially the same setup I have on my Porsche. Works well for me. I have a Facet pump, the one that puts out 6-7 PSI, and Holley regulator taking it down to ~2 PSI. Also the same cutout in case of an accident. I've removed the mechanical pump.

In the on-line 912 group where I am a member, it is common to add an electric pump without removing the mechanical pump. The logic is that the mechanical pump doesn't prime easily after the car has sat unused for a while; then, the driver can flip a switch to reprime the pump, and the car starts easily. I have made to point many times that having both an electric and mechanical pump doesn't seem to make sense, but I'm decidedly in the minority. Oh, well..
 
Well, since it looks like we're gonna run with this dead thread...

If you are going to use a regulator at the carb, Mallory makes a 14psi pump to get the fuel forward on those 1-1/2 G starts. You might as well use plenty of pressure to get the fuel to the regulator.
 
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