Electric Fuel Pump vs. Mechanical Pump

[spineguru]

Based on some sound advice on this forum, I am considering an electric fuel pump (at least temporarily) as a means to bypass my mechanical pump, which appears to be on the fritz. I am assuming that the mechanical pump just stays in place, but I have a few questions....

1) If I want to install an electric pump and rebuild the mecahnical pump, is there a cover or something that is made to cover up the hole where the mechanical pump attaches, so I can drive the car using the electric pump while I rebuild the mechanical pump?

2) Do I need to add an inline filter BEFORE the electic pump? Since the mechanical pump has that glass bowl with a mesh filter, it seems that an inline filter would be needed. I, of course have a filter between the mecahnical pump and the carbs that I would leave in place.

3) When wiring the electric pump, should I also attach a safety switch that kills the pump when the oil pressure drops? It seems that without it, the pump will be running when the switch is in the on position, even if the engine is not running.

4) Any suggestions on where to mount the electric pump in a TR3?

5) Lastly, any other tricks to converting to the electric pump?

Thanks.

 

[Terry_Geiger]

A blanking cover from a big block chevy V8 will work. Most auto stores carry a chrome cover that can be used.

A safety interia switch would be an excellent idea. If the car is involved in a collision, the interia switch cuts power to the pump. This is the method used on most modern cars. I don't think I'd go the oil pressure switch route. To me, it is an advantage to be able to turn on the ignition and let the fuel bowls prime before actually engaging the starter. If you car sits for long periods of time the fuel bowls can become dry and it is a nice feature to simply turn on the ignition switch and count to ten, knowing your fuel bowls will be full before you engage the starter.

Mount the pump near the tank and at a level where it gravity will feed the inlet of the pump. I do have a filter installed at the inlet of the pump and then another small filter just before the carbs. I mounted the fuel pump and filter in the boot in the left front corner of the wheel well (same place as the fuel pump was mounted on Petrol Injected cars). I'm not sure what your options would be on the TR3 since the boot is quite a bit different.

Also, one big advantage to an electric pump over mechanical. Mechanical pumps can flood the crankcase with fuel when they fail. This thins the oil and and can cause low oil pressure and eventual engine damage. The electric pump is not connected to the crankcase, therefore there is no chance of this happening.

 

[DNK]

Terry- would like to see a pic of your fuel pump set up location. One of the last concerns in my build.

 

[bobh]

The carbs take a fairly low fuel pressure. You should confirm the correct pressure and either match the electric pump or install an inline pressure regulater.
BOBH

 

[DNK]

Something like this

 

[Twosheds]

I am assuming that the mechanical pump just stays in place, but I have a few questions....

I read somewhere that, if you are replacing the machanical pump with an electric pump, you should remove the mechanical pump. This is for a permanent replacement, not for a temporary swap for troubleshooting puposes, though.

 

[DNK]

Hey DR. John. Where in the fine state of "Drive Gently" do you reside?

 

[Alan_Myers]

Hi,

On my TR4, a Facet electric fuel pump is now mounted on the inboard face of the LH rear shock bracket. It's a pretty convenient location and tucked up enough to help protect the pump from any flying debris. (There are some photos at the link below.)

This is also a useful site because it was easy to mount a Fram fuel filter above it, between the fuel tank and the pump. Be a little careful to keep any hoses clear of the axle's full range of movement.

And be sure the elec. pump is mounted below the bottom of the fuel tank. If mounted any higher, it might occasionally pull air, which can cause it to overheat and burn itself out.

For a street car an inertia switch isn't a bad idea. For a race car, I'd think an oil pressure switch makes more sense (an inertia switch might trip during hard driving). A hidden, manual switch might also be used to help prevent car theft!

I made a simple blanking plate for the old mech. pump location, and just used a standard paper gasket to seal it. If I recall correctly, I made the plate from a small piece of 3/16" aluminum. I am considering using the pump blanking plate to install a nice big crankcase vent and then completely blanking off the breather tube opening that's slightly lower and further toward the rear (TR4A have this blanked off, and the plug used will work on any TRactor 4. cyl. motor).

Yes, you will almost certainly need a fuel pressure regulator. About the lowest pressure pump avail. is 4 psi, and SUs/ZS nees about 2.5 psi, Webers shouldn't have more than about 3.5 psi. On my car, a Holley regulator is mounted in the engine compartment, not too far from the carbs. There are pumps with adjustable pressure. I used a Weiand brand in the past that was easily adjusted. It was quite noisy, though, making a loud TICK every time it pressurized. Easy to confirm it was working, but got a bit bothersome.

Ideally, I'd like to have a pair of Facets. The smallest models are very compact and can be fitted many places. Having two gives some redundancy, in case one fails for some reason.

Along a similar train of thought, some SU elec. pumps are "double enders" with dual pumps, in case one side fails. These were often used as an upgrade in rally and endurance cars. I think some Jags were fitted with them right from the factory.

I suppose an SU pump would be "proper" on just about any LBC. The older ones had something like a set of points to actuate the pump, which required frequent servicing. Newer ones are solid state, making them more reliable and requireing practically no service, but otherwise looking nearly identical.

Perhaps the biggest downside to the SU pumps is that they are pricey, some over $200-300. Facets are pretty cheap by comparision, maybe $50-75 (and a lot smaller).

Use some sort of isolation mounting under any elec. fuel pump. They can be a bit easily upset by vibration. I know Facet sells an isolation kit, which is three or four rubber mounts and a grounding wire.

If you are still running an original style generator on your car, you will need to watch the amperage of any pump you choose. Most aren't particular heavy power users, but the original generator is only good for 17-22 amps at speed, and very much less at idle or low rpm. This is especially a concern if you have any other elec. accessories drawing significant power (an elec. cooling fan, halogen headlights or added fog lamps, etc.) If you have already converted to an alternator putting out 45 or more amps, you'll most likely not have any problems.

One last thing, on the elec. pump circuit for my car, I 've opted to install a self-resetting circuit breaker instead of a fuse. This way just switching the ignition off and back on will reset the breaker if it blows, and I don't have to worry about replacing a fuse. Not that I expect a problem, but who knows! I am using a similar breaker instead of a fuse on the elec. cooling fan circuit.

 

[Jim Lee]

1) If I want to install an electric pump and rebuild the mecahnical pump, is there a cover or something that is made to cover up the hole where the mechanical pump attaches, so I can drive the car using the electric pump while I rebuild the mechanical pump?
======================================================
It would be easy to cover but I just removed the innards of
my pump, essentially the pump lever, and left it on there with a gasket sealing it at the engine.


2) Do I need to add an inline filter BEFORE the electic pump? Since the mechanical pump has that glass bowl with a mesh filter, it seems that an inline filter would be needed. I, of course have a filter between the mecahnical pump and the carbs that I would leave in place.
======================================================
I would definitely put one there.

3) When wiring the electric pump, should I also attach a safety switch that kills the pump when the oil pressure drops? It seems that without it, the pump will be running when the switch is in the on position, even if the engine is not running.
====================================================
I did not. The pump whirs away before I push the starter button which is fine with me unless for some reason I need to test some electrical thing without the engine running.
If it gets too annoying I will disconnect it.

4) Any suggestions on where to mount the electric pump in a TR3?
=======================================================
I actually used a couple of tiny c clamps on top of the beam that is closest to the left hand fender. Its worked fine for few years now and if I ever have to remove the pump it will be easy. The reason I have it up front is that I do not want to have to run wire all the way from the back. If you disconnect the fuel line at the old pump gravity will give you plenty of fuel....be prepared with a small piece of hose of the right size with a bolt sealing it. Also, and I don't know if this is true or not, I was told that these tiny pumps are made more for 'pulling' than for 'pushing' which is what it would be doing in near the tank. The pump is the lowest point in the fuel system but I would be surprised if it did not work at any height. My main concern
was keeping it away from the engine heat which it is well away from.

5) Lastly, any other tricks to converting to the electric pump?
=========================================================
I don't have the wiring diagram in front of me but I just hooked the hot wire into the fuse box where at a connection that is only on with the ignition. Ground wire goes to one of the horn bolts on the left side.

Take care,
Jim Lee

 

[Got_All_4]

These pumps tend to push better then they pull so that's why they should be mounted as close to the tank as possible. I'm not so sure that installing it near the tank is a necessity on a Triumph TR3. I just did my TR250 and mounted it on the plate I made to cover the hole in the block. When I pulled the line out of the filter that went into the mechanical pump there was plenty of fuel pressure just from the gravity flow. The tank on a TR3 is higher then fuel pump and the outlet is at the bottom of the tank resulting in positive fuel pressure no matter where you mount the pump. The pump I purchases was at Car Quest and came with a pre-filter attached. The local Triumph tech told me to use this pump because it has virtually has no noise and a maximum of 4 lb of pressure.

 

[Jim Lee]

Do you have a part number for that pump at Carquest?
Mine makes noise and I'd like to have a spare.

Thanks very much,
Jim Lee

 

[Twosheds]

Hey DR. John. Where in the fine state of "Drive Gently" do you reside?

Is Maryland the state of "Drive Gently"? If so, the HSTRL Soggy Bottom Facility is located near Myersville, west of Frederick off I-70. The Facility is located next to Catoctin Creek. I think Catoctin must be Native American for "Creek that Floods".

I am known locally as "The Guy with All Them Dopey Little Cars".

DNK, I forgot to say that tours of the Soggy Bottom Facility are welcome and may be arranged in advance. However, due to the extreme poverty of the Chief Boffin, the number of Experimental Vehicles has been reduced drastically. Only the Test Mule and Station Hack, affectionately referred to by the staff as The Blue TR3 is currently on hand. The very first TVR Vixen can be seen in the Soggy Bottom Annex, however. Also Dale, the RED '88 Chevy K-1500 Tow Vehicle.

If you decide to tour HSTRL Soggy Bottom, be advised that the facilities are... well... primitive. In other words, be prepared to pee outside.

Love to have you or anyone, for that matter.

 

[Deleted member 451]

When I first got my TR3 I was having fuel starvation problems that I thought was the fuel pump. I went to the parts store and bought the cheapest 4PSI pump they had and a fuel filter. I think both of them came to about $15. Not being a member of this forum at the time, I didn't know that you should mount them near the tank so I mounted it to the lifting plate on the front of the engine next to the dizzy. Five years later it still sits there and works perfectly. I have a new mechinacal pump sitting in a box that I keep telling myself I'll put on when I have other work that I need to do in the area. I drive the car almost every day so I'm going with the old saying about if it works don't fix it.

 

[DNK]

John, The "Drive Gently " Was on the sign in to Va. from the Cabin John Bridge back in the 70's and before. Still to this day that is how I send off visitors at my little castle.
18 years in the metro area. Derwood, Gaithersburg and Potomac. Wife grew up in Aspen Hill area. Mom and big sis live in Poolesville and M.I.L. lives in Fredrick.Will be doing my annual pilgrimage to see my mom the middle of Feb.Maybe look you up with my Bro in law,74 TR 6 and Mercedes parts manager.
Don Kelly

 

[Joe_Pinehill]

Not an expert here, but there are many triumphs on the road with mechanical fuel pumps. If you think you need a pump for extra pressure doesnt that mean there is another problem?

 

[YankeeTR]

I use a small, generic pump that's available from NAPA on my traditional hot rod projects. (it's one of those little square-looking jobs) The old Stromberg 81/48/97 carbs that I use only like about 1.5 lbs. of pressure.

Two different ones are available...I use the low-pressure version of this pump without a regulator and have never had a problem.

I also use these pumps on other applications...my Buick V-8-powered '49 F-1 had one pumping fuel to a 600 Edelbrock and it worked just fine four several years.

 

[DNK]

The stock pump is more than adequate for a stock car. Unless you have modified your 6 it is unnecessary to change it.

 

[Got_All_4]

Car Quest # E8016S. If I recall it was $46. What made me make the change is I took over 4 1/2 gallons of gas and oil mix from the crank case of my TR250. If I ever chance to a alternator I'll do my TR3 too. Trying to get a pic in here. If you want one contact me.

 

[Guest]

The stock pump is more than adequate for a stock car. Unless you have modified your 6 it is unnecessary to change it.

I agree. My engine runs 3 carbs and the stock pump works fine for me.