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MG TD TF 1500 - Fuel Pump Pressure?

Was wondering if anyone knows what the fuel pump pressure is for the 1952 MGTD. I'm hoping to go to my local parts suppliers and pickup an aftermarket electric fuel pump, like the little cube type and just run it inline. I welcome any suggestions, Thanks, Charlie
ckf Plaidman

It is relatively low pressure; I've heard 3 to 5 pounds per square inch.

Jeff
J Brown 1

Charlie - The standard AUA 25 SU fuel pump used on the TD puts out 1.5 psi. The little, square, run all the time, make a lot of noise, Facet pumps available at NAPA have a low pressure version that has an output pressure specification of 2.5 - 4 psi, which will work fine if mounted back by the fuel tank. See the article, Backup Fuel Pump in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ for part numbers of pumps that will work in this capacity. Cheers - Dave
David DuBois

Charlie, if you cut the fuel line to install an inline pump, and use rubber hoses to make the connections, you will need to add a ground to your fuel level sender as it uses the fuel line for its ground.

warmly,
dave
Dave Braun

hey charlie, why are you interested in installing another pump? regards, tp
tom peterson

Tom, your question is very valid. After all, some of the charm of these cars is their idiosyncrasies and the SU pump is part of this.

Charlie, think of the stories you can recount to a breathless audience, hanging on your every word over the dinner table, about how you had to get out every few miles to tap the pump to make it tick enough to get you home. What heroics!! Take the moment!! (I had sometimes to do a similar thing to the magneto on my Tiger Moth before the engine would start although, thankfully, not whilst in the air). My advice would be to abandon thoughts of electrically assisted pumping and to have experiences such as these, which can be embellished with every glass of Chateau Yuk de Puke.

In England, where I grew up, this happened many times to me in my dad's Morris Ten, Series-M which had the same setup. There it rains eight days out of seven and the memories of having drips run down my neck while tapping, together with a vicious belt off sparking plug leads up my soaking wet raincoat sleeve when a female companion pulled the starter, are memories to be cherished for life.

Roll on MGs.
G.E. Love

Instead of adding a pump, why don't you consider switching to a solid state S.U. pump. I finally gave in and bought one about 3 years ago from Moss and it is totally reliable and even ticks like the origional. Externally, it looks the same.
Steven Tobias

" think of the stories you can recount to a breathless audience"

Do you mean like this:
Consider the following scenario: You are traveling north on I-5 and are just north of the Weed airport using airport transfers tunbridge wells in Northern California (sounds remote, doesn
David DuBois

See? That's what's cool about a TD. You never have to have fuel running down your elbow when you change a fuel pump.
Dave Braun

A later Tf will not only run down your arm, it will also cover your face.
LED DOWNEY

David D:
LMAO....Thanks for the story...and awaking a great memory!
1968 : Friend of mine and I hitch-hiking down the coast spent 3 days trying to get a ride next to the "Weed" sign, (we were "dumped" there after learning you could not hitch-hike in WA or OR)...finally got picked up by 4 females in a Metro Bus painted with flowers and went all the way to Big Sur with them. I think we had more fun and a fonder memory of "Weed" than you do!
Cheers,
David 55TF 1500 #7427
David Sheward

After having a similar "on the road fuel pump failure", I added an auxiliary low pressure electric pump from Auto Zone. It cost me about 14 bucks as I remember and I mounted it on my TDs frame back where it arches up and over the rear axle. I installed a three position switch on the steering column bracket that has a forward (original pump), a center (off) and rear position(rear aux pump)to select which pump to activate. I have switched between pumps on the road many times and noticed no difference in engine performance. No more roadside fuel pump maintenantce since then.
Jim Merz

If you are after a good quality quiet pump, and not the cheapest, the NAPA #477060E is a good choice. I am not sure who actually builds this pump- it shows up as a Purolator, NAPA, and maybe Bendix?

http://facet-purolator.com:80/index.php?option=com_content&task=category§ionid=7&id=14&Itemid=36

Another good option is the Autozone Airtex pump- E8016S

http://www.autozone.com/Ntt,E8016S/shopping/allResults.htm

These are both centrifugal pumps and run quiet. The reported failure rate is much less than the square facet pumps.

FWIW
Dallas
D C Congleton

Hey Dave (Dubois), I agree that no man-made product is perfect, however, I feel that certain old systems, when brought up to modern reliablity standards, can be relied on to be less likely to fail. Where does one draw the line? There are so many components in our cars that were reputed to be less than perfect through the years. Add more than a half century of use and exposure to less than perfect conditions to the mix and you have a recipe for total lack of confidence! I have to say that I have been somewhat blessed; in my many years of driving old British cars, I have not had any reason to develope a mistrust of all things Lucus and SU! For instance, my discarded old fuel pump (the only one that failed me in 3 cars in over 90k miles) was probably as old as the car. I think that when I reassembled it after a rusty fuel tank clogged it, I buggered the re- installation of the diaphram. I messed with it constantly, trying to assemble it with the plunger activated as the book says. I think that the tension was never correct and when it got hot it seemed to labour and overheat. Interestingly, the old mechanical points were never an issue. I felt that it was worth the price to get a modern version, built with modern materials and technology, tested in the factory.
All of my ignition and the balance of my fuel system components have been in the car (failure free, even during periods of high humidity) for over ten years, INCLUDING the ignition points.
Steven Tobias

Steve - I think that the key phrase in your post is "less likely to fail". That is the neat thing about any electromechanical device - you never know when it might fail. Yes, the all electronic SU pump I have in our MGB has not given us a bit of concern in over 6 or 7 years and neither has the SU pump in our TD that I modified with my optical trigger at about the same time. On the other hand, I have had a few of the all electronic pumps come to me for repair because the quit working in the first few months of service. I have also had a few of my modified pumps come back because they quit working.

I agree with you, that the Lucas and SU products are all very reliable (I get a bit tired of all the Lucas jokes after awhile - the only electrical component I have had a problem with over the years I have been driving, was a Bosh product). The majority of pumps that I receive for restoration and modification have died from old age or abuse (a clogged line from the tank to the pump will do in a pump in short order if the ignition is left on continuously while troubleshooting). The other really big problem that I see is owner repairs. The first thing that most people do when their SU pump fails is try to fix it - it is after all a pretty simple device and the gives instructions to do the repair, so let's just fix it and save some money (that was my reaction the first time I encountered a failed SU pump on our TD). What I (and a majority of people) found out, they are really not all that straight forward to make work properly or long term. Over the years, I learned their idiosyncrasies and how to deal with them. I also made up a test stand so I could check that my fix was in fact going to work (I run the pumps in a simulated working environment for 24 hours before I send the out). The result of this is that I often get a pump in pieces or read on one of the forms that "all SU pumps are a piece of crap and should be replaced with _____ (fill in the blank)pump. It leaves me wondering how many people would feel the same about, say the XPAG engines if they were so quick to jump into them with no training, tearing them apart and trying their hand at rebuilding, using on the shop manual as a reference.

The other thing that I have noted over the years - in all of the newsletters, bulletin boards and forums, one of the most common items written about are fuel pump problems and how to deal with them. I have seen everything from beating them with a rock to using a blood pressure pump to pressurize the fuel tank to get home with the car (beating them with a rock is not valid, the blood pressure pump is). That coupled with my personal experience, lead me to a permanently installed backup pump that can be switched in if the primary pump fails. I still feel that this is a reasonable approach to a problem that so often occurs on the road. This problem has become more frequent as people drive their MGs only occasionally, letting them sit undriven for long periods of time, allowing the points to film over. When this film build up sufficiently, it will cause the points to quit conducting current. This will often happen after the car has started initially and the wiping action of the points push the film into a (relatively) large pile. This is where the all electronic pumps or my optical trigger helps, in that there are no points to film over. These modifications (the all electronic circuit card can be purchased from Burlen Fuel Systems and installed in any SU pump) eliminate the problems associated with the points, but do nothing for old stiff diaphragms or pumps that have been gummed up with old stale fuel left in them, so there will always be problems associated with the fuel pumps (even the little, square, run all the time, make a lot of noise Facet pumps - I had one of those fail on our pickup truck) - it's just a matter how ofter and/or when. Cheers - Dave
David DuBois

Before switching to an aftermarket fuel pump you may want to read about my experience with an MGB. I think that the a solid state fuel pump is a very good way to go, but just be careful.


Leaking Carbs

I thought that I would share with the club the solution that I found for fuel leaking from the rear SU carburetor's overflow vent.

I had an intermittent, but substantial leak, from only the rear SU HS4 carburetor on my 1964 MGB engine. I lost approx. 1-pint of gasoline every 10 miles that, in turn, resulted in a fuel consumption rate of about 15 MPG (US). Additionally, the engine flooded and sputtered when the leak was at its maximum. I was able to monitor the fuel leak by capturing the lost fuel by using a Mayonnaise jar with a hole in the center of the lid through which I inserted a tight fitting 1/4 inch plastic tube the other end of which was connected to the rear carb overflow vent. I also vented the jar with a small 1/16 inch hole near the center hole.

As a point of information, the fuel pump I was using was an aftermarket Airtex with an output pressure of 4.5 PSI. The pump is located under the car and mounted on the frame close to the rear axle.

I tried the following in an effort to solve the problem.

1. Checked to see if the float adjustment level was correct, the needle valves seated and sealed and that the floats had no leaks.
2. Replaced the standard float needle valves with Grose jet assemblies. …No help!
3. Switched the Grose jets from the front to the rear carb. …No change, the rear carb still leaked!
4. Replaced the rear float bowl cover, Grose jet and float with known good units. …Rear carb still leaked!

After trying the above, I decided that the problem must be too much fuel pressure from the Airtex fuel pump because the SU pump puts out only 2.5-PSI. I searched the Internet for the lowest output pump that I could find. This turned out to be a Mr. Gasket 3.5-PSI pump. I thought, for sure, that there would be at least a 1-PSI tolerance in the Grose jet assemblies. I purchased a new pump on E-bay for $25.00 and installed it, in line, with the Airtex pump.Using an "on-off-on" switch I am able to use either pump, with the Airtex being the backup. To my surprise, the leak was still there.

My next attempt was to install a fuel pressure regulator. I found a Mr. Gasket fuel pressure regulator with an adjustment range of 1-PSI to 6-PSI. on Amazon.com for about $30.00. I installed it on the underside of the car between the Mr. Gasket fuel pump and the carbs. To my surprise the pressure regulator reduced the pressure too much even at the 6-PSI setting, and starved the carbs of sufficient fuel to enable the engine to run. Now I was really perplexed. As a last resort, I removed the regulator from the under side of the car and reinstalled it in the engine compartment. Low and behold at a setting of 3.0-PSI the fuel leak is gone and the engine runs great. Problem solved!!!

A suggestion… If you are experiencing high fuel consumption, a smell of gasoline while driving or see an occasional puddle of gasoline on the pavement below the carbs, you may be experiencing the same problem that I had. Try the Mayonnaise jar idea described above to see if you do have a carb leak.

E-mail me or call If you have any questions. 843-838-0822


Frank Grimaldi

Any Member,
If someone can shed some light on an electrical problem with my MG, I'd appreciate it. 1953 MGTD / frame off restoration / new bumblebee harness/ generator and regulator bench tested o.k. @13.5V, 800 cc new battery / positive ground car. CAR STARTS ON A DIME AND RUNS LIKE A CLOCK. HOWEVER ....
1. when the car is idling and I disconnect battery with battery cut off switch, the car STOPS
2. both green (gas) and red (ignition) lights stay on when ignition key turned or car running
3. new battery is DRAINED within days. Then battery needs a charger. (Car will start with a jump)
4. A voltmeter cannot be within 3 feet of engine bay due to "secondary inteference" causing readings to be all over the map.
5. Ammeter in car always flicking slightly negative from zero when car running and increases negatively somewhat when head lights are turned on
ANY IDEAS???
Thank you. Larry Hudson
email: lhhudson@rogers.com
L.W. HUDSON

Possibly you are running off battery power only, and eventually draining the battery, because the generator is not polarized. I'd re-polarize the generator (see archives - takes 2 seconds) and go from there.

Cheers

Larry
L Karpman

Is anyone running a standard 1250 XPAG with one of the SU competition double ended fuel pumps as a main pump and backup pump? I ask because it seems like it would be the simplest fix - no extra fuel lines or valves and easier wiring and switching... and Moss claims it does not require a pressure regulator ...

pricey though...
Geoff Baker

Larry - " A voltmeter cannot be within 3 feet of engine bay due to "secondary inteference" causing readings to be all over the map."

First off, leave the digital multimeter on the bench where it belongs, go to Radio Shack and get a mid level (perhaps the only) analog meter to use with your car. The non resistor wires and plugs to your spark plugs are producing enough radio interference to cause your digital multimeter to go crazy (you ought to see the in a transmitter site for a radio station).

Second, go through the wiring in your car. You may have to resort to disconnecting each end of all the wires and starting over again, but that may be the only way to trace down the problem (remember, wires that are connected in an automobile have all sorts of sneak paths that an lead you astray when either end is hooked up). As you trace each wire and determine where it belongs, leave the ends disconnected and mark where they need to hook to. Once you get all the wire ends identified, then you can start hooking them up. Once hooked up and ready to apply power to the system, attach the ground cable to the battery through a 10 amp fuse initially (that way, if there is a screw up in any of the primary power connections, the fuse will blow rather than a wire going into the incandescent and incinerating your wire harness.

Once you get all the wiring straightened out, then polarize the generator (if you are uncertain of how to do this, see the article, Polarity Change in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/) to insure that the generator is putting out the proper polarity voltage. After doing that, check that the generator and the regulator are, in fact putting out the correct voltage by following the instructions in the article, Testing a Dynamo/Generator in the above section of my web site (I know, you said that the generator and regulator had been bench tested, but the test should be rerun with the two components in the car and hooked up to work as they are intended. Finally, if all the above tests are satisfactory, connect the multimeter across the battery, write down the voltage, then start the car and rev the engine and see if the voltage is going up as it should (the 13.5 volts obtained on the bench test is a bit on the low side, it should run the battery voltage up to around 14.5 volts - Bob J., Correct me if I am wrong about this). Cheers - Dave
David DuBois

Can't resist telling this one again...

Austin Mini...3 oclock in the morning...NY state thruway heading north to the Blue Water Bridge...on the way to a boat race... racing boat on top of the Mini on a rack...racing engine in back seat....
fuel pump quits
pull out extra 4' of fuel line from trunk...have mechanic friend (who was asleep a few minutes before) hold my racing engine in his lap...run extra fuel line out the window and under hood (now open on safety latch) and plugged into carb....bolt stuck in end of fuel line in case the pump starts)
The tank holds two quarts...the fuel line is clear...we watch the final bubble go down across the hood, then pull over and fill with racing av-gas...then continue on our way.
Stopped 53 times on the way home......whew...tired just remembering it....

gblawson

The first owner of my TF fitted a 'puller' SU pump on the toolbox like the TD's and early TF's. This is in line with the existing pusher pump and connected to a switch on the dash. Anytime the original pump starts to fail (very rarely) I just flick the switch and keep driving.

Cheers,
Matthew.
Matthew Magilton

Geoff - "Is anyone running a standard 1250 XPAG with one of the SU competition double ended fuel pumps as a main pump and backup pump? I ask because it seems like it would be the simplest fix - no extra fuel lines or valves and easier wiring and switching... and Moss claims it does not require a pressure regulator ...

pricey though..."

VERY pricy and not really suitable for a TD, unless it is mounted under the car in the back, by the fuel tank. A member in our local 'T' register was sucked into buying one of those double ended pumps for his TF. When he got it home, it hit him that this was not a suitable pump for his car and it is still sitting on the shelf. Yes, the AZX 1400 seres pump can have each end run alone, with a switch to swap ends if one end fails, but it is a high price to pay for redundancy when one can go down to NAPA and get a little, square, run all the time, make a lot of noise Facet pump for about $40 to stick in line with the stock SU pump and a switch to switch power from one pump to the other and accomplish the same thing - see the article, Backup Fuel Pump in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Also no extra fuel lines or valves and the wiring and switching is just as easy to do and the Facet can be had with on output pressure that is much closer to the stock SU pump for the TD instead of 2 to 3 times the pressure that is produced by the double ended pumps. Cheers - Dave

Just for the record, the AZX 1400, AZX 1500 and other double ended SU fuel pumps were not produced for competition, they are OEM pumps on many of the larger vehicles, such as Bentleys, Rolls Royces and such. they were meant for cars with engines that are essentially gas guzzlers. Cheers - Dave
David DuBois

Thanks Dave D,

I sort of suspected that it might not be appropriate. Because of the design you need to fabricate a different bracket and place it differently than the standard pump, plus as far as I could see it's not even an electronic version, just a double ended standard SU pump. As you say, designed for bigger gas guzzlers, not as a backup system. Too bad, seems like with a little work someone could build a two-in-one system that was reliable and easy to install... and cheaper too.

Back to the drawing board.
Geoff Baker

Geoff - "...as far as I could see it's not even an electronic version, just a double ended standard SU pump."

Like all of the SU pumps availble today, the double ended pumps are available in the all electronic version.

"Because of the design you need to fabricate a different bracket and place it differently than the standard pump...

Yes, it requires two brackets similar to the ones used on the early MGBs and room to mount them.

"Too bad, seems like with a little work someone could build a two-in-one system that was reliable and easy to install... and cheaper too."

That would be the little Facet pump and my installation (it can even be mounted in the engine compartment). One gentleman in Australia just wrapped his in foam rubber and tucked it into a part of the fender well in the engine compartment of his MGB. Cheers - Dave
David DuBois

Dave, had you been driving a "proper" car, then you wouldn't have needed a jack to replace the fuel pump. ;)
Steve Simmons

Steve - You are right. Still, I would have been on the side of I5 with traffic streaming past at 70 plus and the cold wind blowing on me, trying to turn me into an icicle. Maybe I am getting lazy in my old age, but I opt to not have to replace anything on the car at the side of the road (you haven't lived until you have had to change a tire that was destroyed by a rock on the side of the road in the Lakes District in England - there wasn't even a shoulder to pull onto). Cheers - Dave
David DuBois

This thread was discussed between 23/02/2009 and 11/12/2009

MG TD TF 1500 index

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