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MG TD TF 1500 Loss of power BBS discussion at MG-Cars.net
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MG TD TF 1500 - Loss of power
| Hello,
I'll start from the beginning. Filled the tank up last November before putting my TF away for the winter. Did not get to drive it much this year. A month ago, put 34 miles on it, then two weeks ago five miles when the fuel pump died. Empty the fuel tank put a new fuel pump on it started it up ran beautifully. Car held 60 miles per hour without any issues at all. Started going up a hill that was about a mile long, started to hesitate, buck and lose power. Hit Level ground again, car took right off and ran beautifully. Then I took a back road, ran fine until I hit another hill. Then the same thing, loss of power and hesitation. A friend suggested checking the filter on the pump. Before I empty the gas tank again, any other suggestions? Same tank of gas from last year, possible that it's just crappy gas? Thank you for any help you can provide. Todd |
| TR Hammond |
| Before emptying the tank there is a simple fuel delivery test you can do.
Disconnect the fuel hose from the front carburetor and direct it into a jar. Have an assistant turn on the ignition, look for a strong pulsing stream of fuel. If it is good you could perform a timed delivery test to verify exact output ,but I would not bother. By doing this you have checked the 2 filters, the one in the tank and the one in the pump and not a drop of fuel is wasted. When you next empty the tank, contact Tom Lange at www.mgtrepair.net and get a tank drain kit that will allow you to easily drain the tank in future. If you have good fuel delivery it is unlikely to be crud in the carburetors, but worth removing the bowl lid and floats to check the bottom of the bowls. Peter |
| P G Gilvarry |
| Did you add sta-bil to the tank of gas prior to storage? What is the pump out put at the carb? If normal, can you raise the front end of the car or stop on a grade the same as you were driving, pull the fuel hose from carb, place the end in a fuel can and check the pump output? Regards, Tom |
| tm peterson |
| I would be looking at dirty strainers at the tank, Pump and carbs. Remove the bowl lids and floats and look for debris in the bottom of the float chambers. Swab them out. Remove the dashpots and gently blow air pressure back through the jet to dislodge debris, swab out the float chambers again and reassemble. If the tank has not been sealed I can say with certainty that rust is floating around in the tank. When the car is driven this rust and other debris from years of neglect gets agitated while driving and clings to the tank strainer restricting flow to the pump. This is particularly true when the engine is under load requiring more fuel consumption. When the engine is shut off the larger chunks fall freely back into the bottom of the tank. If after doing all of the above and then finding more debris in the float bowls after a short period of driving time it is likely time to remove the tank flush it out, clean the tank and seal it. Modern fuels containing ethanol will promote corrosion of steel tanks and does go bad in a short period of time. I would dump the old gas and use it in your lawn mower. The ethanol is hydrophilic and draws in moisture.
Both LaVerne Downey and myself have separate threads detailing instructions on sealing tanks in the archives. Once you’ve determined it’s not a fuel delivery issue the next item will be related to ignition. Bill Chasser TD-4834 |
| W A Chasser |
| I would be looking at dirty strainers at the tank, Pump and carbs. Remove the bowl lids and floats and look for debris in the bottom of the float chambers. Swab them out. Remove the dashpots and gently blow air pressure back through the jet to dislodge debris, swab out the float chambers again and reassemble. If the tank has not been sealed I can say with certainty that rust is floating around in the tank. When the car is driven this rust and other debris from years of neglect gets agitated while driving and clings to the tank strainer restricting flow to the pump. This is particularly true when the engine is under load requiring more fuel consumption. When the engine is shut off the larger chunks fall freely back into the bottom of the tank. If after doing all of the above and then finding more debris in the float bowls after a short period of driving time it is likely time to remove the tank flush it out, clean the tank and seal it. Modern fuels containing ethanol will promote corrosion of steel tanks and does go bad in a short period of time. I would dump the old gas and use it in your lawn mower. The ethanol is hydrophilic and draws in moisture.
Both LaVerne Downey and myself have separate threads detailing instructions on sealing tanks in the archives. Bill Chasser TD-4834 |
| W A Chasser |
| I am not going to disagree with Bill's for one minute, however on a TF to physically check the tank and pump strainers you need to drain the tank. With only a drain plug draining of the tank involves fuel down the arm usually.
Instead it is smart to break the fuel system into 2 halves, perform a delivery check it rules in or out the tank and pump filters and allows you to move on quickly. Many moons ago I was taught to use the "half-split rule" when investigating a problem. Break the issue into 2 bits, in this case if delivery to front carb is good, them move to the second half. Then if that half is good, head around to the other side of the engine. This use of this rule served me well through 44 years around aircraft, I still use it today. I just used it yesterday when Facebook was down. I did not call my ISP, instead I went to website that I have not been to before, that worked, so I was aware of where the issue lay. Good luck with this issue. Peter |
| P G Gilvarry |
| And just for my info, how long does a good working TD or TF pump take to fill a quart jar? |
| John Quilter (TD8986) |
| Todd,
After sitting for several years I was getting my TD back in running order last year. I drained the gas tank and put in fresh gas and installed a new SU solid state fuel pump and rebuilt the carbs. When I did a test drive I had the exact problem you have. When I did the fuel delivery test that Peter described I got LOT of air bubbles coming out with the gasoline which indicated an air leak on the incoming fuel side of the fuel pump. After comparing the old and new Inlet fittings on the SU fuel pumps I found the new fitting was not as deep as the old one and the my copper fuel in would bottom out before the compression donut could seat thus letting in air. I just used the old inlet fitting. With the flow test I was getting about a pint of gas about every 2 1/2 minutes, after fixing I got a pint in about 40 seconds. That fixed my problem. Best of luck, Steve |
| steve hillerman |
| John, Flow rates for SU fuel pumps https://www.dbraun99.com/Dave%20DuBois/Fuel_pump_specs.pdf Best of luck, Steve |
| steve hillerman |
| Thank you all. Some great places to start. I did put stabilizer into the tank before I store the car last year, and actually use Startron stabilizer with every fill to help absorb any water. Peter is right, the only way to address the fuel pump is after you have dumped gas down your sleeve. I will empty the gas tank and check the connections compared to the original fuel pump which I still have on hand. |
| TR Hammond |
| Why do people always drain the tank by removing the plug? You have the cleanest method available, an electric pump. I always pump my tank dry with the cars fuel pump. If more that 20lts I just empty the can into another car and keep going. That way you have minimal fuel in the tank when you remove drain plug. |
| B W Wood |
| There is a screen filter in the inlet of each carb and another one in the bottom of the fuel pump. Any or all of these can get plugged up and (on the TD at least) they are easy to remove, check and clean if necessary. Also check to see if someone installed an in-line filter (not recommended by many but I run one). This keeps the other filters clean but can clog up quickly. Mine is conveniently located under the bonnet and I have to clean it about twice a year. I know my tank is full of cr@p but I dread removing and cleaning it. Maybe someday but for now the in-line filter is not difficult to clean and it keeps me going.
Jud |
| J K Chapin |
| Any thoughts on using plumbers tape assuming Steve is right on the inlet air leak? |
| TR Hammond |
| I have gone through and tried everything l ised above. All filters are clear, when try the fuel dive method Peter outlined, no bubbles in the gas, looking in the tank, it is clean. I replaced the inlet fitting as well. I am still having the same problem. It is like the pump isn't pumping fuel fast enough when climbing a hill. All I have done is install a new fuel pump. How would test the fuel pump to see if it pumping at the correct rate? |
| TR Hammond |
| Todd, Reading through this thread, I have some questions. Is the fuel pump which you replaced, an SU or some other make? If it is SU then what is the part number? You may have fitted a low pressure unit instead of the required high pressure pump. the SU part number should be prefixed AZX the low pressure units are prefixed AUA. The part number is stamped on an aluminium plate on the pump body. John |
| J Scragg |
| The pump should deliver slightly over 1 pint/minute, so a mark on a jar for 1 pint, pump for one minute, see how much you have. For a rear mounted “HP” pump the figure 1.1 pint/minute. It would probably do even better. Peter |
| P G Gilvarry |
| John, You have just saved me additional sleepless nights trying to figure this out. I just checked the stamp on the old pump, and it has the AZX prefix, the new pump AUA. I will see if I can return this, as it was the only TF they sell. I should have noted in my previous notes, but the one thing I did notice about this pump is it seems to cycle a lot slower then the pump I just took off. Thank you, Todd  |
| TR Hammond |
| Slow cycling is a sign of a blockage/restriction. I know it is messy, but try pumping from a container directly back into the container and see the rate then. Also, if you have done any work on the carbs, check that the down stop on the float lever is not set too high reducing flow at high load. Ray TF 2884 |
| Ray Lee |
| I'm going to try checking the fill rate later on this evening. I called where I purchased the pump, they only sell the low pressure with the AUA prefix. They do not feel that the pump is the issue, I never had a problem with low pressure pumps, delivering 1.5 PSI. Called another major distributor, they only sell the azx pump which delivers 3-5 PSI. I then called a nearby British auto repair shop, they sell the AZX Pump, and feel it could be a coil issue. The person I spoke to feels that 1.5 psi should be more than enough. I keep leaning towards the pump. When I lose power going up the hill, if I push the clutch in for 3 seconds, Powers then restored for a little while.
Todd |
| TR Hammond |
| As I've put before, I've no idea why some paid extra for an SU label on the pump when they could have a fit and forget Hardi pump (dual polarity, deliver the fuel required) often at much lower cost and decades of trouble and service free use. MG pumps from 1953 on. - https://www.hardi-automotive.com/en/products/fuel-pumps/ |
| Nigel Atkins |
| Nigel Any thoughts on why they only list MG from 1953 on? Was there a difference after during/after the TF than the earlier MG's? |
| Bruce Cunha |
| Good question Bruce, the first TFs had the fuel pump up the front like the TD.
Then the HP version was installed above the rear axle, LP and HP being relatively little different, but apparently the LP is a sucker and the HP is a pusher. I have seen a few dead Hardi pumps, apparently parts are not easily available. I have a backup FACET, and are getting a stock of SU pumps in place. I looked at the Hardi site and the MGA is the earliest MG I could find, it uses the HP pump like the later TFs I believe. Peter |
| P G Gilvarry |
| Bruce,
I'm very sorry, on looking again that was my mistake, I misread it, it's probably all MG models up to 1953 (I thought it was odd given the company started in 1938). Note - always treat all database and sources of information (especially mine) with caution and cross reference the information with as many reliable sources as possible. MG all models —1953 1112-1 [Hardi number] - https://www.hardi-automotive.com/en/comparison-list/manufacturer-from-great-britain/ AUA 25 shows as 1112-1 / 3312-1 AXA 13** show as 9912 - https://www.hardi-automotive.com/wp-content/uploads/Hardi-Liste.pdf Overview of pumps and what the model numbers mean - https://www.hardi-automotive.com/en/products/pumps-1224v/  |
| Nigel Atkins |
| Peter,
just contact Hardi, I found them very helpful. MGA owner put he'd had his IIRC 30 years of use without any hassle, IIRC you're suppose to put a fuel filter before the tank, I've never bothered as the tank(s) weren't that old. Unless you're the bloke that didn't think there English was good enough in which case either shout loudly as type an email or brush up your spoken German. 😄 I have found SU parts difficult to get hold of, especially from Burlen SU and have found them particularly difficult to talk with despite them being in the same country as me and only 100 miles away and talking the same language their understanding of customer service seems to be - take it or leave it. |
| Nigel Atkins |
| My only dealings with Burlen were pre-Brexit and pre-Covid.
Both worked out OK for me. The Hardi pumps were not mine, saw them at a class, owner had not had success, but then I don’t think he tried Germany. I found a FACET with 1.5-4.0PSI that I am using as a inline series pump. I have a selector switch and use the pumps alternately. Tom Ball did tell me uses 2 SUs in series with a switch to select. If the FACET ever fails I may do that, not right now. My German is very limited, but Google translator works well these days. I will tell my friend to try Hardi in Germany. Thanks, Peter |
| P G Gilvarry |
| Does anyone feel the the LP vs HP would deliver that much difference (1.5 PSI VS 3.0 PSI)? As I had said, the var was running great until the pump change. Three suggestions: *retard the timing *check the exhaust for loose parts block exhaust flow *change the coil Any thoughts? |
| TR Hammond |
| Some questions that might put us on a different tracks. What was the failure of the first pump ? Was it really failed ? Finally the new pump doesn't work also. But the symptom is somhow different. Check for electrical supply, connections, ground. I understand that you'r still using the one year old fuel. What about trying a brand new one ? Not easy I know. Coil : good idea. At high rev, the battery powered ignition system needs more energy. Check also for points gap. Laurent. |
| LC Laurent31 |
| Laurent,
The other fuel pump just quit. It had been giving me a little bit of a problem over the past couple years. the points were shot and it was 15 years old. I did put new fuel into it the other day, still ended up with the same issues. It does do a little bit of bucking and hesitation if you are on a straightaway for a few minutes and then try to pick up speed. But nothing like going up a hill where it loses power, and Dez do a little bit of hesitating and bucking. I know everyone keeps saying that it's not the fuel pump, which I hesitate at only because you're really ran like a top before I replaced the fuel pump. Todd |
| TR Hammond |
| You have the wrong fuel pump which puts out 50% of the correct pressure. Why bother doing anything else other than putting the correct pump on? As stated above, one is a pusher and the other puller. If that doesn’t fix then check other things. George |
| George Butz III |
| George, that is what I have said but keep getting told that 1.5 psi is enough. |
| TR Hammond |
| Get you original pump rebuilt by Tom Ball, the later TF had a different pump for a reason. If the LP pump would do the job they would have used it, or add a backup pump, no more than 4.0PSI. Peter |
| P G Gilvarry |
| Tom Ball in Copley Ohio? I will give that a try. I am sure cheaper than $270, especially after spending $200 on one. Thank you. |
| TR Hammond |
| Yes, do you have the details? Peter |
| P G Gilvarry |
| 1 psi will raise water 2.31 feet, so 1.5psi would raise a 3 1/2' column of water. Gasoline is roughly 3/4 the density of water, so a 1.5 psi pump should raise it a little over 4 1/2 feet.
Time the pump output with it on the level. Next, jack it up, put it up on ramps or elevate the front end any way you can, and then time the pump output. There probably won't be hardly any difference, unless the pump pressure is not up to spec. I'd suggest popping the gas cap before the next run to make sure the fuel tank isn't in a vacuum. Next time it acts up running up a hill, pull over and pull plugs; you may find a front or back pair of plugs wet which will narrow down your detective work. You don't have the oil bath air cleaner, do you? Double check the oil level if you do. A club member complained his T car was running rough on acceleration even though it idled fine. He'd just overhauled his carbs, so I asked if he checked the oil bath's level. "It's perfect." A month later at the next meeting, he said "You'll never guess what my problem was- it had too much oil in the oil bath." I'd never have guessed! |
| JIM N |
| Peter, yes, I found him through a web search. Jim, interesting thought that I will try regarding raising water. It makes sense it would take more PSI to push gas uphill. As for the oil bath air filters, no I do not have those on this car. Todd |
| TR Hammond |
| I don't know what the main reason is, I didn't have that problem until one day it appeared, I removed the oil air filter cap and it was fixed. Now I have two air filters, one on each carburetor and the car is going very well. For some reason not enough air was getting into the engine. |
| Gabriel Martínez |
| Tod, Abingdon Spares, down here in Deep River Ct has TF pumps for 179.95,,, give them a call with your problem,, 800-225-0251 Steve |
| SPW Wincze |
| Todd, Gasoline is "lighter" than water, less dense, and will rise higher than water for a given pressure. Certainly 4 1/2' of lift is more than adequate to reach the carbs. That assumes you have 1 1/2 psi. |
| JIM N |
| Jim, I fully agree with your hydrostatics but fear the problem may be related more to flow rate than to hydrostatic lift. The symptoms described seem to indicate that enough flow is available to maintain adequate fuel flow at low demand (level cruising) but not at high demand (pulling hills). This is exactly the same as mine does when my in-line filter starts getting clogged. I suspect something is inhibiting the fuel flow to Todd's carbs. Best test may be when it happens to pop the tops off the float bowls and see if the fuel level is low. I wonder if it could be something as simple as a crimped or bent fuel line.
Jud |
| J K Chapin |
| Steve,
That is where I got the pump, and. Had a long conversation about this. They do not think that the pump is the issue. The carbs rebuild a year ago, all lines appears clear, all filter screens clear as well. I keep going back to the fact the Carr had no issues climbing the same hills a month ago. All I have done is Change the pump from a high pressure to a low pressure. NOW When the demand for climbing power I have issues. I had a good discussion with Tom Ball, as previously suggested. He has suggested rebuilding the pump for high pressure. Todd |
| TR Hammond |
| Todd, I had the exact problem on the MGA, it was a crack in the line between the tank and the pump. It may be that on the level, the vacuum required to draw the fuel to the pump is not enough to suck air in through a crack or a leaking fitting, but on a hill it may draw in air due to the extra vacuum in the line.
Our TF always had a Hardy pump. It looked a lot like the SU, worked fine, but definitely had a louder click than the SU, more of a thud than a click. About 20 years ago dad brought it to an “expert” who charged a fortune to “fix” it. I had to overhaul everything to make it run again. The Hardy pump was gone, and replaced with a LP SU. The LP SU has done an acceptable job pushing the fuel. I still think you have a stubborn air leak. Be well, David |
| D. Sander |
| Todd,
if you've got any old rubber fuel hose or just as likely to fail new rubber fuel hose, particular if covered by braid so yo can't see condition, then it might be breaking down internally causing a restriction but perhaps not enough to have small debris showing up inside a filter or elsewhere. Moss Europe sell Teflon interior s/s braided hoses so bling and very practical, guaranteed for life, and low prices. I'd have to dull and dirty the bling element. I wish such hoses were available for my model and for domestic water tap connection too instead of the ultra cheap rubbish that's sold here. |
| Nigel Atkins |
| There's a fair bit of confusion going on here
The facts are----- Basically speaking there are two(ormore) SU pump styles There are low pressure pumps, commonly refered to as suckers--these are normally mounted up in the engine bay and suck the fuel up from the tank and deliver it to the carurettors at low pressure- Then there are high pressure pumps -these are normally mounted at the rear near the tank and pump the fuel under pressure up to the engine Problems--- If a high pressure pump is fitted up at the front of a car that normally has a low pressure pump it will probably flood up the float bowls If a low pressure pump is fitted at the rear of a car that normally has a h/p pump back there the pump won't be capable of suplying enough fuel from that position Your mgtf with the pump at the rear needs a high pressure pump The low pressure SU pumps are more of suckers than blowers and can't supply fuel up to an elevated position You need a HP pump , before you burn some valves out from lean running willy |
| William Revit |
This thread was discussed between 05/10/2021 and 05/11/2021
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