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MG TD TF 1500 - TF Overheated Fuel Pump ??

The fuel pump is located in the rear. 4 times in the past month the fuel pump sops sending fuel and just does a tic tac tic tac continouslyv, sending air and not fuel. If I let cool down the fuel pump it starts woking again.
Is it the diapragm ??
How can I solve the problem ?
Thanks in advance
Jose Vicente Vargas

Jose - You may have an air leak on the inlet side of the pump, either in the line from the tank or in the pump itself. To check for this, disconnect the fuel line from the carburetors and direct it into a container, then turn the ignition on and check the stream of fuel coming into the container for a lot of air bubbles. If there are bubbles in the stream, you get the fun of disconnecting the fuel line from the tank to the pump and plugging the line for the next test. Connect a flexible line from the inlet side of the pump and drop the end of the line into a can of fuel, then repeat the test above - if there are still bubbles in the stream of fuel, then the problem is in the pump; if not bubbles, then the problem is in the line from the tank to the pump.

You state that the pump is getting hot, which can be the result of air in the lines, causing the the pump to run very fast and heating up over time or it can also be caused by a clog in the fuel line from the tank to the pump or the vent in the filler cap being clogged and a vacuum being formed in the tank. To check for any of these situations, see the article, Fuel Delivery Troubleshooting Guide in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave
David DuBois

Sounds like vapor lock, especially if you run gas with ethanol down there. What's the air temperature?

You say it is in the rear, but is it located down low or up high?

Especially if the pump is up above the fuel level, it is likely vapor locking. As it tries to suck fuel, hot gasoline can vaporize and the pump just chatters.

I prefer installing the pump under the tank in the rear so it is gravity fed liquid gasoline at all times.

As Dave points out, restriction from the tank to the pump will choke the supply leading to vapor lock. Pull the tank fitting and check for rust in the strainer, an accumulation of rust in the fitting or low points in the fuel line. Pump strainer, too. I've lost fuel feed due to rust in all those locations. Blow the line out. If you find rust in the rear, you might as well clean the float bowls and strainers to the floats.

Open gas cap in case the vent is plugged.

Also, try pushing the tickler down on the float with pump running to relieve any gas pressure buildup from the pump to carb and listen for the pump to slow down as it sucks liquid. It may spit some gas out of the tickler so watch out, you might want to catch it in a rag, especially if it is a TF. What is preferable is to remove the line to the carb and run the gas into a container, then you can run some cooler gas from the tank through the system, too.

Jim Northrup

Jim, On the TFs, at least on the 55s I know, the fuel pump is located in the rear right hand side, attached to the frame under the side curtain compartment. Most of the tank is above the pumps elevation, not like the earlier models where the pumps are on the fire wall. I think it was a good move as the pump doesn't have to work as hard and should always be in prime.



P S Jennings

Jose,
Real simple first test:
Take a magnet retreaval tool and stick it in your tank. If you pull it out and it is coated with "rust chips" you have found the problem. Tank will need sealed. Many of us run an in-line filter AFTER the pump to safegaurd getting the lines/carbs clogged.
Make sure if you install a filter it is AFTER the pump not ahead of it! Definitly read Dave's paper on the subject ...but this simple test should tell you very quickly if a dirty tank is the problem.
David Sheward

Hi David,
So how is the plumbing for an "after the pump" filter done, given the use of copper line and all those special British fittings? I am going to do it, but I am hoping I don't have to invent the system. I was figuring on putting the filter up front on the TF just ahead of the SU's.
Mike Davis
MW Davis

Mike - Easiest way is to cut a chunk of the fuel line, a bit longer than the filter out and connect the filter with some flexible fuel line pieces. The copper line is approx. 5/15" OD so get a filter with matching barbs. Cheers - Dave
David DuBois

I did mine as David DuBois described....just beyond the pump. I kind of got the screws put to me when my car was painted. They were "suposed" to clean & seal the tank. They did not. I use a clear filter and change it up several times a year till I get around to taking the tank off and fixing it. I also "purge" the pump when I repalce so having it back there works well for me. Up front by carbs would work also but I am braided lines there so the interface was easier for me in the back of the car.
David Sheward

Thanks for the information, gents. I had planned to use a clear filter. I did a lot of gas tank cleaning with some acetone and then a big dose of muratic acid followed by rinsing and a baking soda bath, and more rinsing. Dried it out and then a nice coating of some diesel fuel to prevent more rust. But I am sure there will still be some crap in there, given the baffles that are present. My goal was to avoid repainting the tank, but I dropped it in the process and got a few small dings in it, so I will have to paint it anyway! Mike
MW Davis

Mike,
>>>"Dried it out and then a nice coating of some diesel fuel to prevent more rust"<<<
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Was this done for the storage time before it was mounted and used????.
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SPW
Steve Wincze

This thread was discussed between 02/11/2010 and 03/11/2010

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