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MG TD TF 1500 - Fuel Pressure Regulator?
|My car came with a fuel pump that looks like the Moss catalogue "Solid State Fuel Pump" (page a22 in current book) I am going to replace it with the same or something I can find at the local parts store for a reasonable price. Being a TF the pump is under the rear deck and is not visible.|
I have freshly rebuilt carburetors and I would think that the needle valves would control the fuel pressure from any "standard" pump. However a friend suggested I add a pressure regulator to drop the pressure down to a few pounds.
What's the collective wisdom of adding a regulator to the system?
|The carbs are set up to work only with LOW pressure pumps (about 2 lbs/sq.in.. Most that you would find at your local auto parts store are at least 10-15 lb/sq.in. output pressure. So, unless you are sure you have a suitable low pressure pump, you must have a pressure regulator.|
Otherwise, you will have a huge puddle under the car and probably a nice warm fire.
|Ray - I assume that you are referring to one of the little, run all the time, make a lot of noise, Facet pumps that is mounted in your TF. If that is what you had in your car, have you checked it to see if it is working? If it is, there is probably not necessary to replace it. If it does need replacing, see the article, Back up Fuel Pump under the SU Fuel Pump section of my web site at: http://homepages.donobi.net/sufuelpumps/ for information on purchasing these or other appropriate pumps from NAPA and half the price that Moss gets. You need to ask of the low pressure 2.5 - 4.0 psi version of whatever pump you get (the original SU fuel pump for the late TF has an output pressure of 3.8psi). If you can't find the pump at NAPA or other good auto parts stores, You can get it from Pegesus Racing at: http://www.pegasusautoracing.com/advcat.asp?CategoryID=AIRFUEL|
under part number 1103. Cheers - Dave
|Thank you David and everyone else. |
At the time I was waiting for the tow truck there was no noise from the fuel pump. No clicks, rattles, hums, burps...nothing. I pulled the fuel line at the carbs and no fuel.
Today I turned the ignition switch and the familiar clattering sound and fuel from the carb line.
I am guessing I have a intermittent problem. Situation occurred right after getting the car's first full tank of fuel. So a vacuum is not the problem, and the car's only been driven a total of 3 miles. Fuel system was flushed and cleaned before first start of the engine last weekend. And everything seems to be running normally this morning.
I am thinking of leaving it in and installing the new pump in line as the back up pump so I can test the failure mode of the original pump before replacing it.
|Pulled the fuel pump and bench tested it. It failed in about 10 minutes. Not worth putting back in the car so I took it apart. Not much inside. Everything is incased in a plastic foam and must be destroyed to inspect. |
The pump consists of a wire coil surrounding a tube. The pump action is from a metal slug that vibrates back and forth in the magnetic field created by the coil. A spring loaded check valve controls the flow of the fuel. At the bottom of the foam/case is a small circuit board that most likely develops the alternating current to energize the coil.
Not much to break or wear out other then the check valve or something failing in the electronic circuit.
My guess is that something on the circuit board was sensitive to either the vibration or heat and would fail after a few minutes. Once cooled down or enough time had passed it would return to normal, as all the parts within the "pump" section appeared to be wear free.
|Ray - It depends on the age of the pump. the little Facet pumps are as reliable and any other pump, but they do have a finite lifetime. |
"Situation occurred right after getting the car's first full tank of fuel. So a vacuum is not the problem, and the car's only been driven a total of 3 miles"
A vacuum will be formed real soon after filling the tank with fuel if the vent is clogged since there is very little head of air above the fuel in the tank when it is full. 3 miles is about the distance at which the vacuum will form when the tank is full. That said, I doubt that this was the problem in that the pump was quiet and a Facet pump will continue to chatter away regardless of any clog or the needle valve in the float bowl being shut off - that is why they are so annoying to listen to. Cheers - Dave
This thread was discussed between 21/06/2008 and 22/06/2008
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