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MG TD TF 1500 - I think I have vapor lock?

Help -- went to a car show with my 1952 MGTD. The temperature was 75 degrees outside. The car ran great with running temp at 80 degrees. I pulled into the car show and shut the car off. I then had to move to another spot and tried to start the car. The fuel pump clicked very, very fast, the car started but it kept on popping thru the carbs and could not get past a slow idle. I had to work the gas pedal to keep it running and that was just barely running -- all that time the engine was backfiring thru carbs and i could hear the fuel pump working. We sat at the show for 3 hours, the car cooled down as well as outside temperature and car ran like a champ. i am assuming I had vapor lock? Has anyone experienced this situation with your car and does anyone have a recommended fix? Thanks as usual. Russ
Russ Little

Very common. Much has been written, so you might check the archives (doesn't usually work for me though). The temp under the bonnet can exceed boiling temp of gas, leaving fumes instead of liquid, which the pump has a hard time pulling uphill.

I always carry small adjustable wrench in my pocket, and will sometimes grab a plastic bottle or receptacle of any description, run out a pint or less of gas at banjo fitting or line nut on pump outlet or carb, snug it back up, then go (after redeposting the gas into the tank).

I have relocated pumps (plural) in back below the tank to avoid just this issue.

Jim Northrup

Next time it happens Russ, give it full choke until it smooths out. That will usually get you going.

YUP, LaVerne is spot on,,,,a little choke wil start it right up,,,


It's more common with Ethanol in the gas and it's lower boiling point. PJ
P. Jennings

Definitly a subject that has a lot of info in the archives and worth the read.
I fought this battle 10+ years ago, but have not had it for over 10 years now.
Let me know if you can't find the thread concerning how I ended it and I will try to find it.
search archives for Vapor Lock (around 2001?)
David Sheward

the choke is the key.
as you may know,but if not, in a variable venturi carb like the S.U.'s "working the gas pedal" is not going to work like a fixed venturi carb with an accelerator can probably relax your foot. regards, tom
tom peterson

I discovered this on my first trip , over 100 miles....
Pulled into a gas station, and couldn't get the car restarted until I choked it...
I even considered putting a heat shield behind the carbs, similar to a "B"....But, it's easier to choke on hot restarts.
E.B. Wesson

Thanks for the input --wrench is in the glovebox already and choke cable is ready to pull. I also added a on/off switch to the electric fuel pump with the switch hidden in back of the glove box. Some research suggested to switch off the pump and let carbs run dry as car shuts down. This will take vapor lock out and just need to switch it on prior to restarting. It is also a nice theft feature plus good to run carbs dry when car is in storage -- especially with this new fuel we are getting. Hope this works!
Russ Little

This thread was discussed between 03/03/2012 and 06/03/2012

MG TD TF 1500 index

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