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MG TD TF 1500 - spits and sputters

When cranking my TD cold, I pull the choke and it starts and purrs like a kitten.

After driving five miles for gas, when I turn it off and it sits for five to seven minute, when re-crank the car it spits and sputters.

I have a pertronix electronic ignition. The rotor button appears to be in excellent shape.

Before rebuilding the SU carbs and they were sucking a lot of air I didn't have the problem. Now, I do.

Open to any suggestions. I've approached the problem from several ends. The voltage regulator is the only thing I've not thoroughly investigated. The Pertronix is new.
R C Flowers

Before you tear your engine apart and rebuild it, observe the issues and watch for repeated episodes.
There are lots of arguments over vaporlock, but if your problem only surfaces after short shutdown and restart on hot days, then consider it is a transient from, as described on this forum, "heat soak."
Five minutes doesn't sound like it is long enough to incur, unless it was uphill at 75mph.
Yesterday, I started measuring temps via thermocouples under the bonnet and it was pretty interesting. After pulling off the highway and stopping at a light, the air temp in the region of the floats rose to 255F. Pop the bonnet, let it cool off for a few minutes and restart with choke.

Thank you Jim. I thought I might advance the timing slightly, or re-adjust the carbs for the summer heat and humidity but I wanted more input before proceeding.
R C Flowers

That sounds exactly like the hot day shutdown/hot soak vapor lock my car has done on hot days since the 70's. I agree with Jim that is a little on the short side as far as time, but possible. Easy to tell: pull the choke. If it greatly improves, that is the problem. Wow, 255 degrees, bet that will boil anything out. George
George Butz

Hope you added quite a few gallons of SUMMER gas. Lot of vaporlock complaints early spring/summer can be due to WINTER formulation of much more volatile gasoline.


I'm running pure gasoline and I'm adding a lead substitute. Sometimes after driving and the car is idling, it will start to drop in rpm's and will sputter.

When I use the choke to start the car, when the engine is already warm, it acts as though it's flooding.
R C Flowers

I meant to just try the choke when it is or may be vapor locking or running badly, not to start it when hot.
George Butz

I run Ethanol free gas (low octane is all I can get) and with the hot days we've been having (92 - 97 F) I can almost set my watch by when the sputtering will start. Runs great all morning but when I try to go somewhere or come home around 3 pm (hottest of the hot) the sputtering starts. I think it's excess heat around the fuel pump and carb float bowls.

Dave, I haven't removed that fuel filter because I had just filled up and I figure all the fuel will run out when I separate the fuel line going to the pump - right?

I also haven't swapped out the condenser to see if that's part of the problem cause I'm just lazy and am hoping I can get a suitable replacement condenser at NAPA - suggestions? Part number?

I'm really not trying to hijack RC's thread but his symptoms are the same as mine and these were suggestions I received so I hope they are helpful.

J K Chapin

I run gas station swill..lowest octane with ethanol and have never had an issue.
R.C. flowers..leave the lead poison on the retailer's shelf where it belongs. It is doing nothing for your car and just spews poison into the air. For our kids and grand kids not buy that horrible product. Regards, tom
tm peterson

Yesterday, our ambient air temp was only 75F and I documented air temps around my fuel line, just below the point of the firewall; that air temp rose to around 140F by the time the thermostat opened and eventually climbed up to a steady 150-155F on the highway (65-70mph).

I mentioned the thermocouple in the exhaust pipe. For those curious: around 50mph, exhaust temp was over 1000F; 70mph~ 1300F; around 90*mph-1350. To put the latter temps in perspective, most cast aluminum pistons melt somehwere just under 1300F.

*I can't positively declare a measurement was made at 90mph. I happened to look at the tach (which is also our fairly accurate speedo) and notice it was up around 4500rpm which translates into 90mph. I had the GPS for accurate speed/temp measurements on the trip over to the party, but, unfortunately, stashed it behind the seat for our return home.
I asked my wife why she was driving that fast... her answer, "Because I can!" She doesn't usually cruise that fast, sober.

JRN, funny.
R C Flowers

Funny? ....not if you're the navigator!

This thread was discussed between 22/06/2014 and 23/06/2014

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