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MG TD TF 1500 - Will not fire when hot

This is my first post but I have gained a great deal reading here in the past, thank you.
My TF1500 will not start when hot, I need to open everything up and wait for 10+ minutes and she will fire up and run just fine. When I say hot I mean normal running temperature. It is a bit of a pain stopping to get fuel. Car runs well otherwise.
I have set points, timing, spark plugs, and a set up on the SUs. Still the same.
My next line of attack will be the starter, just I encase the bushings are causing it to draw excessive current.
Thought I should ask the experts, any ideas?
Thanks
Don
D Hanna

You need to advise us if the starter cranks the engine over but it will not fire, or the starter fails to operate.
John Quilter (TD8986)

Two components that have shown issues of that type are the capacitor (condensor) and coil. Have you tried the technique of pulling out the choke? Bud
Bud Krueger

Check the archives here for "Vapor Lock".
A very common problem, (more so with the TF), and a lot of different opinions for the "cure".
David Sheward

Don; Where about are you in Ontario. If you are close I would come give you a hand. It sounds like a heat soak (vapour lock) problem. Try Bud's suggestion of pulling the choke for a bit to get fresh gas in the carbs.
C.R. Tyrell

Easy way to confirm "Vapor Lock / Heat soak" is the problem.

Purchase a couple of those "cold snap packs" from a drug store. Next time this happens, snap them and wrap around the carbs. If it starts right up, that's your problem.
David Sheward

Thanks for all the help.
The starter still cranks the engine, perhaps not as fast.
I have not tried pulling the choke. My first thought was it was running rich which is why I adjusted the floats and SUs after the points, timing, etc. I will give that a shot tomorrow, will are having a storm coming in now.
I will check the coil and cap., had not considered that as it runs ok and starts well when cool.
Well sounds like the group experience shows it is vapour lock/ heat soak.
My mga had a heat shield and I never had this problem but it sounds like a shield will be no help with heat soak.
C. R. Tyrell, I am near Simcoe. Are you going to Bronte?
Thanks again everyone.
Don
D Hanna

Vapor lock.
I don't know what the ethanol content is in Canada, but it is going up to 15% in the states, and vapor lock will become worse.
As fall temps drop, you may not experience it again, this year.
I mounted our stock pump plus a Facet pump under the fuel tank in back to alleviate vapor lock. Still had episodes this summer in 95F degree weather on the highway.
Just expect to pop open the bonnet after a brief shutdown in hot temps. If you're desperate, you can break a fuel line loose downstream of the pump and let the pump run to vent gas vapors and mist spray all over the hot engine until the pump primes... or just wait.
Adding an extra pump under the gas tank to push fuel forward, with remote switch, is not a bad idea. fuel pumps aren't the most reliable component, anyway.
JIM NORTHRUP SR

Leaving the bonnet up on the carburetor side of the engine while the car is parked will normally stop the heat soak from occurring. As Dave S. suggests, check the archives under both vapor lock and heat soak. I recently posted the results of my taking temperature readings on the channel between the float bowl and the carburetor jet on our car after having driven it hard on a hot day. I will be posting more results of other such drives whenever we have a hot day in the Puget Sound area, which will probably be sometime next summer (we had some record setting temperatures today, but was busy with other things). I intend to install a temperature controlled bilge blower ducted onto the carburetors in an attempt to control this situation. Cheers - Dave D.
David DuBois

My bet would be the coil.
Larry Brown

Although heat soak is a very common problem with the T series cars, Larry could be right on the button. It is at least worth the cost of a new coil to check it out. The fact that you said that pulling the choke out didn't help getting the car started would indicate that perhaps the ignition side of the equation is where the problem is. Cheers - Dave
David DuBois

Don,

It could also be the first sign of your rotor arm shorting.


John 52 TD
J Scragg

Great ideas I will check them all.
I did not consider the coil, cap. and rotor because the engine runs ok and normally starts fine, but will sub them out.
One of the first things I did with the car was remove the tickler pins and fill the holes. I was concerned about the fuel boiling in the float chamber and overflowing onto the hot exhaust. Guess I should have checked heat soak for this problem..
I tried leaving the bonnet open, starting the cold engine, letting it run until it reached full temperature then shutting down. It would not start again for about 10 minutes . Engine was running very rich so I did a tune up.
Have not had a chance to get to it yet today but will report if anything works.
Thanks again
Don
D Hanna

Don; I am in Brantford, and I will be in Bronte on Sunday. I will look for your TF, and I will be there with my TD.
C.R. Tyrell

"remove the tickler pins and fill the holes"
hmmmm ...would doing that have an effect if dash pot caps are not vented?
Just wondering.
David Sheward

Nope...believe that's a different part of the carb, David. Lots of the caps come without tickler pins...just solid.
Gene Gillam

Gene ...you mean without "vents" ...right? (on dashpot caps.) I have both styles.
David Sheward

C.R., hope to meet you at Bronte.
David, both pots are internally vented but one of the caps was also vented. Filled that hole with 14ga copper wire.
I also cleaned out the overflow lines on the float bowls.
Replaced a couple of missing springs on the linkage. Replaced fuel lines and screen filters. Checked fuel pump flow and pressure.
This all prior to posting here.
Plan on trying all suggestions here and refilling fuel tank with known low ethanol gas.
Don
D Hanna

Don,

If you have removed and or sealed the tickler pins on the float chamber lids be certain that the washer under the overflow banjo is not a tight fit. If necessary file notches in the ID of the washer so that vapor or fuel can pass into the banjo and out the overflow tubes when necessary. The notches are present if you have the correct washers but many have been replaced by POs or mechanics that did not leave a path for overflow.

Best regards,

Jim Haskins 1953 TD
J. M. Haskins

Dave,

I know you were talking about dash pot caps but I was talking about float bowl covers. Whether they have a tickler or not, and a number of them don't, they are still vented via the overflow tube. There should be a fiber washer with flutes (?) on it under the overflow connection that allows the cap to vent.

Gene

Gene Gillam

Yes the washers are fluted for the overflow.
Well good news and maybe bad.
We took the car out to night and went for a drive perhaps the longest drive the car has had in 20 years, still not that far, less than an hour. Pulled into the garage, shut it down then started right back up without issue. I wanted to try the enrichment control to see if that helped but it started without doing anything. First time while hot since I have had it.
On the down side, the starter cable broke when I pulled to start the engine. Checking closer I see it has melted in several spots and burned holes in the carpet. Checked with a volt meter and find full voltage on the bracket the holds the starter switch and former starter cable. I had a little welder frying the cable! Turns out the starter switch had a short to the case. There was enough paint to act as insulation between the bracket and car body that it did not short directly to ground and full current flowed though the cable. Could have been exciting! Installed new starter switch that I had for a mga. Did not have a spare starter cable so now need to start the car from inside the engine compartment. Have ordered a new one but hope to pick one up at the Bronte British car show on Sunday.
Thanks again everyone for the help
Don
D Hanna

Don; I think I have an aftermarket cable that could be used until you acquire a new one. Send me an e-mail and maybe I can get it to you.
C.R. Tyrell

Hi C.R., thank you very much for the offer, that is very generous.
I was able to get a replacement starter cable today and hope to install it tomorrow (Saturaday) in time for the car show. Hope to meet you there.
Thanks again.
Don
D Hanna

This thread was discussed between 12/09/2013 and 14/09/2013

MG TD TF 1500 index

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