TR6 TR6 will not start back up after being run for a while and engine warm

[bighealeysource]

Hey TR6 guys and gals,
Got a buddy with a 76 TR6, very nicely restored, had it for quite a few years. He is now having a problem with it not wanting to start after driving it for a while and then once he stops for whatever reason and shuts it down, won't start when he goes to restart it. By that, if he lets it sit for maybe 30 minutes will then start, but not when hot. He's gone over entire ignition system, changed the coil ( my thought for the culprit), believe even put on some kind of heat shield over the gas line in case the gas was boiling from the exhaust manifold heat. Runs like a champ when running, starts up pretty easily. Just won't restart when warm. Any ideas ?
Thanks,
Mike

 

[Gliderman8]

The coil could be bad when it heats up... try swapping a known good coil or a new one.

Edit: I just re-read your post and see you already changed the coil

Have you verified that the fuel pump is working and that there isn't a clogged filter or crud in the tank?

 

[NutmegCT]

Others with more experience than me will soon reply, but here are some quick thoughts:

When the problem occurs, will it start again immediately if you pour cold water on the fuel line between filter and carbs (vapor lock)?

Replace the distributor condenser. Cheap and worth it to see if the condenser is failing.

If it cranks and sparks the plugs, but won't "catch" - If you spray starter fluid in the carb throat, will it fire then? (another fuel flow test)

Edit: others with more experience DID reply!

Tom

 

[TR3driver]

Was the weather kind of warm when this happened? if so, my thought is that the heat shield was in the wrong place. Try a temporary shield between the exhaust manifold and carbs.

https://www.the-vintage-racer.com/index.php/carburetor-componenets/product/36-shs-tr6

I don't understand why, but it seems that fuel at least in CA has become much more prone to boil in the jets (percolation) than it used to be. We made a 10 minute "pit stop" during a club run up the mountains, and every Triumph in the lot was sputtering and blowing black smoke when we started up to leave.

 

[toysrrus]

Hi Randall,

I have to presume you folks out in Cali have "Non-Ethanol" feul; Correct? Thats all I`m running in my "John Deere & TR3" and happy to say; All is Well.

Russ

 

[TR3driver]

Nope, can't buy it here, at least not for road use. We've only had "oxygenated" fuel for a lot longer than most of the country; although they used to use MTBE instead of ethanol. The local authorities seem to feel it helps reduce pollution. I don't believe that, but I have to admit that the air is a whole lot cleaner now than it was 30 years ago and it's nice being able to see the mountains most of the time instead of just a few times a year.

But ethanol itself doesn't boil all that easy, and at least from what I've seen, the problems with percolation seemed to get worse several years after they started using ethanol instead of MTBE. So I think there is something else going on. The RFG II program closely controls a lot of gasoline parameters, including boiling point, and I think they are just setting the boiling point (aka Reid vapor pressure) too low for good operation in cars with float bowls exposed to exhaust heat. Joe A (who offers the heat shield I linked to above) said that a lot of folks reported better fuel mileage after installing his shield, which makes me think that a lot of folks are having the issue and don't realize it.

 

[JerryVV]

A friend has a TR6 and had this same problem. When it happened on one of our trips I noticed that his fuel line was in contact with the oil filter canister. My guess was when the engine was turned off that hot canister heated the fuel enough to cause vapor lock. They discounted my guess but I stand by my thoughts since when they loosened the fuel line between the carbs and the pump alowing some fuel to escape the car started. No problem as long as we were driving at highway speeds. They later blamed it on a bad fuel pump. That doesn't explain why it ran fine from cold and when running at hghway speeds.

 

[RJS]

Here's one more theory. I experienced a hot start problem just like that for over a year. No matter the abient temp outside. Finally diagnosed it with overly rich carb adjustment. So it was like starting a hot engine with full choke. I guess it didn't like that

Unqualified mechanic was the cause

Bob

 

[bobh]

Does the engine turn over? It just won't fire?

Back in the mid 70's when my TR6 was my daily driver I had a problem with the engine not starting when it was hot. In my case the engine was hot and it was summer. After sitting a while the engine would start.
I honestly can not remember if it turned over but would not fire. Or if it didn't do anything. After checkiing everything I could think of during the month or so the problem existed. I eventually replaced the battery and the problem went away.
I never had any indication of a bad battery. Never had the battery tested. Just bought a new one.

 

[NutmegCT]

Mike - could we get a reply from you on our questions? Hard to help when we dont' know what's up.

Thanks.
Tom

 

[bighealeysource]

Hey guys,
Sorry, I always try to reply back with advice on trying to help out with one of our LBC's. I am going to have the owner of this TR6 either reply or let me know the answers so we can see if any of the ideas have been tried, worked, etc.
Thanks,
Mike

 

[ColemanWhite]

Thanks for the ideas regarding my TR6 hot starting issues. Seems like some good suggestions and I will take them one at a time. Will let everyone know what worked.

 

[tdskip]

Thanks for the ideas regarding my TR6 hot starting issues. Seems like some good suggestions and I will take them one at a time. Will let everyone know what worked.

Welcome, and keep us posted.

 

[Paul73Tr6]

I had this problem with my 73 tr6 it turned out to be electrical problem I bypassed the ballast wire and bought a new coil.

 

[Paul73Tr6]

I had this problem with my 73 tr6 it turned out to be electrical problem I bypassed the ballast wire and bought a new non ballast coil

 

[Tosh]

Wasn't there a previous thread on this very same issue?
Anyway, I had this issue a couple of years back and the short term solution was to depress the throttle the whole way while cranking. The thing would usually light.
The long term solution for me was to set dynamic timing at 14° BTDC (from 4° ATDC static). It will now fire almost instantly hot or cold.
It runs great with no detonation.

Keep on'.