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I was in Oregon over the weekend and got my TR8 out for the first time since early April. The weather was fairly hot, about 85 by mid-afternoon. I shut the car off for a few minutes, restarted it, and drove a few blocks before it died, acting like it was out of gas. We pushed it back to my sister's house and left it in the driveway for a couple of hours. It started right up. It nearly stalled on me while crawling along in city traffic the next afternoon, but I managed to keep it running by repeatedly depressing the clutch and revving it. Seems like a classic case of vapor lock.

Any idea why? Is my fuel pump failing? Or could it be the "winter gas" (10% ethanol blend) that I filled the tank with in early April is vaporizing in the fuel line as it passes thru the engine compartment?

Ken
Anchorage, Alaska

1980 TR8, 1973 TR6, 1965 Volvo PV544, 1958 MGA, Jeep Cherokees

Only time I ever vapor-locked my TR7 was in Eastern Oregon, summer of 1990. I'll never forget the sound of gasoline actually boiling.

Ken this was a common problem in Oz in the early post war period, when everyone ran old prewar yank cars, with early 30s Dodges & Chevs everywhere. New cars were just not available.

No rubber fuel hoses available, they had copper pipe all the way from tank to carb. They would have a few coils, [like a coil spring] in the line to absorb movement, without work hardening, & cracking. Most of these had your symptoms, with fuel boiling in the pipes when stopped.

Most cars carried a canvas water bag, hung above or under the front bumper back then. We also carried an old towel. Before shutting down, dad would soak the towel in water, open the bonnet, [hood], & wrap the wet towel around the fuel pipe. This usually worked, & I'd suggest you try it on your car, if only to prove the symptoms.

Then some smart mechanic, [yes there are such things], thought about the problem. He realised you can only get a vapor lock if the vapour can't escape. He realised that if there was a constant rise, with no high points, all the way to the carb the vapor would have to rise to the carb, where it could pass through the float chamber needle valve & escape through the chamber breather.

Most of the systems had the pipe rise above the carb, then come down to the union. Once he eliminated any fall in the pipe the problem was solved. Word soon got round, & in our town nobody still had the problem a year later. Make sure you don't have a fall in your fuel pipe anywhere.

I'd also look for a flooding problem. After the lay off the needles may have become sticky with varnish from evaporated fuel, & not be shutting properly. I've had quite bad flooding stalling the thing, unless the revs were kept up, in the past.

The same thing can happen to the valves in the pump, depending on what it is. If the check valve is sticking open some times it can just work the fuel backwards & forwards, with little getting pumped.

Hasbeen

One more thought, where do your carb breather/overflow hoses go?

I had one 7, with the SU breathers piped to that damn fool vapor canister, [the stock US system with ZS carbs I think]. The trouble was the canister was full of a horrible mixture of water oil & fuel when I bought the car.

Before I discovered this, I could not get the thing to run reasonably, because the carbs couldn't breath.

Hasbeen

The ethanol manufacturer's website included this Q&A:

"Q. Does ethanol cause vapor lock?
A. The vapor pressure of gasoline is set by law – and is lower in the spring and summer than in the fall and winter. Vapor lock usually occurs when a winter grade of gasoline formulated for cold weather starts is used under summer-like conditions."

Seems like winter gas is the likely cause, but I'll check the fuel line and carb overflows when I'm back in Portland for the ABFM. Thanks.



Ken
Anchorage, Alaska

1980 TR8, 1973 TR6, 1965 Volvo PV544, 1958 MGA, Jeep Cherokees

I'm surprised there is much difference between summer and winter gas in the Pacific Northwest (especially this year what with our global cooling). Just take it for a run around the block, Ken, and get rid of the winter gas.[:D]

See you at the ABFM.



TR7 Spider - 1978 Spitfire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

Before I got too much into vapor lock, I'd check the simple stuff like the fuel filter. Last time mine was plugged (in a 7) it acted about like you describe. And as Clay says, "most fuel problems are electrical" so I wouldn't discount Mr Lucas off hand.


nick
'79 TR7

While I don't totally discount Mr. Lucas as a culprit, the most suspect electrical component would be the fuel pump. Having suffered repeated vapor lock in my old Datsun pickup, and having suffered electric fuel pump failure twice in my old Jeep, I'm pretty attuned to the symptoms. I left the tank nearly empty, so the simplest thing to try first is to fill it up with "summer gas" when I get back to Oregon in September. If that doesn't solve it, I'll look at the other possibilities mentioned. Thanks everyone.

Merv, I'm planning to camp Friday night at the ABFM; Dolly arrives Saturday and we'll be hotelling nearby Saturday & Sunday. Looking forward to a great weekend.

Ken
Anchorage, Alaska

1980 TR8, 1973 TR6, 1965 Volvo PV544, 1958 MGA, Jeep Cherokees