vapor lock problem

[Rickety Rhino]

My 84 Tercel engine sometimes hesitates, sputters and dies on hot days, and I can't restart it for awhile. It can happen suddenly when I drive up a long canyon, or if it's been sitting on a hot day after being driven, and I start it again - then it happens within a few minutes. The temperature gauge shows just slightly above the middle when it happens, i.e. it doesn't indicate overheating. If I open the hood and let it cool off for 1/2 hr., it starts and runs OK.
I replaced the radiator with a new 1" thick one (couldn't find a double row radiator), and I wrapped heat insulating tape around the gas hoses near the fuel pump. Didn't seem to help. The float level in the carb is within spec, maybe a little on the high side. The radiator fan works. I use 87 octane fuel, with 10% ethanol added (can't avoid it in my area). Does anyone have suggestions on how to fix this?
Thanks!

[irowiki]

Maybe the fuel pump is going out.

Perhaps the carb is in need of a rebuild? Do you have a spare to try?

[larry mcgrath]

First off remove the heat insulating tape, thats making it worse. you need to wrap the fuel lines with alumnium foil shiney side out. to reflect the heat. Next check the fuel pump pressure the spec is in the FSM Larry

[Petros]

it the ethanol blend, works okay in EFI cars, but runs like crap in the older carb cars.

the exhaust manifold cooks the fuel pump and lines when not moving, you need to find a way to keep the air circulating under the hood when you are not moving.

usually the cool fuel coming from the tank when it is running will be good enough, and you have this problem when you stop for a short time and there is no air circulation. Opening the hood when you stop to get gas when it is hot usually helps, but perhaps slowly moving will also create the problem.

see if you can find ethanol free gas by looking it up on here:

http://www.buyrealgas.com/

Or here:

http://pure-gas.org/

[ARCHINSTL]

Thread from 6 years ago on this:
viewtopic.php?f=2&t=5615&p=41088
Since posting the above, I've wrapped the fuel lines with aluminum foil and, remembering a trick for the my old Ford V8 flattie days, put wooden clothespins on the fuel line in the engine bay to act as heat sinks.
Tom M.

[Petros]

how does wooden clothes pins act like a heat sink?

On the Tercel it seems to me we have to stop the heat from the exhaust manifold from getting to the fuel pump and fuel lines, adding surface area would allow it absorb more heat. best bet is a heat shield, light sheet metal, or foil perhaps.

I tried warping the lines with foil, it did not seem to help. I think a flat plate-like heat shield, like under the carb, would help.

[ARCHINSTL]

how does wooden clothes pins act like a heat sink?

I thought that anyone viewing the posted link would realize that the tinfoil and wooden clothespins on the metal fuel lines ploy was for the '88 Dodge/Mitsu p'up and not the Terc.
I've not had a single prob with the Terc on hot days, even the string of 100º+ days we had back in 2010; the p'up - see link.
Back to my preceding link - since installing the tinfoil and wooden clothespins - the old flathead V8 trick - I've not had vapor lock in the p'up...
However - - I still travel with a jug of water in the truck...
I suppose any type of item that would serve as a "fin" on the metal lines to dissipate heat would work - but I liked the solution of my youth...
Note that while the old Ford V8 flatties were the most notorious for this problem, they were certainly not the only '30's-'40's-'50s cars to suffer from that - and those cars ran on "real" gasoline.
Tom M.

[Petros]

So the clothes pins were just there to hold the foil closed around the fuel lines? that would act more like a heat shield, not a heat sink. Usually the term "heat sink" is used to describe a finned aluminum block that dissipates heat into the air, like a radiator but without any coolant. I could not see how wooden cloths pins would pull heat out and dissipate it.

Even a proper heat sink would not work under the hood, the heat source is also under the hood so all it would do is soak up more heat from the heated air over the exhaust manifold. for a heat sink to work it would have to be hotter than the surrounding air.

The only way to stop from overheating the fuel pump and fuel lines is to either create some way to circulate cool air to dissipate the heat from the exhaust manifold (a 12 volt cooling fan perhaps mounted near the fuel pump), or to contain the heat some how by wrapping the manifold with header insulation so not as much heat is released in the area around the fuel pump, fuel lines and carb.

[ARCHINSTL]

No, the clothespins were not placed to hold the foil closed - they are independent of the wrapped foil; I guess I did not make that clear.

However, all of this is moot, as I (and thousands of old-time flattie drivers) have simply been imagining it as a remedy.
That the pins and foil worked years ago - and currently on the p'up (as documented) - is just a figment of my imagination.
Perhaps I just dreamed it? Maybe I should try tobacco instead of Mary Jane?

Drat - another Urban Legend debunked, even without a Snopes link!

Say - did I ever tell you about the time back in 1958 when my GF and I were necking in a secluded spot when she heard a noise on the door, became frightened, and we peeled outa there. When we stopped, there was the bloody claw of the maniac who'd just escaped from the mental institution!
True!

Tom M.

[Petros]

Tom,

Sorry if I offended you, I am just thinking out loud. I am still not sure of the configuration of foil and clothes pins you describe, nor am I familiar with how the flattie fuel system was configured (I am not THAT old ). I have only seen the Ford flat head v-8 in hot rods. Clearly it worked for you, I am just trying to understand what action will cause it to work, and how that might help the Tercel in our current situation, with a vary different engine, a very different fuel mix, and yet apparently a similar problem.

Our issue I suspect is the with the current ethanol fuel blend, forced on us by our illustrious government looking out for the best interests of the corn farmers (and their lobbyists).

Short of paying extra for ethanol free gasoline (if you can find it), it seems to me we have to come up with a way of keep the fuel system cooler. A situation that the manufacturer did not anticipate 35 years ago.

[Jonymoto]

Just my 2c worth, I think Petros must be right about the ethanol causing the vapour lock. Here in Australia I only use 95 Octane fuel without ethanol and I've never had vapour lock problem in my T4. In the summer, our ambient temperature can get close to 120 deg F, even hotter in the outback.

[ARCHINSTL]

Look at my original link, blaming the blends of ethanol-added fuel we have.
viewtopic.php?f=2&t=5615&p=41088
Tom M.

[Petros]

there are a few independent gas stations that have ethanol free premium, but most have the blend. There are even fewer that all of their gasoline is ethanol free fuel, these are a few Union 76 stations (but not all of them), some of the CFN, and the independent Gull stations that also offer ethanol free fuel. airports and fueling docks also have it but it is very costly to get it there.

There is a small engine repair shop up the street from me that sells ethanol free "storage" fuel in sealed cans, gasoline that is supposed to be good for ten years if the can is unopened, but it costs $10 for one liter.

[Rickety Rhino]

Thanks for all the input. I used the links posted by Petros to find a gas station with ethanol free gas, and that helped a lot. It got me through the hottest part of the summer. Now that the weather is cooler, I can use the usual 10% ethanol gas without problems.

[Petros]

good to know! it appears to be the ethanol blend is the culprit as I suspected.