H
Howard of Florahome
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- Last seen
- Joined
- Nov 2, 2021
- Thunderbird Year
- 1957
Transmission "stutters" (shakes, slips, hesitates) when starting at low speed.
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Sorry. Automatic.Automatic or manual?
Interesting you had several caps that weren't venting. I thought all the suppliers had addressed that issue. It is very important. I've never had an issue using ethanol infused gas but have a station close by that has pure gasoline.I also have occasional hesitation/stuttering from the engine under hard acceleration from a complete stop. I’ve always referred to my issue generically as being from the “engine”, so perhaps you’re referencing something different when you specifically say it’s from the “transmission.” What I’m describing on mine doesn’t involve the transmission slipping, so we may well be talking about different things. If so, please disregard the rest of this.
In any event, while mine still has such problems occasionally, it has gotten much better as a result of four things:
1. I always start out driving in low to the extent I can while the car’s still warming up; and even after it’s fully warmed up, I start out in low from a complete stop if I’m stopped on a significant incline or in a situation where stalling out would be dangerous (busy intersection).
2. My mechanic fixed a fuel leak on the carburetor and did a tune-up.
3. I started using ethanol free gas.
4. I vented my gas cap by drilling a very small hole in it (taking it off of and away from the car to do so, obviously). Note: I bought several (4) gas caps that were billed as being vented. All four of them resulted in noticeable vacuum and/or pressure in the tank when removing them after driving even for a short time, and regardless of the ambient outdoor temperature. It is possible that all four were defective; it is also possible that I have some unknown underlying problem that is being compensated for by having drilled the cap.
As to the latter two: correlation isn’t causation and all that, so I cannot say with 100% certainty how much of the improvement came from switching to ethanol free and venting the gas cap. I can say that on a scale of 1-10 where 1 is “undriveable” and 10 is “drives like a brand new modern car: perfect with no hesitation at all ever,” steps 1 & 2 above took me from about a 3/4 to a 5/6 and steps 3 and 4 then took me from a 5/6 to about an 8. Again, though, I’m sure there were multiple confounding variables (weather, driving the car more/less, etc.), but even accounting for those, I’m convinced that switching to ethanol free and drilling the gas cap made a significant difference. Gonna get the carb completely rebuilt, which will hopefully get it up to a 10 on this issue.
(And if I’m off base here, apologies! Feel free to ignore or delete.)
Thanks for the feedback. I hadn’t considered vapor locking may be my problem because I have been running an elec fuel pump for some time. I’ll make a vent hole in my gas cap to see if that helps. Also my transmission seems to be slipping (stuttering) and there is a viberation that can be felt in the car. Yesterday I noticed a hesitation to engage when I placed it in reverse.Had the same stumbling at full throttle, turned out the replacement fuel pumps (3) were garbage.. I installed an electric fuel pump (kept the original for the vacuum wipers) and solved the problem. The electric fuel pump mounts on the side of the chassis and uses the two bolt holes where the clutch pedal mechanism goes. No more vapor lock. Also cut the gasket around the inside of the gas cap about 1/8” to allow venting.