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TR2/3/3A Hesitation on acceleration, wants to stall at corners

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peterriley

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Wonder if anyone can help with a problem that's been going on for years. It's a '61 TR 3a that is very hard to start when cold, perfect when warm, hesitates when you come back onto the gas after backing off, and worst of all tries to stall when you come to a slow corner or stop sign. You can (just) keep it going with accelerator and if it does stall out it will start right back up again. The thing is I have thought i've fixed it several times! The carbs have been professionally rebuilt and I've fitted a new coil. Each time the improvement has been dramatic only for the problem to reappear down the track. All ideas gratefully received!
 
Lots to consider here. Have carbs been tuned lately, leaks, diaphragms, oil in carbs proper. Choke? Hard start cold. Timing and dwell? Vacuum line to advance/retard. Fuel pump diaphragm, leaks? Might not see leak from outside, but can leak into oil. Fuel filter, and is tank vented or line crimped or leaking? Do you remember what you did to improve it before?
 
Peter - welcome to BCF.

I assume after the carburetor rebuild, the carbs were properly set up and adjusted, the ignition (distributor, timing, plugs, etc.) are set, and there are no vacuum leaks.

First thing I'd check would be fuel pump. I had a similar problem. If fuel pump is failing, or there's insufficient fuel flow, you'd have the symptoms you describe.

Just my two cents.
Tom M.
 
The fact that it is worse on shut throttle may point to air getting in through the wrong places, like throttle shafts, bad manifold or carb gaskets, etc. I would also look at gasoline levels in float bowls. I think John Durant has pointed out that, when the bowls are full (shut off by the needles) and you remove the pistons and chambers, the gas should be right at the top of the jets. The problems, as you apparently know, can be very vexing and arcane. I believe it was Charley Fitch who had a problem with a TR6 stumbling in left hand turns. He finally discovered that the float bowls were from a slightly different carb body than those on his engine and the angle of the bowls relative to the bodies was causing the problem. Look at the forks on the float levers to see if both prongs are at the same height.
Happy hunting,
Bob
 
I assume you have stock SUs and they are synchronized. The cold start is the Choke. Depending on the weather where you live, a tr3 choke is critical and very finicky until you get the choke dialed in so it functions as good on return as opening. Your problem is fixable, but it will take some steps.

steve
 
I had a similar problem for years with my 60. No so much around corners but any time I hit the brakes the car would try to die. Much worse when the engine was cold, better when warm.

In my case is was caused by my incompetent rebuild of the carbs many years ago. I won't bore you with the details (suffice to say JB Weld was involved), but the bottom line was that the "return" when I would take my foot off the accelerator was inconsistent. This was caused by excessive friction between the carb body and the butterfly.

I suspect that the flexing of the body when braking was pushing the linkage and having the same effect as if I were putting my foot under the accelerator pedal and lifting it up. If the carbs and linkage are correct, lifting up the accelerator pedal should have no effect.
 
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