Engine dies when braking in idle

[monkeypower]

I've been having a problem recently where my engine will die if I brake in idle. I can recover if I lightly throttle soon enough after braking, but when I'm coming to a stop sign or tight turn downhill, I don't usually have time, and it usually dies.

This doesn't happen if its in gear, or if I roll up to the stop sign slowly in 1st and then brake.

I've found a lot of people saying this could be related to a power assist brakes vacuum leak, but I don't have power assist brakes ('67). I am running a 1600 DP engine, though.

My guess would be something related to the idle speed adjustment, except it only happens when pressing the brakes (I can coast just fine).

Could it be the throttle positioner?

[busdaddy]

I suspect lean idle mixture or low float bowl level, the idle could be from crap in a jet or passage.

When you brake the fuel in the bowl heads to the front away from the idle circuit leaning it even more, if it's too lean already the engine quits.
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[Joey]

I had an engine with close to 1/4" of end play and whenever I came to a stop or idled down a steep hill the engine RPMs would drop and the engine would almost stall.
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Joey

‘60 Kombi - '74 Bus - '79 Panel - '65 Beetle

[monkeypower]

Ah, hadn't thought of the basic physics–I'll check that.

If all else fails, I'll check the end play (but I really hope it isn't that).

[lightice]

My 66 had a remote brake servo that I found under the passenger seat.
Had the same symptoms as yours.

[BarryL]

Do you have an idle cut-off solenoid? If so, try turning the little screw to override it and see if it still happens. I'm thinking your brake lights are robbing power and letting the plunger partially depress thus cutting off the idle circuit.

[Abscate]

A 1600 DP is expecting a 34 PICT 3 carb with all three timing control mechanisms on the distributor and a pull off on the throttle for control of revs during idle down.

If you have an aftermarket distributor and/or carb, its likely some of this stuff is missing.
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[monkeypower]

[mandraks]

does it make a difference if you are on the clutch or not? if you take your car out of gear, and take your foot of the clutch then the motor is turning your transmission. if your idle is low, or lean, that might be enough drag
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[lightice]

Glad you ruled out the brake servo, took me some time to actually find out what the heck was causing my bus to die.

[monkeypower]

Decided to drive around and try to reproduce, to see if I can rule anything out.

I tried braking pretty hard to let deceleration do its thing with the bowl level, but it turns out, this doesn't seem to be the problem (or at least not always). I was able to stamp decently hard, and never even get the red + green lights.

It seemed oddly correlated with braking the first time. If I went into idle, and then went on the brakes, I'd see the red + green lights. Then I'd take my foot off for a sec, and put it back on, braking just as hard as before, and no red/green.

And the last instance was when I was pulling into my garage, right at the very end (going 1mph), I switched it into neutral and went on the brakes to stop it, and almost stalled. So from what I can tell, it doesn't seem to be the bowl level, because I'd expect that to trigger mostly with the fast stops, and not with a super slow one.

[VolkzBitz]

Whilst driving, put the clutch in. Try this a couple of times, if it doesn't stall do the stop with brakes to make it stall. Let us know what happens.
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[LAGrunthaner]

I have the exact same problem on my 1600DP at every stop sign or stop light she dies too unless I rev her up fast enough. While driving she is fine too. I'll be interested to see your solution as I suspect my carburetor is running too rich or.........other.
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[mastorna]

I had this issue. Might be worth checking your mixture and cleaning your jets just to make sure as that solved my issue. Petty basic cause. Test out your idle when the engine is warm.
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[Busape]

Hi, I had a similar problem with my 64 in that it would stall every time I pulled up. Carby had loose bolt where it bolts onto the manifold and was sucking air. A simple fix. Maybe an air leak somewhere?

[BarryL]

[LAGrunthaner]

[60freak]

[monkeypower]

[LAGrunthaner]

Sorry again for hijacking this thread, 60freak is this what I need to remove? Is this the solenoid and do I need to disconnect the battery and clamp off the fuel line when I take it off and how should I clean it for proper movement? What does it look like inside of the solenoid and how does it work?