Brake booster shot? ...Or perhaps carb needs tuned?

raintheory

Hey guys.

Noticing an odd thing with the bay this past week:

When depressing the brake pedal, the RPMs go up a bit then go like they are about to even out (no problem that from what I've read). However, instead of evening out, the engine starts to die. I have to tap the gas in order to get it idling ok (using the heel of the foot that's continuing to hold the brake no less).

I can't find any vacuum leaks. Previously I had replaced all of the brake booster vacuum lines that I could find after the bus started dying immediately when depressing the brakes. This includes the hose to the carb, as well as from the metal line up into the brake booster. Worked great for maybe 2 months.

Is my brake booster shot? Is there something with the carb that could cause this? My uncle and I have been fighting that carb left and right, and it was doing better along with the brake booster until this started happening.

My next thought is to disconnect the brake booster completely from carb and plug the vacuum port on the carb. The bus was like this when I first got it so it isn't a big deal if that works. ...I have power brakes currently (just the idle issue), so I have doubts as to that being the issue, but who knows!

Just figured I'd ask here before trying much more. At least to get an idea on what to start with.

Thanks all! Smile

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1974 Tin-top Campmobile
1973 Adventurewagen [RIP]

Mountain Minstrel · Posted: Mon Oct 12, 2009 1:04 pm Post subject:

Plug off the line at the booster, not the carb. If the problem goes away, you know it is the booster. If the problem is still there, plug it at the carb. If the problem goes away, you know it is in the line. If it is still there, the problem is somewhere else. I will bet it is the booster, but you never know until you isolate it.
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raintheory · Posted: Mon Oct 12, 2009 1:16 pm Post subject:

On the booster itself? What do I do with the line from the carb up by the booster? Nothing?

EDIT: Duh, I think I see what yr saying, on the line not the brake booster itself... let me know if I'm wrong (learning).
_________________
1974 Tin-top Campmobile
1973 Adventurewagen [RIP]

raintheory · Posted: Mon Oct 12, 2009 1:52 pm Post subject:

UPDATE: Well, I guess the brake booster is shot... Plugged the line back to the carb up by the brake booster and it works fine.

...Though I( did notice a line up in FRONT of the booster that I had overlooked before (read: not replaced). Guess there could be a leak up in that one, looks like a pain to replace, but I may try at a later date.
_________________
1974 Tin-top Campmobile
1973 Adventurewagen [RIP]

fusername · Posted: Mon Oct 12, 2009 1:54 pm Post subject:

the front one is just a vent line, doesn't affect anything.
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busdaddy · Posted: Mon Oct 12, 2009 1:55 pm Post subject:

The line at the front is the atmosphere vent, it has no effect on engine vacuum, but if it's full of holes dirt, water and dust can enter your booster.
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raintheory · Posted: Mon Oct 12, 2009 2:23 pm Post subject:


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