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Brakes cause engine to bog down

1136 Views 5 Replies 3 Participants Last post by  John Gallagher
When I start my 83 Spider (L-Jet) from cold, the brake pedal is very hard and very high. If I pump the brakes, the pedal stays hard, but if I press it and hold it, it will sink and the engine will bog down.

Once I release the brake pedal, the idle returns to normal and the brakes work fine.

I am guessing I have a leaking or plugged vacuum line or connection somewhere, but what are the most likely suspects?
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I'd check the brake booster. It operates off engine vacuum. There is a one-way valve in the fitting screwed into the intake plenum then a hose that runs across the rear of the engine bay to the brake booster. Maybe the hose is leaking.

Link to Centerline's page showing booster, one-way valve and hose.
Similar to a problem I had. Take the one way valve out and clean it. Solved my problem. Good luck, hope you problem is as easy.
I will check the booster today and post the results. Thanks.
I pulled the hose, and unscrewed the valve. I was surprised to find that there was vacuum in the line even with the car not having run for a week. I cleaned the valve and blew it out with compressed air. After I reinstalled it, I fired up and found the pedal with the expected feel.

Good call, guys, Thanks.
Yeah! Congrats.
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