We start it up it sucks the brake pedal to the floor?

HONDARAIL

MEMBER
1995 FORD EXPLORER
6 CYL
4WD
AUTOMATIC
100,000 MILES

We recently purchased a 95 ford exploder for our daughter. It runs great. The only problem is when we start it up it sucks the brake pedal to the floor. When we remove the oil cap you can feel the vacuum, instead of blow by. What could be causing the excess vacuum? There is no trouble codes when we hook up the obd, and no troubleshooting section in the manual regarding too much vacuum.
Thanks

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

It sounds like you might have an issue with the brake booster.
The check valve on the booster can be faulty and causing the pedal to sink.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

First check all the hoses and connections to the booster.
Make sure the fluid is at correct level.
Remove the vacuum hose from the booster. You should have manifold vacuum at the check valve.
Operate engine a minimum of 10 seconds at fast idle. Stop engine, and let vehicle stand for 10 minutes. Then, apply brake pedal with approximately 89 N (20 lbs) of force. Brake pedal feel should be the same as that noted with engine operating. If brake pedal feels hard (no power assist), replace check valve and retest

I have attached diagrams for your reference.

Please let me know of any questions.

Thank you.

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