Guardian_Saint

This morning when I go to start my truck up but it take awhile for it to start so when it finally did I back up and when I hit the brake my RPM drop and was trying to die itself so what can cause this problem? So I didn't drive for the day, I have try to adjust the throttle and still happening. Another question a bad fuel pump will cause fuel pressure drop? thanks in advance.

thook

Considering you lost power when you hit the brake, it's more than likely vacuum related.

Schralper

Check the vacuum line to the brake booster.
Yes, a bad fuel pump lacks pressure.

Guardian_Saint

Ok guy's, just got back from work and made a closeup inspection and this have I notice, I check under the dash were the brake pump is sitting there so when I push the brake I can hear air is leaking from there so I do not know if this is normal or not can someone check for it for me? I can think that the air leak cause the truck to die down due to the air that flow to the brake system so maybe a bad gasket on the brake pump or the master brake? I'm thinking its the pump, but if brake master do not fuction well then you will have a loose brake pedal so it could be a bad gasket or the brake pump itself.

Yeah I might think my fuel pump is not pushing enough fuel when I first started it in the early morning, will take like 10 crank to get it started, but when its all warm or hot it will fire at the first crank. Thanks in advance.

dcg9381

The vac leak is not normal. You'll probably have to replace the brake booster.

You won't lose brake function, you'll lose the vacuum assist - it'll be harder to get the brakes to grab.

Guardian_Saint

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drew303

Master Brake cylinder bolts to the brake booster that bolts to the firewall..

if the booster has a leak you'll need to replace it. The engine will want to die if theres a vacum leak.

probably find a used one at a junkyard cheap.

Guardian_Saint

So just today I got the booster out and test it while it is out and it happen to grab fine. When I connect the vaccuum hose into the booster while it was out and compress it, there were no air leak, maybe due to the MC is bad so I tested the master brake and it only pop out in one line that might go to the front brake system so it doesn't seem that it is pushing the rear brake line so I think my master brake is doom.