NO brakes at idle

[zukinut]

So the other night while backing my trailer down a driveway my trucks brakes lost boost assist while the truck is at idle. They work great any other time (well other than the lockup issue) but at idle they act like the vaccum pump went bad. I have no idea what causes this but it is not a good. Any ideas for a remedy. Oh yea, the vaccum pump is only 500 miles old.

Will

 

[k_williams1982]

I'd check the hoses for any "pin-hole" leaks. I'd say a weak pump, but with only 500 miles on it, it should still be good.

 

[NJGearhead666]

put a vacume gauge on the truck and see what its pulling at idle just cause its only 500 miles old dosent mean its working properly.

 

[zukinut]

what should it be pulling

 

[EMD_DRIVER]

what should it be pulling

At least 18... Mine pulls 21, no problem...