Testing Vacuum

[mgull]

i bought my truck about 2 months ago and have had nothing but problems from the brakes. i've had the high hard brake pedal that many complain about. i tried replacing the check valve, and i tried the test in the fsm regarding the brake booster. on top of that my rear brakes don't seem to work. they work well enough to stop rotation when on jack stands, but hard braking on ice (i have the abs fuse removed) won't lock up the rear wheels. i thought i had bad axle seals leaking into my drums but it turned out to be a bad wheel cylinder(pads and shoes now replaced). i'm supposed to get access to a vacuum tester tonight but i don't know how many inches of merc, or where to hook it up. anybody out there that can help? anything else i should be checking? also i have bled 2qts of new fluid thru it but i've never had any experience with abs systems before.

 

[nissanh]

Was it like that when you first bought it?
There is a non return valve between the brake booster (servo) and the engine. Some one might fixed it reverse?

 

[fourwd1]

You may have a problem with the LSPV, which varies pressure to the rear brakes depending on bed weight.
You could try disconnecting the rod at the axle and tying it up to the bed. This will give full pressure to the rear brakes. See if that makes a difference.

 

[Dous]

You may have a problem with the LSPV, which varies pressure to the rear brakes depending on bed weight.
You could try disconnecting the rod at the axle and tying it up to the bed. This will give full pressure to the rear brakes. See if that makes a difference.

The only 3rd gens with an LSPV, AFAIK are 2.7L 2wd's.

 

[mgull]

i will look into the LSPV. thanks.

 

[mgull]

problems started right away after i bought it. i tested my vacuum last night at 15" of merc. i don't believe the brake booster has been removed before but i am about to replace it.

 

[nevada]

problems started right away after i bought it. i tested my vacuum last night at 15" of merc. i don't believe the brake booster has been removed before but i am about to replace it.

15 is on the very bottom.

how many miles on the engine?

 

[mgull]

i can't find anything looking like an LSPV on my truck.

 

[mgull]

it has 155k miles. seems to run well enough, although my gas mileage is quite poor. i've looked for intake leaks and bad hoses but all seems well. it came with a cold air intake. is there any possibility that it could cause vac problems?

 

[mgull]

i also just read that elevation affects the reading. i live at 9500 feet.

 

[mgull]

i got my answer today with a compression test. cylinder 1-100 2-150 3-145 4-150 5-145 6-148.