Brake lag after starting

Post by **stone36** » 06 Apr 2011, 13:19

what's his theory on the fuse? Is that just a higher rated than the standard?

trstjohn · Post by **trstjohn** » 09 Apr 2011, 08:01

Apparently, that's his theory.

As expected the 25V gives the pump more power; however, the sound/surge of power makes me a little nervous.
Any thoughts on this sound?

Post by **jimmy57** » 09 Apr 2011, 09:56

The fuse is there to interrupt the power supply in case of shorted wiring or excessive current consumption by components on the circuit protected by the fuse. The fuse is nothing more than a selectively sized strip of wire made of a metal alloy with a lower melting temperature. When the current exceeds the fuse rating by a small amount the metal strip melts.
Did the pump fuse blow? If the pump fuse was the reason the pump stopped then the pump may be faulty. Unplugging the pump and using a jumper lead for ground and using an ammeter for the power supply connected to motor wire and the other end to power source and checking the amperage while pump runs is the way to see if the pump is blowing fuse.
Fuses do not increase voltage.
The sound in the video sounds normal to me for one of those pumps. The sound quality of youtube videos heard over laptop speakers isn't the best so it may be worse sounding in person.
I am assuming your mechanic replaced the fuse and the pump now works.

trstjohn · Post by **trstjohn** » 09 Apr 2011, 13:59

Yes, the fuse blew, and my mechanic said the pump needs to be replaced.

Jimmy, what's your thoughts on using this a long term remediation?

Post by **jimmy57** » 09 Apr 2011, 16:04

OK,
What I do know without having seen your XC90: The vacuum switches that switch the pump on and off have been failing. Many that fail switch the pump on and off every few seconds and the vacuum pump gets hot and blows the fuse.
If it were mine I would replace the vacuum switch and see if the problems stops there.

trstjohn · Post by **trstjohn** » 10 Apr 2011, 09:24

Can someone please post the instructions for replacing the vacuum pump?

trstjohn · Post by **trstjohn** » 12 Apr 2011, 06:16

I ordered the vacuum pump from ErieVovo yesterday. $85 w/ shipping not too bad.

Today while driving into work I got the following error codes:
P2178
P2180

My mechanic did mention that using the 25V could cause other issues-- or maybe it exposed other issues?
Any thoughts?

Post by **jimmy57** » 12 Apr 2011, 07:19

It is a 25 AMP fuse he used, not 25 volts.
The codes are for rich mixture off idle. Leakage between turbos and intake, intake leaks, MAF sensor, or faulty O2 sensor(s). are possibilities.
The air leakage you'd get from any of the vac pump plumbing would usually give you poor idle and lean codes at idle but it is possible. The leak on vac pump plumbing would give you a fairly easily heard hissing noise.
Leaks on the plumbing between turbos through hoses and intercooler and to the throttle is usually leakage only when under boost and results in the MAF sensor registering air mass that gives more injected fuel but the air is not there for combustion since it has escaped. O2 sensors report rich and ECM adjusts and reaches an adjustment percentage that triggers the code as it is out of normal range for the adjustment or possibly at the limit of the adjustment range.

trstjohn · Post by **trstjohn** » 12 Apr 2011, 20:11

Jimmy,
Thanks for clarifying the codes.

I just checked VADIS and didn't see any instructions for replacing the vacuum pump. Replacement seems fairy straightforward.

Has anyone replaced one of these before?

Post by **jimmy57** » 12 Apr 2011, 21:54

two bolts, a pry out plastic catch for the hose, and a two wire connector. I guess air cleaner fresh air hose removal for more room.