Power Brake Booster Check Valve

[darrin75]

1969 Dodge charger OK I just bought a 12 v electric pump to help out my drum brakes, works great, but my booster Only has 1 port to go to this 12v pump.  This pump should kick on and off depending on vacuum.  Now the guy i bought it off of said I need a check valve between the 12 v pump and the engine?  At this time my brakes completely re lie on this 12 v pump to work, because i have no vacuum coming from the intake for the booster, because i have no where to plug it in?  Any suggestions. T- fitting?

[darrin75]

bump

[Steve P.]

I'm just guessing here that you added the pump due to low vacuum from the motor. That being the case, (I guess), why would you want to try to use engine vacuum again?  I am not an expert on this and no I did not sleep at the Holiday Inn last night, but if your vacuum was so low that you felt the need for the vacuum pump how is routing back to the engine going to help other than long slow stops that the pump should handle??

The pump doesn't run all the time does it??

I am a manual brake kind of guy, so I am not sure what is exactly what. I would like to know all the ins and outs too....   

[darrin75]

no my motor does fine, i added the pump as to when I go slow and have low vaccum and hardly no brakes.  The engine does a fine job when running at higher rpm's, but when I am just pulling out or parking the car, the brakes stink, so I added the pump, so that when the engine drops the vacuum down the electrical pump starts and picks the vacuum up for the brakes to be good again.  So, really my question is I need a check valve in between the motor or intake and the electrical pump, and then put a tee in so I can run that back to the booster. the check valve i assume is what tells the pump to kick on if vacuum is too low.

[Steve P.]

the check valve i assume is what tells the pump to kick on if vacuum is too low.

NO... A CHECK VALVE is a ONE WAY valve. It will only allow air/fluid to travel in one direction.  It will need a special VAC. pressure switch to turn the pump on and off, UNLESS it is built into the pump.. 

Didn't your pump come with any directions?? ?? ?? ??

It makes no sense to me to have both manifold vacuum AND the vacuum pump. No switch came with the pump or was recommended for it??

[kab69440]

What makes no sense is that his engine pulls more vacuum at speed than at idle. Something is not right.

[darrin75]

well ,  i thought with a big cam thats the purpose of electric pump, bigger cams work I think with more rpm's resulting in more vaccum, idle produces low vaccum with big cam. Am I wrong here.

[kab69440]

Well, not being an engine builder myself, I don't rightly know about your cam situation.