Manifold Vacuum pressure, How much???

[Phat_Bastard]

Does anyone know how much pressure i can expect from a intake vacuum port?

I have to find a vacuum switch to enable my remote start to disengage the starter after the vehicle has started. The alarm mfr reccommends using a vacuum switch for this proccess. I had been using a timer, but sometimes it is hard starting and it times out to early before it starts.

Let me know if anyone has had to do anything similar with their remote start.

 

[Alec]

My idle intake manifold vacuum pressure is usually around -18.

 

[Phat_Bastard]

ok thanks Alec, you wouldn't happen to know how much it is during cranking? What is the max it might be while cranking??

 

[Alec]

Well mine starts up on the first crank, so the gauge just goes from 0 to -18.

 

[Phat_Bastard]

Originally posted by Alec
Well mine starts up on the first crank, so the gauge just goes from 0 to -18.

Well normally mine does too. It is the occasional fast temperature drop overnight that kinda hangs the truck starting and it might take about 4 seconds to crank before starting.

Because I have a timer enabling the remote start to keep the starter engaged for 2.53 seconds, I run into a problem cause the starter will drop out before the engine has started.

Even after re-hitting the remote start, it won't start. It just needs to kick over for say maybe 4 seconds. So i need a way to drop out the starter being engaged after it starts.

A vacuum switch may be my solution but if it don't work I could damage the starter gears being that the starter might not drop out and the vehicle has actually started.

Unless someone can advise a wire that becomes positive(or changes state) after the vehicle has started, I have to look into the vacuum switch to cure my remote starter problem.

 

[V8BoatBuilder]

Some remote starters use a tap into the tachometer sensor to read RPMs. If you could wire in a trigger, or see if your starter has a lead that wasn't hooked up, it just might solve the problem.