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Yeah that's the plan if I can find a way to seal a 1/4" to a 3/8" hose without it leaking.
I suppose I could just squeeze it down with a hose clamp but IDK how well that's going to work.
 
Discussion starter · #25 ·
I went to the parts store this morning but that check valve part # 47170 is a tiny 1/4" where the rest of the hoses on the system are 3/8".
I'm not sure if the pump itself has an integrated check valve. This is it -- https://www.amazon.com/dp/B0049HEJFW

How hot should the vacuum pump be after it runs a while?
No that pump doesn't have an integral check valve
 
Discussion starter · #26 ·
*Edit: Sorry I misread where you suggested the location of the check valve. I'll give it a try.
What about my finger jammed in the hose, same condition?

Something I've read on this switch in particular is that the on/off tolerance is too close and/or nonexistent. You can't have an exact pressure setting, there must be a +/- tolerance similar to a thermostat.
a finger blocking as you described wont help, you need the check valve between the pump and the sensor switch.
 
Yup already order some check valves. Impossible to find a 3/8" locally, no one carries them.
I'll let you know how it goes, reverted it back to standard engine vacuum until Wednesday then I'll follow up.
 
Alright I have the check valves all in place.
1 after the pump, 1 after the pressure switch and 1 after the vacuum reservoir just before the brake booster.

The short cycling still occurs at the built-in check valve of the vacuum reservoir.
If I disconnect it from the check valve and put my pinky in the hose the pump stops.

If I reconnect and put my pink on the inlet of the canister (inlet going to the booster) it short cycles.
 
I removed the check valve from the canister and that stops the pump.
Now I resealed the brass inlet and tightened as tight as safely possible.

I feel like it's leaking at the rubber grommet that holds the check valve in.
When the sealant dries I'm going use some smoke to see if I can find the leak.

Thanks!
 
Alright the system is sealed and holds vacuum but the relay / pressure switch is still a little wonky. Here's a video.

If this is normal and the pump is okay receiving 100 on/off cycles then I'll let it go and relocate the relay so I don't have to hear it.

 
My pressure switch is dead so I upgraded that along with the relay. (video at the bottom and this should conclude the mod)

Here's an updated parts list which might help someone current day. (9/2022)
The wiring for the Hella Solid State relay differs slightly.
  1. Using a standard relay harness your fused\key on power 12v supply will go to pin 30.
  2. The output 12v load is pin 87. (this is the feed voltage to the pump)
  3. You will provide a constant ground to pin 85.
  4. Your trigger wire is a ground switched by the pressure switch to pin 86.
Standard Relay Harness
Standard Inline "Add a Fuse" w\30 amp fuse
Hose Clamps

Hella Solid State Relay (SUM-760155-1)

GM Power Brake Booster Pump (Part # 20804130)

Jegs Vacuum Canister (Part # 555-63010)

Summit Racing Vacuum Pump Switch (Part # 931774031)

3/8" One-Way Check Valves

5' of High Temperature Silicone Vacuum Hose

Here's an updated video:

Image
 
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