Wiped cam lobe mechanical fuel pump

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,594
use a DVM to verify which one is common with 2 when you apply pressure
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,453
I can't figure out which one is the common. #2 is NC and it says the other two are no. Can you tell which one is the common?
1 &2 should be normally closed at rest, 1&3 will be normally open at rest.

hook wire from starter to 1 , supply from ignition hot to 3 , wire to coil to 2. will will supply 2 when cranking , 3 will supply 2 when ignition is on

Of course test this out on the bench Ohm meter plus compressed air cycle the switch) because my advice might be worth what you paid for it... but I think its right
 

boarnold

Cadet
Joined
Jul 19, 2023
Messages
24
I ended up pumping out the oil. Lots of shiny sparkles. I'm going to run for a bit then change oil again.
 

boarnold

Cadet
Joined
Jul 19, 2023
Messages
24
My fuel pump is now pumping if the engine quits. Even after oil pressure has dropped. I'm suspecting a faulty switch. One of the terminals wobbles. But I want to double check my wiring. I
The terminals are not labeled on the switch. I do have a diagram of the switch terminals. But I don't know which one is the common. How would someone figure that out?
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,453
My fuel pump is now pumping if the engine quits. Even after oil pressure has dropped. I'm suspecting a faulty switch. One of the terminals wobbles. But I want to double check my wiring. I
The terminals are not labeled on the switch. I do have a diagram of the switch terminals. But I don't know which one is the common. How would someone figure that out?
test with an ohm meter across the terminals. if they are not marked you may be on the wrong terminals, maybe metal from oil passage got pushed into switch?

You can hook switch to compressed air to get it to cycle
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,371
It would be strange if the terminals weren't marked... Guessing it should test like this:
1. Find the 2 terminals with continuity. Those are your FP output and your cranking power.
2. The other is to switched power. It won't have continuity to either of the other 2
3. Pressurize switch. Switched power now will have continuity with FP output.
 
Top