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123386
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Joined: November 13, 2007
Posts: 141
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 Posted: Fri Dec 12, 2014 4:50 pm Post subject: |
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The new master cylinder is working great but something is on my mind related to the two terminal brake light switch.
When the shop installed a new electronic fuel pump at the front of the car, to the right of the M/C, they wired the switch as follows:
But the diagram shows one terminal to the fuse box (or positive from the fuel pump) and the other terminal to the two brake lights.
Here is the fuel pump:
So please educate me, I guess the two terminals on the switch (one straight, one bent) are interchangeable? Both of my brake lights work... |
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sputnick60
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Joined: July 22, 2007
Posts: 3916
Location: In Molinya Orbit
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| Posted: Sat Dec 13, 2014 1:35 am Post subject: |
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The Pressure switch on the MC is a single pole single throw switch (SPST). Brake hydraulic pressure closes the contacts. It is fed from the fuse box only when the ignition is on. Your electrician cleverly used the brake light feed to power the fuel pump with also only requires power when the ignition is on.
You can swap the wires on the MC pressure switch either way but don't move the fuel pump to the same side as the brake lights. Otherwise you will only have power to the fuel pump when the brakes are on. You won't get far like that.
Nicholas
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123386
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Joined: November 13, 2007
Posts: 141
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| Posted: Sat Dec 13, 2014 7:39 am Post subject: |
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| Thanks Nicholas. So am I understanding you correctly that the shop wired this incorrect? The wire from the fuel pump should be connected by itself at the straight terminal on the switch and the two brake light wires connected together on the bent terminal on the switch? |
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123386
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Joined: November 13, 2007
Posts: 141
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| Posted: Sat Dec 13, 2014 9:29 am Post subject: |
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well, just moved the wires. found out the straight terminal on the switch is activated by the brake pedal, so now i have them crossed. time for round 2 this afternoon.  |
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123386
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Joined: November 13, 2007
Posts: 141
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| Posted: Sat Dec 13, 2014 6:39 pm Post subject: |
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I am going to route the pump to the fuse box like it should have been all along.
Last edited by 123386 on Sun Dec 14, 2014 8:49 am; edited 1 time in total |
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sputnick60
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Joined: July 22, 2007
Posts: 3916
Location: In Molinya Orbit
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| Posted: Sun Dec 14, 2014 4:17 am Post subject: |
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| Crooked wrote: |
| Thanks Nicholas. So am I understanding you correctly that the shop wired this incorrect? |
I meant they did a clever thing by using a double jumper to the pump. There is no extra power going through the switch and it is saves running an extra wire. A fuel pump doesn't suck much power so its all OK.
| Crooked wrote: |
| The wire from the fuel pump should be connected by itself at the straight terminal on the switch and the two brake light wires connected together on the bent terminal on the switch? |
Straight, bent don't matter so much its more that the wire from the fuse jumps to the fuel pump and the Brake lights are then on the opposite terminal.
I'm not clear what the problem was in the first place. You got it home right? Maybe I just confused you.
Nicholas
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'65 Porsche 356C Coupe...
2005 Mecedes Benz C180 Kompressor Estate
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123386
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Joined: November 13, 2007
Posts: 141
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| Posted: Sun Dec 14, 2014 9:08 am Post subject: |
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I appreciate your help Nicholas. It wasn't you who confused me, I am confusing myself.
Basically the car has been running like crap. Sputtering, hesitating, backfiring, more in 1st, 2nd and 3rd, more when cold. The shop feels the main issue is a clogged intake manifold, and that it isn't going to go away until that gets resolved. I am not so sure about that. The engine was rebuilt before it sat for 3 years.
I had a defective coil (it was leaking grease), and I was never happy with my H30/H31 carb, so I decided to go with a rebuilt 30 PICT-1 from Volkzbitz. Neither helped my issue, and now the car won't even start after sitting for an hour.
I adjusted the points (widened the gap). I also replaced some corroded spark plug wires. Checked the coil. Checked the spark plugs. Battery is fine. I have spark.
I adjusted the choke and verified that fuel is getting to the carb. But is there enough fuel getting there? Since they installed that new pump at the front, that sure is a long way for the fuel to have to travel. So I guess the next step is to check the psi at the pump and at the fuel line at the carb. I heard it should be 3-5 psi.
But I also want to get that fuel pump wire off the switch and route it to the fuel box instead. It's a shot in the dark, but easy.
Sorry if I confused you with my earlier posts. Cheers!
Jimmy |
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c21darrel
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Location: San Dimas
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123386
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Joined: November 13, 2007
Posts: 141
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| Posted: Fri Dec 19, 2014 3:24 pm Post subject: |
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| After verifying I had both spark and fuel, I adjusted the gap on the points and tightened down a loose intake manifold. Running like a dream now with my new 30 PICT-1 carb. Sooooo happy! |
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c21darrel
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