This was it, the big weekend when my 7 year long restoration project was about to be painted. I got to the body shop around noon, and there was still a lot of prep work to be done. First things first though, could I get it started after it had been sitting for almost a year?
For the young uns here, the old trucks had 12V electrical systems but 24V starting systems. This required a lot of battery power, and a persnickety little gizmo called a Series Parallel Switch. The SPS, also known as the curse of starting systems, used two sources of 12 volts, put them in series to make 24 volts and, if they worked, went to the starter and turned the engine over. The old Cummins engines also had a starting aid called a “Compression Release Valve”. It was a little T- handle on the dash and when you pulled it out, it opened all of the exhaust valves, letting the engine crank over easily.
I couldn’t afford new batteries, so I scrounged up 2 good 12V batteries, hooked everything up, and gave it a try. Compression release handle out, key on, hit the starter button, and, click click click bzzzzzz. Put my tester on the batteries and they were ok but I hooked a battery charger up to it anyway. Waited a while. Tried again. Click click click click bzzzzz. Aaargh. It’s the SP switch. I’d gotten pretty good at fixing them so I took it off, took it apart and inside was a silver disk where the contact was made to turn 12 volts into 24. They would usually get a little fried from using weak batteries, so all you had to do was turn the disk a little bit, put it all back together and, viola, starter turned the engine over. It worked.
Another potential problem from sitting for so long was fuel bleed back. And sure enough, even though it was cranking over with the compression release disengaged, it wasn’t firing. Again, aaaargh… There was a bit of white smoke from the exhaust but it just didn’t have enough motion lotion to catch. And the batteries were dying. What to do, what to do.
I took an air line from the shop and put some pressure in one of the fuel tanks. Waited for the batteries to come up to snuff and tried again.
Success! It was running and I drove it into the shop for the last bit of sanding, masking and finally, paint. But that was going to have to wait until the next day.