1979 International Ignition/Wiring Problems

[mbc18]

Hi everyone,

We recently picked up a 1979 International school bus (don't know the exact passenger cap. but I believe it's about 30') that has had some...issues with running smoothly. It was sold as a running vehicle and was running when I went to pick it up but was hooked up to an auxiliary tank and battery. We put in a new battery and reconnected the fuel line which was fine and then it died. According to the seller, it needed needed a ballast so we put one in and it was fine until it died again – this time on the side of an interstate highway. Now, it looks like there's no spark. Someone stopped to help us out and came to the conclusion that the person who was originally working on the bus wired it terribly, the ignition wiring was garbage (he had some choice words for it), and that we just needed to 'rewire it' and it would be fine. The problem is that while I have a decent grasp on working with old engines, I'm somewhat at a loss for how to tackle the wiring for this lovable old beast. I'm in town now eating but I can try to post photos when we get back to our spot on the side of the road. Does anyone have this model or had similar problems that have been figured out?

Basics: new spark plugs, new ignition set up, new filters, new transmission set up, brakes in good condition, and an old carb that'll be rebuilt when we're back home

[Robin97396]

It's really not possible to say what might be wring with your ignition system from the description. Luckily that should be something that any common mechanic can deal with.

Sorry to hear you're having so many problems with this bus.

[brokedown]

It takes 3 things to run a motor: Fuel, Fire, and Compression.

Presumably you didn't lose all your compression, so you can assume its one of the other things.

How do you know you aren't getting spark? You can test this pretty easily with a spark plug out, turn the engine over and look for the spark. If you don't have spark, there's a pretty short list of things that can cause it. If you do have spark, it may be an issue with ignition timing, but again that's unlikely to just happen all at once.

[Robin97396]

I think they're going to need to have someone straighten out the backyard wiring job. It shouldn't be that complicated. I don't know OPs skill level, so sorry if some of this is basic info.

Working on electrical issues that come from someone else, I was always taught to look for the black electrical tape. Most of the time that's where the bad connections are.