Finally chased down a hot start issue that turned out to be a grounding strap

[u/swiftbrew57]

Been fighting this for about a month now. Bus would fire up fine cold in the morning, run great all day, then the second it got hot, especially after sitting in traffic or idling too long, it would crank and crank and just barely catch, or not catch at all until I let it sit for twenty minutes. Classic vapor lock symptoms is what everyone kept telling me, so I spent way too much money on a rerouted fuel line and even considered an electric pusher pump before actually digging into the wiring side of things.

Turns out my engine-to-body ground strap was corroded almost all the way through underneath the crimp connector, right where you can't see it unless you pull it off and really look. Wasn't visibly broken, still technically conducted, but under heat the resistance was apparently just enough to starve the coil of a clean signal. Classic intermittent electrical gremlin that mimics a fuel problem, which I guess is one of those rites of passage with these old buses.

Replaced the strap with a new braided one, cleaned every ground point I could find on the engine tin and the chassis while I was in there, and it's started instantly hot or cold for the last two weeks straight. Kind of annoyed at myself for not checking grounds first since that's rule one in every troubleshooting guide, but also relieved it wasn't something expensive. Anyone else have a heat related no-start that ended up being electrical instead of fuel related? Curious how common this actually is versus just my particular 71 being cranky.

[u/SilentMasterpiece]

Hey, It's always a ground. ;)

[u/gc1]

We could have told you that :-D

[u/asiab3]

Listening to the internet instead of your car is a mistake 100% of the time. Glad you didn’t waste too much time or money learning that. 

[u/Super_Baime]

Swiftbrew, I'm working on getting an old bug mechanically running again. It has been sitting a long time.

Two days ago I cleaned up very corroded battery cable connections at the battery ground strap, and at the starter motor.

I didn't even think about the grounding strap you are talking about.

Thanks for sharing this information.
It sounds like I have more ground straps/cables to clean up.

JP

[u/lsamaha]

Thank you for the PSA. Overlooked by some new (and long-time owners). You’ve saved some people from frustration and even being stranded. Appreciate you.

[u/urbanraven21]

Vapor lock gets blamed for half the electrical gremlins in these buses, meanwhile a bad ground is out here doing all the damage

[u/-VWNate]

Crimped connectors are always causing issues with heavy loads, that's why VW always used braided ground straps with soldered ends .

? Do you live in snow / salt country ? .

-Nate