Speed bumps or pot holes causes engine to quit?

[bfloyd]

My car has developed a new habit that has me stumped. Coming home from a car show last weekend, I ran into a pothole on the interstate and about 2 seconds later the engine just quit. I still had electrical power, but the engine just quit. I coasted over to the shoulder, put it in park, turned off the ignition and tried to start it. It fired right up, and I drove 30 miles the rest of the way home.

This morning I dropped my son off at scout camp and when I ran over a speed bump... same thing. Took a little longer this morning to get it restarted, but it finally did. I popped the engine cover and checked the bulkhead connections and verified that the coil wire was still hooked up. No issues there from what I could see.

I checked the inertia switch, and it was fine.

Any clues?

[Bitsyncmaster]

My guess would be the RPM relay unless you have my solid state one.

[Ron]

Start it up, shake and wiggle everything, esp battery ground, connectors, relays etc

[Jonathan]

First guess would be the inertia switch.

Second guess would be the electrical connections for the ignition switch.

[David T]

Jumper the fuel pump circuit going to the inertia switch. If the problem does not reoccur you might have a bad switch. If it does not have a white paint splotch on it you should replace it in any case and if it is on the Lambda counter it should be moved to the footwell wall.

[Gregadeth]

Could there also be a loose connection here:
resistor-original.jpg

[FABombjoy]

The 2 second delay would lead me down the fuel pump circuit first.

At cruise, a functioning fuel accumulator would probably provide just about that much reserve fuel & pressure before dropping below the threshold of functionality.

[bfloyd]

After cutting out on me again on the way home from a car show on Saturday, I've left the car parked in the garage since then.

Tonight I started it up and let it idle while I poked and prodded around in the relay compartment and the bulkhead connections. Got no response from wiggling everything in the fuse box and relay area, but when I started messing with the wiring harnesses at the bulkhead connectors, I hit something and the engine immediately died. Not sure which one it was, so I pulled all of them out, cleaned the pins and connectors with a wire toothbrush looking thing and put it all back together.

It fired right up so I drove it over to the local shopping center parking lot (after all the stores had closed) that has speed bumps everywhere and deliberately ran back and forth over the speed bumps trying to make it happen again.

I kept driving back and forth the length of the parking lot until a local cop pulled up behind me and flipped on his lights. I figured he was going to write me a ticket for driving on antique tags on a week night. He walked up from behind my car and approached the back of the drivers side door. I rolled down the window and he starts off with the usual, "Do you know why I pulled you over?"
Before I could say anything he says, "You know you've got to get it up to at least 88 miles per hour in the parking lot for anything to happen right?"

I didn't get a ticket, and it never cut out on me the whole time I drove it tonight.

When I got home I did notice that in the relay compartment the two tiny fuses on my new fan fail module from Dave M. (Bitsyncmater) look like they are almost melted. I tried to pull one out but they were too hot to touch. I'm still running the factory fans, so it looks like I need to upgrade to new fans sometime soon.

[bfloyd]

After cutting out on me again on the way home from a car show on Saturday, I've left the car parked in the garage since then.

Tonight I started it up and let it idle while I poked and prodded around in the relay compartment and the bulkhead connections. Got no response from wiggling everything in the fuse box and relay area, but when I started messing with the wiring harnesses at the bulkhead connectors, I hit something and the engine immediately died. Not sure which one it was, so I pulled all of them out, cleaned the pins and connectors with a wire toothbrush looking thing and put it all back together.

It fired right up so I drove it over to the local shopping center parking lot that has speed bumps everywhere and deliberately ran back and forth over the speed bumps trying to make it happen again.

I kept driving back and forth the length of the parking lot until a local cop pulled up behind me and flipped on his lights. I figured he was going to write me a ticket for driving on antique tags on a week night. He walked up from behind my car and approached the back of the drivers side door. I rolled down the window and he starts off with the usual, "Do you know why I pulled you over?"
Before I could say anything he says, "You know you've got to get it up to at least 88 miles per hour in the parking lot for anything to happen right?"

I didn't get a ticket, and it never cut out on me the whole time I drove it tonight.

[dn010]

Those bulkhead connectors were one of the biggest PITA things on my car that caused all sorts of problems from engine running to losing taillights unknowingly. I'd use a small dremel bit on the female connectors and a wire brush on the male ones. Reassembled with dielectric grease. It would work for a while and then I'd have problems again. If this happens to you, if you pry the female side inward where the split in the connector is, it will make better contact - I am guessing they get a little too widened and don't connect as well.

It was a good day when I was able to remove these connectors for my EFI conversion.