86 Dodge 600 vapor lock

86 Dodge 600 ES,34K orig miles, 4 cylinder fuel-injected. Runs fine when ambient temp below 75, but will not start with ambient temp over 75. Turns over, but no gas.

Orig fuel lines replaced by rubber lines, more exposed than original lines.

known issue,way back,old stuff,LEARN THE NEW STUFF SUCH AS CAN SYSTEMS,And stop the dumb stuff.

You say it won’t start because of lack of fuel. OK, give it fuel. Use Starting Fluid (or, equivalent) sprayed into the black intake tube. Does it, now, start and run for a few seconds? If it does, then, the fuel system is at fault. If it still doesn’t run, at all, the ignition system (spark production) is suspect. What’s the result?


Unless you’re talking celsius, 75 degrees is not enough to cause vapor lock.

Thanks. As soon as we have another warm day here in upstate NY, I will try your suggestion.

Agreed. I called it vapor lock for lack of a better description to fit the symptoms. Someone suggested a bad temp sensor or mass air sensor could be signaling the injection system to lean out the mixture too much.

The voltage values of all the sensors can be checked with a high impedance digital multimeter. Walmart has Equus brand one for $25.
You could use one to see if the coolant temperature sensor, or the MAF (Mass Air Flow) sensor are contributing to the problem.

Have you tried obtaining the fault codes stored in its logic module by turning the ignition key on, off, on, off, and on again, and leave it in the on position all without engaging the starter. The Power loss light should flash eight times pause then flash eight more times, thats the start of the test, all flashes after that will be fault codes, the last code will be 55 which is end of fault codes. See if you can record the codes and post back with them.

You could also join the Allpar forum and go in the EEK section. I’m sure someone could help you there http://www.allpar.com/forums/
Good Luck

Thanks to all for your suggestions. I will try them. It’s also time find another car, for safe kid transport, but I might give this car to my mother-in-law, so she has wheels.