72 240Z drop in rpm to zero while cruising on interstate

[mynewzx]

i was driving down the interstate doing 65mph when my rpms dropped from 3200 to zero and the car's engine just died out on me. i tried to restart with the choke and got nothing. messed around with the dual carbs tried again and it almost started but the rpms went way up on me to the 3000 range then i got a loud backfire out of the exhaust like a .45 cal hand gun. tried messing with the carbs a little more by hand adjusting them, didnt have a screwdriver, and the same happened again got the loud backfire and could never get the car started. i walked to the nearest gas station bought extra gas and still i couldnt get the car started, had it towed to the house and its sitting in the garage currently.

info on my car is a 72 240Z automatic transmission, has a new distributor cap, new plugs and wires,. newer battery and radiator. the carbs were recently rebuilt but where never really synchronized. but despite that the car still ran. just 3 weeks ago i drove it 160 miles on a trip with no problems. battery is good i can turn the lights on.

the car is all stock with no mods. transmission fluid is clean and the oil was recently changed as well. i do get a spark , i took the air box off and noticed the air filter was filthy but that cant be the problem, also i cleaned up the air box itself since it was filthy. also there is a hole in the exhaust but that wasnt a problem for me when i took that long trip.

im not too familiar with the 240Z as i have only had this car for about a month. i never had this problem with my 91 300ZX

[EScanlon]

You mention you DO get a spark. When? When you're cranking the engine to try to start it, or with the key in the ON position (engine isn't running obviously)?

Just as a WAG, check the wiring to the Ignition Resistor. If that fried on you, then you'd have spark while cranking, but not when the key is in the RUN position.

Also check the points, if it's a properly stock AT, it should have dual points.

FWIW

E

[mynewzx]

its spark when trying to crank the engine

[d240zx2]

I had a similar situation about two years ago. Cruising on I-10, the car hiccupped and quit. Tach went to ZERO, engine died.

I found a connector to the ballast resistor had come loose. Reconnected and off we go!

[beandip]

You didn't mention the obvious , did you check the fuel filters to see if it is full or not? Are you running a mechanical and electric pump. Electrical only or What. Have you checked for gas flow?

[sawdust2005]

I'm having the same problem with my 70. When cranking the engine runs. It stops as soon as the starter stops. I can't restart it again for about 10 minutes after the first try. I cleaned the fuel filters, the electric fuel pump works, there is power at the resister when the switch is on. I have a recently rebuilt stock distributor, an altimator with a solid state voltage regulator and a battery that is less than a year old. Now what?

[Gary in NJ]

I'm having the same problem with my 70. When cranking the engine runs. It stops as soon as the starter stops. I can't restart it again for about 10 minutes after the first try. I cleaned the fuel filters, the electric fuel pump works, there is power at the resister when the switch is on. I have a recently rebuilt stock distributor, an altimator with a solid state voltage regulator and a battery that is less than a year old. Now what?

Sounds like the ballast resistor.

[mynewzx]

yep one of the connectors on my Ballast resistor was loose and fell right off when i touched.

i havent tried cranking the car since though, because i have some other things i need to put back on it. but as for right now im trying to get my 300ZX ready for Branson Z fest trip on thursday. i'll mess more with the 240 when i get back home.