michaeliss

And so it continues. 1967 327-300hp powerglide convertible. I rebuilt this entire car. Every nut and bolt last year was taken off and checked last summer. Debugged it last summer made some fixes last winter. Car always idled rough. I rebuilt the card and still not good. When I would stop at a red light anything was possible from smooth idle to rough having to put foot on gas peddle to keep running. I replaced the carb with a new 3810. Car idles a lot better and better takeoff. The problem was I thought that maybe the carb was causing the highway problem. When I drive on the highway but not all the time, the car just cuts in and out or just dies. No backfire or popping. The car just dies I just coast, put the car in neutral , restart the car while going a long. The car starts right up in a second, I’m coasting about fifty and put back in drive and go along till it cuts out again. The engine was rebuilt, balanced, blueprinted and ported. A hotter cam was installed and 2.02 valves similar to 350hp engine. Original intake and exhaust manifolds and two inch exhaust, for stock appearance. I have an after market coil, Flame Thrower I think. Accel points, I set the dwell to correct setting, Accel cap and new correct looking plug wires. Rebuilt fuel pump, new fuel line and tank. The new resister is in place before coil. It appears that when I go up even a slight incline maybe it does it more often. It seems that when I drive to a show its fine and when I return a few hours latter it does cut out. It might not do it every time I drive on highway. The faster I go the more chance it happens. 75-80 mph it will happen. Do I look for electrical or fuel. This car runs fantastic now around town its great. Good power, great idle and on the highway if it is not cutting out, this car just goes. I slight touch of the gas peddle and car responds.

Allcoupedup

I'll throw out two guesses:

1) Vacuum in gas tank. Do you have a vented cap?
2) Clogged up gas guage sender sock or clogged fuel filter.

I lean towards #1 because the symptoms are more pronounced when you're consuming more fuel.

Brian

hope2

suggestion, run jumper wire from positive on battery to positive on coil, this will eliminate loose connection for the most part.
or, hook up a volt meter to the positive on coil and watch when it cuts out.
you say you rebuilt whole car, guessing fuel system is clean.

JohnZ

When the engine cuts out, do you lose all electrical power at the same time (radio, etc.)?

michaeliss

Radio still plays, and car starts right back up in a single revolution. If the car was running lean it would pop or something I think. If I slow down to say 60 - 65 it does not cut out. RPM 3000 at 70mph. I did not rebuild the distributor, it was nice and steady. Volt gauge stays right on zero unless I stop with heat fan and headlights, then it goes a little to negitive.
The new carb did make a difference. The secondaries open smooth and the car goes quick.
If the Carb starved for fuel at speed would not the car run too lean and pop. It sometimes cuts out with my foot on the gas pedal and the tach goes down and then come back for a second or two then cut out, come back and die so I start it again and slow down to say 60mph and it runs great. Flick the gas pedal while doing 60-65mph and the car leaps forward with a purpose.

RickSnow

I had this exact same problem with my 67. After replacing many other parts without success, I replaced the Ignition Switch and the problem went away. Good luck with your quest.

DSR

I had the same problem with an AMX I used to have. It turned out to be the plug where the wiring harnass goes through the firewall, One side of the plug would not lock on the plastic locking clip part of the plug, it looked like it was locked, but would pull out slightly on one side at higher speeds, the motor would quit, I would coast to a near stop and it would restart every time. Once I repaired the plug locking clip I never had this problem again. Dave

Shurshot

Way back in the day I had similar problems because of a loose connection at the resistor block. Never could find the problem until I lost some money doing something on the street........ then I did not stop until I found the problem.

Never did get a second shot though

Doug

macdarren

I had the same issue in my 65, the firewall connector would come a bit loose. A nylon tie-strap fixed the problem but it was hard to find...my big clue was it would sometimes happen as car flexed say going up a driveway ramp. But it was really annoying when it happend just driving along and suddenly I was coasting.

DansYellow66

From your description of how abruptly it cuts out and then back in, it definately sounds electrical. Once I failed to connect the TI distributor connection plug solidly to my firewall harness and it started cutting out and did so more rapidly as the connection got worse, but even then it never cut completely out as you describe. So it sounds like you have some component shutting completely down like the coil, condensor, broken coil to distributor lead, broken ground wire in the distributor, etc. Bulkhead and ignition switch sound like good suggestions too.

yleefox

Pontiac once. We would be driving along and all would be fine and then suddenly, it would quit. It took me a couple of months to find out what the problem was. Initially, it would start again immediately, but over the course of the weeks that followed, it would take longer and longer to relight. I replaced most of the ignition system, pulled my hair out looking for shorts or loose connections. Replace the fuel pump, rebuilt the carb, replaced the fuel filters, and cussed a lot. Finally found the culprit. The sock on the end of the fuel pickup, inside the tank. Crud would be sucked onto the sock, until it blocked the flow enough to shut down the engine. Then without an suction, it would float loose of the sock and the engine would once again start.

BTW, the car would run fine for quite a while, accelarating fine, idling fine, and then, boom, it would just quit.

Drove that car for several more year and never had the problem again.
Yleefox

Procrastination Racing

I had a similar problem in a Chevy van long ago.

The fuel line had an inline filter, connected with the two short pieces of rubber. The one between the filter and the carb apparently had a chunk of hose break off inside and flow into the carb and sit under the needle valve seat. As the gas flow increased, the chunk of rubber would flow up and restrict the flow until the engine died.

Then with no flow, it would settle on the bottom of the passage and the engine would restart. This was about 45-50 mph for me.

I discovered it when rebuilding the carb and removing the seat.

I would also look closely at that rebuilt fuel pump. It may not be supplying enough fuel.