Engine Cutting Out At High Speed

[59bisquik]

Headed down to a car show this morning and the truck started to really cut out and jerk. It was on a slight downhill grade with a light load on the engine and cool weather. I was doing about 65mph so over 2500rpms. The truck started cutting out rapidly and losing power, like stuttering. It continued till I was down to about 45 and I pulled off. Letting off the gas and getting back on etc did nothing to help. As soon as I pulled over, she idled fine and would start right up if shut down. I checked the ignition wires and coil wires with no defects found. I pulled back onto the highway again and zipped through 1st and 2nd as fast as she would go, but as soon as I started pulling 3rd, it started again and I pulled off. It ran fine at lower speeds and go me to a gas station where I got a flatbed ride home. She was full of fuel with a new fuel tank/filter and rebuilt carb also. 

Any ideas? If its something easy, I would like to fix it. If it get to costing a bit of money like a new Pertronix unit or electric fuel pump etc, I am just gonna leave it broke for now. 

[greg g]

See if it occurs with the gas cap loosened.  Have you done the fuel flow quantity test outlined in the service manual?

[59bisquik]

Forgot to mention, I did pull the  gas cap at the first stop. Not a whole lot of pressure there. It did it as soon as she got back on the road again. 

I have not done any troubleshooting yet. I got her home and then went to the show as a spectator.

[DJ194950]

I agree with Greg and maybe take a look in the carb after removing the top for junk and/or and water which might block the high speed jet.

Is the voltage ok at higher rpms?  Coil giving up at higher rpms and under heavy load-I doubt this but--

Are point springs tight, points set right or it you already have the Pertronix ign. is the shaft so loose in the housing that it allows the gap to open to far for the pickup to work? Same for point setups. Pertronix setups are very forgiving on the clearance but cannot be too far off-if adjusted per instructions but are voltage sensitive beyond  limits.

Just some cheap checks??

DJ

[Merle Coggins]

It sound similar to when I goofed and didn’t get the spring attached properly on my points. I would experience points bounce at higher RPM’s, most noticeable in 4th gear. While that may not be your situation, I suspect something going on in your distributor. Possibly one of the small wires shorting out. Or maybe a condenser failing, coil failing, or maybe the spring broke on your points???

[59bisquik]

I will have to check the carb out. As for the distributor, it has a Pertronix kit in it.

[The Oil Soup]

The first thing I would check is the fuel filter. It could be partially blocked allowing some fuel through but not enough for high fuel consumption. Cheap and easy.

[Veemoney]

Fuel filter or pump. It doesn't take much restriction to cause a fuel starving problem like your describing. I run a 6v electric and had a similar issue. Replacing the filter fixed the problem.