I just purchased a 66 step side with a 6 in it. It has been sitting for 3 years. I have replaced the gas tank and lines, carburetor, plugs, points and condensor, distributor cap and plug wires. It starts for 30 seconds and then cuts off. It acts like there is no spark. I would appreciate any help
Recent threads similar to this have focused more on running out of gas. Bad gas, crud in the tank, or an old filter. Since you've replaced all that, perhaps it could possibly be a pinhole leak in the fuel pump diaphram, or a non-vented gas cap was installed. The cap must be the vented type or the resulting vacuum in the tank with cut off the flow of fuel to the pump. Is it known if the truck ran okay when parked? If it's been sitting for a long time the lifters could be gummy or stuck providing inaccurate clearance, or the points or timing may be off enough to cause a problem. You might also check to make sure the exhaust isn't clogged with a frozen heat valve or a smashed tailpipe. An open vacuum port somewhere that got missed can cause a hard to diagnosis condition. If you can keep it running long enough to get a reading with a vacuum gauge, that might provide a wealth of information. I wouldn't think it's the coil, since they usually either work, or don't. If it is electrical, I'd check to make sure the ignition switch and starter terminals are tight, and the battery cables are securely tightened to the starter and engine block.
Thanks, I have been looking for a vacuum diagram to see just how the vacuum lines are supposed to be on this truck. The previous owner has really done some unconventional additions and changes to the truck. I appreciate the list to get me started.
It sounds like just a simple lack of fuel problem. Take some Carb Cleen and try spraying some down the Carb when it starts to die and see if that helps keep it running then you will know if it's a fuel problem or not. Coils can be create a problem but they usually have to get hot first. If the tank is not vented properly and you think it's creating a vacuum a quick way to check it would be to pull the gas cap off, start the engine and see if it will stay running. As far as a vacuum diagram go's their shouldn't be anything more than a ported vacuum line to the vacuum advance unless you have a automatic Trans. and power brakes then you will need manifold vacuum to the modulator valve on the Trans. and power brake booster. The PCV valve which is located somewhere on the valve cover also uses manifold vacuum. If you are able to get it running long enough to check it with a vacuum gauge the readings should be between 17-21 inches of vacuum smooth and steady. If the readings are erratic and low then you have a vacuum leak which could be anything from a bad line to a leaky valve. The best way to free up sticky or noisy lifters is to take some ATF and pour a little down the Carb with the throttle open enough to keep the engine running. this usually will free up stick lifters. If you add ATF to a full tank of gas this will help clean and lube the top end of your engine also. I hope this helps. ...Big Tim
I had the same prob. Ive got a th350 behind a 283. The rubber hose connecting the vacuum line from the motor to the vacuum on the tranny (pass side of tailshaft) came off. Thing would barely start and refused to idle... good luck. gt
