Hello everyone. I have a '73 coupe that I am in the middle of restoring. While, actually, I was attempting to restore it, realized its ridiculously expensive, and now I just need to get it running properly in order to sell it. So here's my problem. I had gotten the car running just fine. I drove it around for a few weeks. Then, all of a sudden, it started kind of choking down (back firing, not wanting to go, possibly like it was struggling for gas) while I was driving down the road. I get the car home, and while it is parked in neutral, I can rev the crap out of it, peddle to the floor, and the engine runs prefect. I take it out on the road again, and its the same thing. Once it gets going, shortly after I get out of first but before I get into third, it starts struggling again. It shifts fine, so I don't think it is anything to do with the transmission, but I don't really know. Hence the reason why I am asking the forum for help. Someone had suggested to me that the fuel filter might be clogged, so I'm going to replace that today, but I do not understand why it would run fine in neutral if it was the fuel filter. I do have to admit though, it definitely seems like the engine is having a hard time getting gas. I just need to get this thing running properly so I can sell it. Please help. Thank you.

-Chris

 

When you are moving in gear you engine is under a load.
Problem could be plugs, wires, rotor, distributor cap, timing or fuel filter.
If it was the fuel pump it would have crapped out fast.

My guess it is an electrical problem, probably a bad plug that is miss-firing under a load.

Good luck,

Schoon

 

I believe you are having some fuel starvation problems or vapor lock. You should check your fuel pressure at or near the carb. If it reads less than 3 lbs. you probably have a bad pump, clogged or crimped fuel line or some debris in the tank. There is a fuel sock in the tank that may be the problem also. If your car has headers the heat from them can cause the fuel to percolate when under load causing your symptoms. The fuel pump also gets very hot too so sometimes it will cause the fuel to boil and you then have vapor lock when you drive the car but may run okay at idle. Some people run an electric pusher pump back by the tank and either completely do away with the mechanical pump or keep it and run both pumps. C3's have a very tight engine compartment that holds in a lot of heat so make sure your fuel lines are not close to the exhaust manifolds. Some people wrap the fuel lines with some type of thermo wrap.