Why does it buck and die?

[David K.]

[Monte M.]

Re: Why does it buck and die?

Dave,
It could be a number if things, but the fact that you say it feels like it is out of gas, it may be a vapor lock. Basically, the fuel line gets hot enough to boil the fuel.
My first step might be to remove the air cleaner. Drive the car and as soon as it happens, jump out and see if the carburetor is still spitting fuel out of the jets.

You can also get heater hose, slice it, cover the fuel lines and it will act like isolation. If in deed it does help, at least you know what it is. Solving it will be easy.
If it is not it, at least we have eliminated it.

Best of luck,

[Philip C.]

Re: Why does it buck and die?

Try a new ignition coil. Phil 8063

[Larry B.]

Re: Why does it buck and die?

When this happens pull over do not hit the starter just remove the air cleaner then work the throttle while looking down the carb you should is fuel coming out the accelerator pumps if you don't see fuel the bowls are dry then look for fuel delivery problem. Another thing that can cause the problem caused by heat is the condenser.

[Jack C.]

Re: Why does it buck and die?

Ballast resistor?

[David K.]

Re: Why does it buck and die?

I have tried to move fast enough to get the air cleaner off to check for fuel and at least it always has fuel when I hit the throttle to check. I am getting to think coil as well. I had never thought of the ballast resistor. I have really been looking at fuel issues all this time and it very well could be yet. I am going to try the electrical items next and if that doesn't work, it will be back to the fuel. The threads on all the fuel lines, fuel pump mount and tank cover are just about wore out, removing them so often.Laying in bed last night, the only thing that came to mind that hasn't been checked is electrical. I am almost afraid to drive it for fear of it letting me stranded. Thanks all for the responses!!!!

[David K.]

Re: Why does it buck and die?

Monte, if it is vapor locking and the heater hose bears this out. What is the cure to stop it from vapor locking?

[David K.]

It is not the coil.

Just came back (luckily as the way it was running) from a test drive wiht a new coil. It isn't that. Must be fuel. I drove the usual 10 mi. when it started to buck and die. Hmmmm

[Edward J.]

Re: It is not the coil.

Dave, have you checked the fuel pump push rod length? It will sometimes wear over the years. and you'll loose the ability to pump enough fuel.

[Timothy B.]

Re: It is not the coil.

David,

Get a test light and after it quits test for voltage at the coil + primary lead. If there is no voltage try both sides of the ballast. Seems to me like a electrical problem that when hot opens and causes the problem you describe. Could be the ignition switch or the firewall connector where the main harness plugs to the engine harness.

[Monte M.]

Re: It is not the coil.

Dave,

Lets just wait and see if it is vapor lock. It is very difficult to tell by looking. The reason I said take the air cleaner off before taking it out for a drive, the time and movement of taking the air cleaner off could easily drop the vapor lock.

The reason I threw vapor lock out there first is; it does not cost anything to test it. You can use a damp towel if you want. Just make sure it does not get caught up in anything.

If by chance it is vapor lock, which I really do not think it is, I would need to see some pictures of the engine to see if any steel lines are too close to a heat source.

Each time you try something it narrows it down a bit. We will figure it out.

Just to be clear, it has done this ever since you put it back together five years ago? Any other input would be a great help.

Monte

Sticky float / low fuel pressure

[Rob M.]

Re: It is not the coil.

David,

Not that I'm an expert (by any means), but I'm with Timothy. I would looking for electrical issues. Are the plug wires reproductions? Check the ballast resistor and main firewall connection?

If the ambient temp is 82, what is the coolant temp? When you get home, can you reproduce the symptoms in the garage?

It is a real bummer to have a great car that you're afraid to drive for fear of being stranded.

I'm sure with the collective knowledge of the TDB members, you'll get it licked.

[David K.]

Re: It is not the coil.

Edward,I have not checked the fuel pump length, it sure looks fine when it was out though with no discernible looking wear.


Timothy, very well could be an electrical problem as after all we haven't found it yet. There is about 3000 miles since it was all rebuilt with new wiring harness and ignition switch.

I really paid attention in the last drive. When it starts to buck, if I get off of the throttle, it will idle it appears for ever. Driving through town doesn't seem to make buck as it seems there is enough stop and go, to allow a fuel problem to not be a problem. Once there is enough heat after about 10 mi. a steady cruise will have it bucking about a mile out of town at a steady throttle.


Correct, 5yrs. ago, is when it was put back on the road. New everything in the engine, back to original specs. Zip supplied the fuel lines that replaced the original. Rebuild kit for the fuel pump from Paragon along with an original looking clone from Paragon. DeWitt new factory style radiator. The engine had been on an engine stand about 10yrs. before that. The last I remember driving the car was around 1990. The original engine had some wild cam in it and it ran terrible unless wide open. I intended to redo it all, but never new it would take this long to get it back together again. I never drove the car in the hot summer until I redid the car/engine.

Hope pictures and more info helps.

[David K.]

[David K.]

Re: It is not the coil.

One more thing which may be very important. At first I thought it was just a fluke. But I have ran AvGas 100 LL and even blended it will pump gas about 50/50 and never had a problem. I don't remember the temp. of the days I ran this fuel though, but this is what I use to store the car for the winter. Is the alcohol in pump gas doing this to me? Must I run AvGas or a blend of it in the summer. A little joy ride or a long distance ride without AvGas available can be a PIA along with the price of AvGas at $6.25 a gal. Surely others don't have to run AvGas.