[64speed]

When I got the car it had a tr power on it and after about 50 miles of driving it left me stranded on the side of the highway. I figured it was heat soak because after a while it fired right back up and seemed to run fine so I never really worried about it again. I took the tri power off and am running an aluminum radiator and the temperature never goes above 190 but intermittently and I mean very rarely the car will stumble at speed. If I mat the accelerator and just 'power' through it it will eventually even out and start running right again but it does it frequently enough to where I am afraid it is gonna die on me at a red light. Ignition is pertronix in stock distributor with what I guess is stock coil. Stock gas tank that I dont really know anything about. I have a complete MSD ignition setup including the box, distributor, coil, wires, etc......but I cant help but think that its fuel related. Oh yeah it has a stock mechanical pump. Any ideas?

[STEELCITYFIREBIRD]

The best thing that could happen is for it to quit, then you will have a hard fault and not an intermittent.

Is it specific to a certain RPM range or any RPM?
Is it surging or cutting out?
Happy hunting!

[Blued and Painted]

WAG/ cracked spark plug insulator.

[Half-Inch Stud]

...about to cough-out a rod?

[64speed]

No nothing violent enough to cough up a rod. Its just cutting out like its starved for fuel. It dies then comes back then dies then comes back then keeps right on trucking. Only once has it died on me for any length of time and even then after 15 minutes it fired up and took off.

[DOC]

is there a vent on the gas tank? or vented cap? Maybe on of them is not working and creating a vacuum in the tank. as soon as it dies, it allows the pressure to normalize and allow fuel to move to the carb again....

[pfilean]

I want to follow this thread for ideas. Been having a similar problem with about the same equipped engine. Only thing I might add is that when it happens I see no change in tach reading which I take as evidence the Pertronix is still working. Yeah, could still be coil but I doubt it. I'm about to take out all the old rubber tubing (some 10 years old) in the fuel lines. At least that is a fairly inexpensive effort at solving the problem. Maybe getting some ethanol by mistake has eaten up the inner lining of the tubing.

[STEELCITYFIREBIRD]

So it does this at idle, cruise, or wot ......or some combo of some of these?

[gtofreek]

This kind of sounds like the type of issues we have with the fuel around here. It gets hot, and starts boiling when it enters the carb, then it makes the float bounce, and the fuel level gets too high. Then if you floor it, you use that extra fuel, and get more volume of fresh, cooler fuel in the carb to help out, until it gets hot again. Todays fuel with ethanol can boil at really low temps. I've even been having issues with my fuel injected car on long hauls. Are you living in hot country, or high elevation? The higher the elevation, the lower the temp the fuel boils at.

[64speed]

Temperature doesnt matter because it did it at 210 with the old radiator and it does it at 190 with the new radiator. Is the fuel system supposed to have a vented or nonvented cap because I see applications for both. I am about to the point of replacing the whole fuel and ignition system. I never liked this pertronix crap anyway

[gtofreek]

Engine temp has nothing to do with the fuel problem. I'm talking about ambient air temps. For an example, if the fuel boils at 100° f, and the outside air temp is 95° f, then after a little driving, the road heat, and engine heat raise the fuel to above the boiling point while in the fuel lines, but since it is under pressure, the fuel does not boil. Now, as soon as the fuel enters the carb, it is no longer under pressure, and it starts boiling.

An easy test is to drive it late at night, or better yet, early in the morning when it is cool out. If the problem is not there then, but is there during the warmer parts of the day, you know the fuel is boiling when it's warmer out. I've read that some of todays fuel can boil as low as 95° f. During the summer here, my fuel actually boils in my gas tank, and creates lots of pressure. My gas mileage drops about 3 MPG during the summers because of it. This all started last summer. Been this way for 2 years in a row, but was never like this before then.

[64speed]

I really don't think it's fuel boil. I already had a full MSD kit I was gonna run in the car so I just went ahead and bought a new tank,pump,and lines. I'm done hunting!!!!!

[Blued and Painted]

Originally Posted by 64speed

dies then comes back then keeps right on trucking.
If I mat the accelerator and just 'power' through it it will eventually even out and start running right again

Neither of these descriptions sounds like fuel starvation.
Is there any black smoke or foul exhaust smell?
Whats the plug gap and type?

[lust4speed]

I'm with Paul on fuel temp. Add in heating fuel up near any exhaust pipe. This is worse during slow speed running or idling since there is less air flow to divert heat away, and not much fuel is being used at idle so it stays longer in one place being exposed to the heat source.

[64speed]

Well I think I have eliminated spark from the equation because when it died this morning (75-80 Degrees out) I pulled over and poured fuel down the carb and it would fire right back up and then die. Thats not hot enough for fuel to be boiling and I was running on a major highway with traffic. Rather than "power thru it" I intentionally let it die to see if I had spark. I have like I said a complete ignition and fuel system for all intents and purposes ready to install I just dont want to end up chasing my tail. Any thoughts now? Also what is the proper method for the fuel tank....vented or non vented?

[gtofreek]

It definitely sounds like it's running out of gas. Have you checked the fuel filter. If it has an external one that you changed, maybe it has one in the inlet of the carb? I have had the sock in the fuel tank disintegrate and keep plugging up my fuel filter within a day after changing it. Also, if you have a mechanical fuel pump, I have seen the fuel pump eccentric not get installed correctly if someone changes the t-chain, and then it comes loose, and won't pump fuel except when it jams up momentarily sometimes.

[Tom Vaught]

Originally Posted by 64speed

Also what is the proper method for the fuel tank....vented or non vented?

ALL fuel tanks must be vented for the fuel system to work properly. Atmospheric pressure is what forces the fuel out of the tank when the fuel pump creates a vacuum (negative pressure) in the fuel line. Most performance vehicles need a 3/8" vent line, at least one, and more than one is better.

Tom V.

[64speed]

Just for the sake of simplicity I replaced the "non vented" gas cap with a brand new Stant Vented cap and the damn thing didnt even make it to the end of the road before stalling so there goes that theory. I guess I am just gonna replace the whole shooting match

[Tom Vaught]

Even your new tank system will need a proper vent.
http://www.tanksinc.com/index.cfm/pa...cat/cat160.htm

Tom V.

[61-63]

If you haven't changed your rubber fuel lines from the end of the metal line to the tank and on the other end from the end of the metal to the fuel pump, try changing them. A pin hole leak in one of those can cause the fuel pump to pull air on and off and cause what you are experiencing. I had a friend who had that problem drive him crazy and putting a new line from the tank to the end of the metal line finally fixed it for him.