hello i have a 73 corvette 5.7... i was driving and after about 5 miles it would drive then die, then start up then die then start up then die. what is going on? no leaks... everything looks okay? help.

 

Possible fuel filter plugged, that's where I'd look first. Should be one just after the fuel pump, and then one just where the fuel goes into the carb.

 

I changed the fuel filters and I don't think pump is bad

 

If the fuel system has not been modified and you have the original carb, (a Q-jet), it has the only fuel filter in the system. It is behind the large nut where the fuel line goes into the carb.
Check all your electrical connections at the distributor and coil. Also check the points if you have them.
Check the connections at the horn relay also.

Let us know what you find.

Fran

 

I think I'd look at the coil first, but I wouldn't rule out the fuel pump.

Does it start right up, or does it have to cool down a little first?

Does the car still have it's breaker point ignition, or has it been converted over to something like the Pertronix electric ignition? Normally when the aftermarket ignition systems fail, they quit altogether, but I have heard of them causing intermittent problems too.

 

Check the primary wire from the distributor to the coil. It moves every time the breaker plate moves.

 

I would start by replacing the little pleated paper filter that is in the inlet of the QuadraJet. Less than 5 bucks and available at any auto parts store. If the filter doesn't cure the problem stick a piece of 3/8" fuel hose onto the pump-to-carburetor fuel line and see if it delivers 1-1/2 pints of fuel in 30 seconds of cranking.

 

My HEI was causing backfiring/stalling.......a multimeter showed that the voltage going to the distributor is fluctuating from 2volts-13volts every few seconds. An old-fashioned voltmeter was not sensitive enough to show the rapid voltage fluctuation.

Not saying that's your problem, but check the voltage while cranking the engine and while the engine is running/revving just to be sure.

 

I had a similar problem with my 73 454. After 6 months of chasing this problem by replacing various parts I decided to replace the fuel filter sock in the tank. That is what finally fixed it.

At idle the tank filter let enough gas flow to the carb to fill the bowls and keep it running. That is why it never died while working on it, or testing it in the garage. Going for a short drive around the neighborhood would sometimes work also. But then I never gave it much gas, and I am thinking the fuel flow was enough to keep the bowls full.

However driving it on the hiway, it would go 5-10 miles and then just die. After several minutes of cranking it would refire, and I could slowly crawl back home.

The fuel filter sock was black when I took it out. The new one was white. I think the discoloration was due to all the varnish/gunk that accumulated over the past 42 years. Since I had the car the past 10 years I drive an average of 500 miles per year. That may have been enough time to add to this problem.

Summary: I replaced the filter and the problem was fixed. On the 73 you do not have to drop the tank. The fuel pickup unit access is on the bottom.

kdf

 

We all know what it takes to keep an engine running; fuel , air, compression, and spark at the right time. So first you need to determine what's not happening. If it's got a clogged fuel filter, bad fuel pump, or something else that restricts the flow of fuel to the carb, the car will act like Sam says. If when the car starts to die, you let off the gas and coast to the side, it would probably keep idling down the road at low speed and under light load. if it doesn't and just dies, kill the motor, open the hood, pop off the air filter and look down the carb as you move the accelerator linkage. If you don't see the accel pump nozzles squirting fuel, your bowls are empty and you have a fuel delivery problem, if they're squirting, you're getting gas and the problem is elsewhere.

The fuel filter sock was black when I took it out. The new one was white. I think the discoloration was due to all the varnish/gunk that accumulated over the past 42 years. Since I had the car the past 10 years I drive an average of 500 miles per year. That may have been enough time to add to this problem.

Summary: I replaced the filter and the problem was fixed. On the 73 you do not have to drop the tank. The fuel pickup unit access is on the bottom.

kdf[/QUOTE]

 

My guess ....JUST GUESS ....I d look at .

Either the Rochester carb inline filter ...quick cheap replacement .

Then .....if the points have been changed to HEI ...might change out module . Electronic HEI does crazy stuff sometimes.

If still has points and coil ......switch out coil.

Main coil wire ...good?

I wonder if a ground is failing because of heat .....bad connection though safety switch , key switch , grounds for engine ....heat opens poor connection.

Then I'd investigate the complete fuel system ...pump , carb overhaul? And tank sock.

 

Try driving with the gas cap loose. May be a vacuum sucking OLD soft lines closed. I had that happen once. Took forever to find the problem.

 

What octane are you running? My 78 would continuously stall at lights, etc. Started putting 85 in it, and problem went away,