I recently purchased a 1976 Sportabout and it ran ok and kept an idle but had been sitting for a long time prior to purchase.  I flushed the radiator (which was pretty clean), changed the water pump, radiator hoses, thermostat, fuel pump, new belts, and some carb hoses that were dry rotted, spark plugs, spark plug wires, valve cover gasket (was leaking) and grommets on the top and new pcv valve, and heat sensor by the thermostat.  My thought I was making it better and it should run like a top now... no so much :) ..now it runs for 5-6 min first start up then dies...afterwards has to cool a min and only runs 1-2 min on remaining start ups.. any clues as to what I need to check?  Please keep in I am not a mechanic just learning..

Thanks

David

I promise you it's a bad Prestolite ignition module. That is precisely what they do when they go bad: the start and run until the module gets hot, then they shut off dead as a doornail until the module cools again. 

I bought my 1977 Hornet from Craigslist. When I called the owner to ask if I could look at it, he told me it would only run for a few minutes before stalling and would not restart for several hours. I knew immediately it was likely the Prestolite module, so I bought a module before I even saw the car and brought it with me when I went to look at the car. I started it, and sure enough it stalled five minutes later. I plugged in the new module, started it up, and it kept running. I bought it and drove it two hours home with no problems. That module lasted several years.

Your module has gone bad.

David1972 wrote: Thanks I am grabbing a coil and will look for the ignition module -can hurt to have new parts in it

Just stick with the 1 fix at a time routine - throwing a whole bunch of parts at it at once may fix it - but then you won't know what it was that actually fixed the issue.  Gasoline is cheap and you need it anyway, so start there.

I do agree on the Prestolite issue - if it's barfed it's resin all over the inner fender, that's a sure sign it's on it's way out.

The other thing to check, even though this doesn't fall under the symptoms you are describing, is to check the vacuum advance on the distributor. The Prestolite setup is notorious for ruptured diaphragms in the distributor, pull the hose from the source and suck on it - if there's no resistance from the distributor, you'll need to replace that as well - but again, this has zero to do with your symptom, but will go a long way to make the car run better overall.

David1972 wrote: Well I have done all recommended -new coil, new control module and gas still does after it warms up and then won’t start easily from there till it cools down. I guess I can have the carb rebuilt may other ideas are appreciated

What is the ambient temperature when this is happening?  and does the stalling happen while you are driving down the road (at most any speed) or when you are stopped at a light? And I know this probably sounds crazy, but does it do it more during the daytime than at night?  Now that you've handled all of the obvious stuff, I still have a feeling you are also dealing with fuel percolation/vaporization.  If you put your hand around the metal fuel line (about where it goes over the valve cover) and it is almost (or is) too hot to touch, that's likely what is happening. The old-school temporary solution is wrapping the line with aluminum foil, and/or clipping a bunch of wooden clothes pins to it to act as a heat sink.  If the problem suddenly goes away - that's what is going on.

The YF carb on my gremlin had not been rebuilt, and had the original float needle valve in it.  It has a rubber tip.  What I was told by a local carb guy was that when you run ethanol with the old needle, the needle swells and sticks preventing the bowl from filling, or sometimes overfilling depending on where it sticks.  He told me that the carb is easy to rebuild (which it was), but he cautioned me to buy a new kit, and not an old NOS or ancient kit that you might find on ebay.  His reasoning was that these older kits will not come with a needle that has the newer rubber formulation that can handle ethanol.  So I bought a new kit and the parts counter (even though old cheap kits can be found on ebay), and I never had a problem again with a sticking needle.  Even still, the car hates ethanol.

My car would start, run out of fuel, sit a little while, run, run out of fuel again.  You couldn't predict from day to day if it would start at all, or if it did, it may overflow through the carb vent.  Once when it wasn't starting, I took the carb lid off and found the float bowl empty.  Between this and the time if overflowed, it was easy to narrow it to the needle.  

If you choose to rebuild this, there are videos on youtube that are great, and the exploded diagrams are usually pretty good.  Just make sure everything is blown through with cleaner and is clean, clean, clean.  It won't even take a half hour.

The vapor lock sounds promising I will try that and plan on rebuilding the carb anyway.  The car had been sitting mostly since 94 so I am sure it has some trash in the carb.  To answer the questions when I got the car someone had it in their back yard and worked on a few things but never took it past their neighborhood street.  I drove it around the block and planned on buying it for a parts car for a 77 hornet hatchback AMX I recently picked up but after seeing and driving I just hated to tear it apart and wanted to make it live again.  I brought it to my farm (well small ranch) and replaced the fuel pump that was leaking during purchase.  I then drove it around the farm and it seemed to do fine but got a little hot and during driving and checking things the hood folded (it was rusted at the two weak points where it fits over the struts) so I finally got it down and drove it to the shop and parked it.  during the work to bend the hood back and weld bracing on each spot under the hood to give it strength I went ahead and replace hoses, flushed it, water pump, etc mentioned above.  After replacing the hood and all the work I drove it out of the shop and parked it to check things out and it died.. I tried to start it but wouldn't start till it cooled off.. it has been doing that ever since.. start it runs for 3-4 min max and dies then wont start.. I have been replacing all that was mentioned hoping to resolve the issue.  I will try the vapor lock and see about adding a hose at the cab and many the other options and in the meantime get the carb rebuilt.

Thanks for all the great info!

How old is the fuel filter? Mine plugged completely in about 2000 miles with brown gunk and would do what you describe. It turned out to not be heat. It acted as if it got better after cooling but turned out to be time that made it better. What was happening is that it would restart after a while but not right away. The gunk was settling in the fuel filter bowl and would allow it to just barely start. Any driving at over 35 - 40 mph it would plug up the filter again and make the carb run out of gas.

This was 2000 miles on a new (rebuilt) fuel pump and filter. Car sat for maybe 9 years before I got it. On a 68 the filter is huge and is in a metal bowl on the bottom of the fuel pump but I can see this happening to a lesser filter much quicker after a car sat for a decade or 24 years like yours. The filter being before the pump on this car is what saved the new pump.

On a car where the filter is after the pump the pump may plug up first.

I have never used anything but pure gasoline in this car, no alcohol.

it's fine to shotgun parts at semi-random, if it ends up working. past some point you will ahve to diagnose it from first principles.

so you start it, it runs OK for 3, 4 minutes. is it really OK?

when i stalls, stop. engine not running, if you manually blip the throttle, does it squirt gas onto the venturi horn?

was the choke fully open? or closed?

get a spare spark plug. when it stalls after 3, 4 minutes, pull off a plug wire, put it on the spare plug, ground the plug body, crank the motor. do you see spark?

gasoline, air, spark, compression, cranking. you just have to work each of these out one by one. all gasoline engines are the same here, the details change and the detailed dfifferences are immaterial.

otherwise, you're gonna poke and prod and generate lots of confusing, contradictory sort-of-symptoms that won't necessarily reveal anytrhing.