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1976 AMC Sportabout -stalls

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David1972 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David1972 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 4:09pm
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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 4:40pm
Originally posted by David1972 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.
73 Gremlin 401/5-spd.
77 Matador 360/727.
80 Concord Limited 4dr. 258/904


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Post Options Post Options   Thanks (0) Thanks(0)   Quote MaxiBlue Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 5:32pm
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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2018 at 8:28am
Sounds like a classic case of vapor lock. If you have a metal fuel line from the carb to the fuel pump insulate it. A piece of rubber hose big enough to go around the line can be split and used for insulation. You can also cut the metal line about an inch from the carb and fuel pump and replace it with a rubber line. Fuel boils in the line, and the pump can't push vapor, only liquid. If you have the BBD two barrel carb it could be vapor locking inside the carb with ethanol gas, apparently. I've never had that issue myself, ran a 1983 J-10 with the BBD carb for a couple years in all sorts of weather with E-10 gas. Not that it couldn't happen, especially in hotter, drier weather like out west (I'm in central SC).
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David1972 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/21/2018 at 12:09pm
Well I have complete all the items mentioned (fuel, new ignition coil, ignition control module, and replaced the valve cover gasket)  still dies after about 3-4 min then will not start unless it cools down .. I purchased a carb rebuild kit which I can try next.. any other suggestions is appreciated.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David1972 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/21/2018 at 12:25pm
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!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote maximus7001 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 5:26am
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.


Edited by maximus7001 - Yesterday at 5:31am
1968 Javelin SST

1997 GMC Safari AWD

2002 Chevy Malibu

1997 Ford Contour

Winnipeg, home of the Jets.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Today at 7:10am
I'm still betting on vapor lock. I drove my 63 American for 6-8 years before it started vapor locking. That's when I discovered that some regions have specially formulated gas for pollution reasons. Drove it from GA up to the Dayton OH area for a car show around 93-95 (AMO meet at the time). Never vapor locked before, and I bought and drove it in southern Idaho (Mtn. Home AFB) in 84-87, so heat wasn't the issue. Didn't vapor lock until I bought gas in Ohio, then it started! I ended up cutting the steel fuel line from pump to carb and installing rubber -- problem solved. Car has some mods, I was more interested in driving it than keeping it 100% original as it was my second car (wife had a relatively new one that was family car on weekends) and I had to rely on it to got back and forth to work and on occasional trips if the wife wasn't going. She would drive the Rambler, but really didn't like to, and I preferred her not to have to anyway.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Today at 5:02pm
OK - now with the info that it dies only 3-4 minutes after starting.....we can pretty much rule out vapor lock - it just isn't running long enough.  On the other hand....if the exhaust system is still intact, and the catalyst is still in-place, 3-4 minutes of run time is just about exactly what it takes to make an engine shut off if the catalyst is plugged.  Crank the motor up cold, and see if there's any exhaust coming out of the tail pipe.  if the answer is no - or just a faint amount - there's your problem.
73 Gremlin 401/5-spd.
77 Matador 360/727.
80 Concord Limited 4dr. 258/904


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