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ea81 runs fine in morning, backfires, misses, sputters when time to go home


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Hi Folks,     I love my 1982 L series, Aussie drive,   Got it 2 years ago and almost no problems.   It started bogging down, missing, so i replaced plugs, wires, ran some seafoam, and that fixed it, however, things have taken a mysterious turn.

 

8:30 AM... starts fine... as long as i use some choke (manual) until warm, it runs ok (otherwise it spits fuel vapour out of the carb, and misses)

 

runs fine all the way to work, no problems at all.  I leave it all day, until:

 

5:00 PM, time to go home.  it starts rough, and misses on either 1 cylinder, or even two.  loud (and i mean LOUD) backfires, zero power, smells like petrol,   my work mates think my car is a wreck.  it's rough all the way home... turn it off, and its fine in the morning.    

 

key question, what the heck is going on???   why would 12 hours overnight be ok, but 8 hours in a parkinglot cause all hell to break loose?   is the car afraid of my wife?

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Take it to Performance Automotive ?

 

You might research DiscoPotato03 who used SUEC and was unable to run engine long enough afterwards and sounds like all the disolved gunks, went back to hard gunk as engine cooled, stuck valves in the wrong places, but yours runs OK in mornings ???

 

I had similar, did everything then cleaned out fuel ines frpm carb to inside fuel tank. THUNK crap hit floor of empty tank, never did it again :)

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yeah, its sort of in half sun/ full sun all day long.  certainly its a bit warmer after 8 hours in the sun (@5pm) than it would be after 15 hours in the shade/dark (@8am).   Same thing again after work ysday,  barely  made it home.   And fine again in the morning!  (well not golden - but fine)

 

my feeling is simlar to post above - some gunk or something in the lines or carbie.  hoping to use the time difference mystery to help diagnose.

 

plugs and wires both good quality I think.  (paid a bit more).

 

considered new coil, but if it runs fine sometimes, can't very well be the coil as I understand anyway.  or the points.  the 'spitting' fuel vapor out the carb when cold tells me perhaps carbie is getting old & gummed up.  btw this doesn't happen at 5pm - rather it just never even fires the missing cylinder(s) until i rev it right up and run it out.  and oh those backfires , !  

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coils can be intermtent they rearly just stop working also i dont know if the ea81 uses 12v at the coil or if it uses a resistor but that if it needs a resistor and has 12v it will act like that to i had that problem in my scout for a while till i figured it out and switched to a procomp ignition the coil would work great and then it would sputter and die let it cool and then would fire up and run good for a bit again and besides there cheap and easy to change

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  • 3 weeks later...

solved...    the morning / evening thing was a bit of red herring (i.e. something that seemed significant, that was really not).

 

Still wondering why that would occur.

 

anyways, I filed down the points, and re-set the gap, and this fixed all of the stuttering, backfiring, fuel smell, low power etc.     The thing runs great now, even better than when I bought it 2 years ago.  love that ea81 engine!

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Yep well done it doesnt pay to assume problem is always fuel,  as  ignition problems particularly  breaker - points,  HT leads  (spark plugs) can break down as vehicle warms up particularly, if cheap or old tired. Ignition coils can do intermittant things when tired / failing.   vacuum leaks  hoses / inlet manifold.also

 

The 1st thing I look at like you did is the breaker points when my Brumby / Brat starts running like a hairy dog - ignition timing and spark strength are affeced when

they become pitted.    its a good idea to a spare set  

 

ps another good thing to do 1st before anything else is replace spark plugs (as you did) and air filter ie part of the process of elimination.

Edited by subnz
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