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RPMs rev up and down erratically when idling and low speed


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1981 Subaru GL Wagon

Its not just the gauge. I can hear it from outside the car around the engine. The RPM needle will shoot up quickly, then drop back down in erratic spurts, and the engine will sometimes not react quickly or lag when I change gears and give it gas. It will sputter and eventually get up to speed. The RPM spurts happen the most at idle speeds, but its beginning to happen in all gears and up to 50 mph. Could the distributor be the problem? Anyone had a similar issue?

 

I've also had a little trouble with the carburetor, there might be a leaky carb gasket. I've got to pump the gas 5-10 times before I start the car for it to idle without cutting out. Anyone had a similar issue?

Edited by Tonyperkis88
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My car does that when its beginning to warm up. It only does it at idle really, but it does hesitate off the line sometimes. Mine is fuel injected though no carbureted.. So I figured it was just halfway between warm and cold and didn't know whether to choke it or not....

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Many details are Missing,

 

such like Model \ Year / Engine... 

 

But this:

 

... had a little trouble with the carburetor, there might be a leaky carb gasket. I've got to pump the gas 5-10 times before I start the car for it to idle without cutting ...

 

Sounds like a Vacuum Leak.

 

Check for Vacuum Leaks around the Carburetor,

 

by spraying carb cleaner around it at idle speed...

 

Kind Regards.

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BumbleBeast, You're right, I left out a lot. 1981 GL Wagon EA82 Engine I think (or EA81?) and I did spray the carb with carb cleaner a month or two ago and it changed the idle speed indicating that there is a leak, but I'm not positive that the leak is what is specifically causing the erratic RPM behavior.

 

The carb issue was kind of an aside that maybe it might have something to do with the wonky RPMs.

 

I was told its probably the distributor by someone who doesnt have subaru specific experience. Just wanted to see if anyone had some insight into it.

 

thanks

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Not the distributor.  Spark will not increase/decrease idle that happens from air/fuel.

 

You need to take off the top of the carb and do the following.  it is not nessecary to remove carb base from the engine.

 

1. Remove bowl plugs and drain bowl....this will allow you to use a spray straw on a can of carb cleaner through the drain holes to spray out the jets.

 

2.  Remove emulsion tubes (brass screws under top) CAREFULLY with a good fitting screwdriver so they don't strip........a few have caps on then the tubes are underneath.....there are 4.....remove them and spray them out good with carb cleaner

 

3.  Remove the lock screws on the side that pin the air horns, replace the tiny o-ring in each and reinstall.

 

4.  Install new accelerator pump

 

5.  Tighten carb base after all that's done.

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