Dan Michal

I'm posting here because I'm still new to the forum. I have an '83 gsl with 39k original miles. It is my 4th Rx over the years so I'm familiar with them. The brief history is that I bought it from a guy that bought it in an estate sale. It has evidence of being well cared for and is factory original on everything I see (that's one of the main reasons I bought it). I don't know how long it may have "sat up" but I belive it was garaged for most of the time. A relative of his supposedly "rebuilt the carb", but the air pump belt was off and various hoses were plugged. It runs good above 3000 rpm (I drove it 5 hours down the interstate getting it home). BUT, it will not idle, and bucks and surges at low rpms. I have since removed the carb and replaced the shutter/coasting valve, and reinstalled carefully. (I even got the special offset 12mm wrench made for the carb nuts, which was suggested on a link on this forum - VERY helpful!). I hooked up the air pump again and reattached the plugged hoses and replaced a few vacuum lines (looking for leaks that would cause idle problems). I've tinkered with air adjust screw. I've attempted to check and adjust timing (which was hard since it won't idle down without stalling).
Still no idle and runs lousy at low rpms. Any helpful ideas???
Could the low speed circuits in the carb be screwed up? (I really don't want to take everything off again or attempt a carb rebuild!). THANKS for any help!:

Kentetsu

Yeah, you could be looking at a need for a full rebuild. Check out www.sterlingmetalworks.com for great info on these carbs and some rebuild advice.





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mar3

iTrader: (8)

Miles don't matter to a carburetor. If it's been sitting and it had ANY gas in it at all, you've got varnish and in places you can't just clean with Gumout or Seafoam. If it sat dry, then there maybe insect debris in there and that's clogging internal passages. Not idling below 3000 and bucking and surging tells me leaned out engine. You've got vacuum leaks somewhere. Time for the propane bottle.

Mario III

1981GSL

iTrader: (3)

Would the air pump cause any of the problems? also, if the lines were plugged, it could be that they tried de-smogging it and botched it somewhere along the line. Sorry I don't know much about these engines, but hopefully you get it fixed!

Dan Michal

Hey guys, thanks for the reply posts. Mario III, can you elaborate on the "time for the propane bottle"? I'm assuming you might mean a method to help find vacuum leaks?.... Do you let the porpane blow out running engine and listen for changes? (I've heard of that with other stuff like starting fluid but it sounded dangerous, and I can't get the engine to stay running at low enough rpms, so it takes an assistant to keep goosing the gas and/or partially keeping the choke pulled...)
I've been sytematically replacing hoses but haven't got all of them done yet. And I did not replace or install a gasket under the plastic heat shield / thottle body piece (at joint with intake manifold) but I made sure it was clean and seated properly, nice and tight. Any other solenoids or valves that are known to cause these problems other than the coasting/shutter valve?
Thank you for your opinions.

mar3

iTrader: (8)

The propane gets inhaled at the vacuum leak and ignites easily in the chambers so the idle goes up. You could use Gumout Carb Cleaner also. Same effect. Idle goes up, you found the leak.

Dan Michal

Yes, idle goes up slightly (gets smoother) when I put propane bottle near open carb. Since then, I replaced all vaccum hoses and I think I checked everything to eliminate all possible vaccum leaks (a pretty tedious process but I labeled everything one-by-one with tape and went thru it). Dropped fuel tank and checked for debris and gunk. It was pretty clean. (And evidence of someone doing it in the past). Found aftermarket electric fuel pump. Tested for pressure and volume. It us putting out a solid 6 psi but factory book says it should be 3.55 (4) psi.
QUESTION: Could the extra pressure, even though it has return line to tank, cause problems for the sensitive carb at low rpms, maybe unbalancing the float bowls or something?
If so, can you suggest a reasonable cost source for OEM fuel pump, or aftermarket with right output?

Kentetsu

Yes, that could cause issues (fuel pressure). Go to SummitRacing.com and grab a Holley fuel pressure regulator (the low pressure model) and you should be good...


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