I have a 1985 GS with 50,000 miles on it. I recently replaced the fuel pump and fuel filter and rebuilt the carb. The car runs and accelerates well, but feels like it is missing or chugging at cruise. It is more pronounced at lower RPM's. I posted the same problem a couple of months back, and a couple of guys reconmended that I check to make sure that I had reinstalled all the jets in the right positions, while rebuilding the carb. I have just finished doing that, and could find nothing wrong with the carb. I took it for a drive and the problem still persists.
Any other ideas?

I have also checked the timing, vac advance and replaced plugs, wires etc...

 

Run it at higher RPMs! :p (What gear/speed are you cruising at?) Otherwise, make sure that the rats nest is reconnected properly, assuming you still have it.

 

Poor running at light throttle/cruise, eh?

Could be a small vaccuum leak. I've had a few over the years that exhibited that way. Have you checked for spark on the trailing ignition? Losing the trailing may also result in slightly rougher running at part throttle/cruise.

 

Thanks for your replies.
The problem seems to be most pronounced at about 3000 rpm. Also it doesnt seem to happen when the engine has no load on it - I can run it in the garrage and it sounds fine.
I also noticed that the idle is rougher since I worked on the carb last. All the hoses seem to be tight and ok, but I will checck again.
Lagging timing was good so I assume it is firig ok.

Dumb question - what is the rats nest. I have read a lot about it on the forum. How do I check it?

Bob

 

Take a look in the FAQ section, there are instructions on how to remove it which will help you understand what it is. Basically, it is the entire emmisions control assembly including the vacuum lines and modules. It really cleans up the engine bay and simplifies things, but only if you don't have emissions testing in your area.

 

ive found that a tiny bit of dielectirc(sp) grease helps old worn out rubber lines seal better and come off better the next time you want to remove them. try some of that when you check ur vac lines. or better yet remove the nest/**** altogether if you dont need it for emissions.

 

Ok, I checked all the hoses. No leaks, no loose hoses etc.
In addition to the chugging, the car has trouble idleing now. I bumped up the idle a bit but it doesn't help much. It will idle fine at 1000 RPM for a while, and then suddenly drop down to about 500, or die all together.
Any other ideas?

 

Have you tested your ignition system yet? If you don't have any vacuum leaks and the carb seems squared away, that'd be my next item on the checklist.

 

I remember your earlier post and I suggested that you check your jets, because that's what caused my problem. Based on that, I'd be looking for something that would make it run pig rich. Have you checked your plugs to see if they are black? That's a sure sign that it's running rich. I'm not good enough with carbs to know what else to look for that would cause it to run real rich...maybe someone else can chime in.

Rich

 

I found the link for the secondary disconnected. - that took care of the running rich problem, but didnt help with the chugging.
Ignition was ok when I checked it.