Yugo problem -- runs poorly when hot

1988 Yugo -- this car has a Weber (a.k.a. Carter?) carburetor with all kinds of vacuum/emissions lines. In terms of Webers, it would be something very much like a DHTA. Among the other plumbing, it has an air pump, an EGR, and a cat.

The car starts well when cold ("cold" being 90-ish right now; the electric choke is never really engaged), idles very nicely, and runs great for a short time -- maybe 5 to 10 miles. Last night, I flogged it on a little loop through the countryside.

Coming back, it seemed like it was going to die if I let it drop to idle. No problem; I just blipped the throttle and heel-and-toed my way home. In the driveway, I let it drop back to idle, and it died after a few seconds. It wouldn't restart. (motor would spin, but not catch. There is fuel in the tank and to the carb)

At times -- though not last night -- it will seem to lose a cylinder intermittently while running, though putting the clutch in and blipping the throttle will usually clear it.

Any ideas what might be wrong?

I'm worried that all of the emissions plumbing might be acting up in some way; though simpler explanations/tests are appreciated.

Thanks Matt

Just pulling an idea out of the dark recesses of my memory, but they had problems with carb jets backing out. One of our techs bought a really nice Yugo that wouldn't really run for $100 because of that.

Another "Fiat" problem was the carb would get loose on the intake.

A 34 DATRA will spiff that engine bay right up. Dual 40's are even more fun.

I checked the jets earlier in the week. The jets for the secondary were a tiny bit loose -- less than 1/16 turn -- but tightening that didn't change the behavior.

(Actually, it may have changed the dropping-a-cylinder problem; I haven't had that since (though only two relatively brief test drives in that time), but the no-start when hot is still a problem.)

My wife pointed out this morning that the car has had some similar problems for a long time -- trouble starting when warm, particularly.

I've had the carb on and off several times over the years; never noticed it to be particularly loose when I took it off. But I will check the tightness of the carb tonight.

M

vapor lock?

seems like cold its fine but after you driving it it stops working? dunno though

One other symptom -- and this may just be my confusion on this carb, or it may actually say something about the problem here.

When I start the car cold, even if the electric choke is not engaged (this can happen fairly regularly in summer; ambient temps of 90+, a dark car in the sun... underhood temps get high enough to move the choke mechanism) -- valves fully open, fast idle screw not in contact with the cam -- the engine idles fast for a few minutes before settling back to the proper idle.

Matt

Or, along the lines of vapor lock, could it just be a problem with the evaporative loss system/charcoal cannister being clogged? Just kicking ideas around here.

My Fiat 124 had a breather cannister that didn't breathe; a non-start condition that was temporarily cured by loosening the gas cap and permanently fixed by replacing the breather.

Thanks, CarKid and DDavid.

Thanks, too, to Wonko.

I won't call you "the sane" because you seem to believe in magic spinning triangles

I wondered how long it would take for the jokes to come in.

The thing is, it runs brilliantly... for the first couple of miles.

My vote is on the coil getting hot and flaky...dang, now I'm hungry!

Bruce

Mmmmmm, pie.

Definitely need to check the coil once the car gets hot -- good catch.

Thanks M

just gimme the yugo and your problem is solved.

this is your other option instead of fixing it

I'll swap you for the Miata

Intake gasket leak maybe.

Treb wrote: I'll swap you for the Miata

had you told me this 24 hours ago i woulda. miata is sold and gone now

Last night, the plugs were wet & black.

Swapped in the coil from my DD, a new cap and rotor.

Plugs are now beautiful looking. (Actually, the plugs may even show it running a bit lean. Hard to tell exactly, but they're clean and dry, which is the important bit.)

Car runs great for ~15-20 miles, then falls flat on its face.

It will restart hot now, which is a huge improvement. But in the current state, after ~15-20 miles, it barely has the power to make it up the driveway.

I've looked at the vacuum system a little, and I see that there are thermo-switches on a coolant line that route vacuum to the egr and air injection systems. Oy. Now that makes my head hurt.

I need to check the manifold gasket leak idea; thanks for that suggestion.

Carkid, are you saying that you want my Yugo and have cash burning a hole in your pocket?

Thanks all, Matt

Well, I spent a few hours going through the vacuum systems. I have drawn a couple of pages of diagrams, tracing each line.

I found two broken lines -- hairline cracks -- and one broken fitting.

Took it for about 30 miles of test drives on Sunday night. Fun little car, once again.

Thanks to all for the help. Matt