Yet another Yugo intruder: Specifically a carb question

I posted a brief introduction in the Discussion section.

of note: I'm an A-series British car guy, mostly, so I know SU carbs, but that's about it.

I have this 88 yugo with an engine rebuilt by the PO and the carburetor has all or nearly all of the smog stuff deleted. Well, anything that was controlled by a water temp thermostatic switch is now gone.

The carb seems to have an accelerator pump problem because it wants to die when the throttle is initially depressed. From reading, the first thing I should check is the accelerator pump.

But now, after driving it more this second day of ownership, it won't stay running unless I am giving it aggressive throttle. Ran great on the freeway, but then I came home and replaced some poorly capped off carb ports with better sealing caps.

Now, when letting off throttle it dies out. I've had to bump start it while still rolling and braking into a corner.

I briefly saw that there may be a known problem with the jets coming unscrewed??

Perhaps someone can maybe link me to a diagram that tells what each port or connection is supposed to be for? Fiat/Yugo carbs for idiots?

Thanks

I have an 87 Yugo with a 1500 engine, T25 turbo and I am even blowing through the same Weber DFTA carb which has been re-jetted.

I stripped everything smog related off the carb and capped off all the vacuum ports. It runs just fine without all that stuff connected. With the exception of the fuel vent port being connected to the carb bonnet to equalize the pressure in the fuel bowl under boost.

It sounds like one of two things. Either the idle jet is clogged or there is a massive vacuum leak somewhere. Possibly the gasket between the carb and intake manifold.

From what I've had happen to me, whenever an engine won't idle but only full throttle, typically means there is a vacuum leak somewhere between the carb and engine. I had this happen with a GM 454 big block. I used the gasket/isolator that came with the rebuild kit and afterwards it would not idle but would if I held the throttle wide open. So I used the old one and then it started up and ran.

On 128s, my experience with the Weber DATR and DMTR carbs is that the jets clog pretty easily. Removing them, blowing them out, and reinstalling usually does the trick on my cars. But those all have good baseline tunes. The carbs also feature an idle solenoid that will prevent running at idle if its unplugged or not functional. To tag onto the good points about vacuum that have already been made, some people tighten the carb mounting studs/nuts way too much and manage to warp the carb base plate, causing a vacuum leak after the throttle plate.

I think you're on to something about the idle solenoid. There's one solenoid plugged in on the back and the wire going into the potting material is suspect. AndI swore that when I purposefully touched it that It actually idled for a little bit when I started it up again.

Well, until it didn't any more.

So is that the idle solenoid?

There's another solenoid on the trans side of the carb that has a plug fitted to it but no wire feeding it.

Yeah, it's on the back of the carb (facing the firewall) and threads in right above the base. With the ignition in the ON position you should hear the solenoid click when you unplug it and plug it in again.

When I de-smogged my DFTA, I sawed the plunger off. It has to have power before it will work. I assume it blocks fuel flow to the idle circuit when it's not energized.

I think it's to prevent dieseling when running low octane fuel back in the 1980s.

I never had any problems with it being bypassed. I figured it was just another device to leave me stranded.

The DFTA seems to be some sort of emission US only version of the DMTR. It's not found on any cars outside the US.

The Ford Fiesta and Escort are the only other cars I know of that use this carburetor. I've seen NOS and factory rebuilt DFTAs on Ebay for less than $100. But may require rejetting if they are intended for a 1.6 liter Escort.

Spank... what Courtney and Turbo said, AND...

It would be BEST to pull the carb and disassemble it, and clean it properly in a carb acid bath.

Clearing out the tubes and rods will only be a temporary fix, GUARANTEED!

Secondly, make sure the fuel pump is pumping generous amounts of fuel into a cup. Install a new clear plastic fuel filter so you can see flow, and best to replace all old fabric laced fuel lines. Today's modern fuels disintegrate them and gook and particles get into the carb AFTER the filter. Same for the road draft tube (Crankcase Vent) tossing stuff down the throat of the carb.

As for the idle solenoid... once you get this car running right and cool it will become unnecessary. Pull it and plug it now if ya want... One less item to cause you trouble.

Lastly... all that 3 way thermo-valve did was prevent the carb secondary from operating, your dizzy from advancing and opening the EGR valve. I may have that messed up a bit but the principle is the same. Once the engine is warm, all devices will operate like any normal engine save the EGR. Usually the 3 way valve gets clogged so NOTHING works and BTW, you smog test a car when it is warm. See what I'm leading up to?

I'm open between 9 and 9 if ya wanna give me a shout. 661-268-7275



Take lots of fotos also!

HTH.