Odd issue with V6 not starting/dying.

[RICKDIZZLE]

Friends, I have had my 85 Cutlass Supreme with the 3.8 V6 for about 5 months now, I seem to have a random issue I can not track down. Every once in a while, I will start and drive the car, then park it, run back out and jump in to start it again and it just cranks...wont start? It almost acts like it is vapor locked? It will turn over and sounds good minus firing up. Then after 10-20 minutes, it will fire but will run at a very low idle for a moment and lots of black smoke comes from the exhaust, appears to be from fuel that loaded the carb as after 10 seconds it is running fine and zero smoke. This is an intermittent issue and last time it occurred, I checked and I am getting fuel so that's not the issue. Well the other day for the first time, I fired it up, drove around my block about 1/2 mile, flipped a u-turn and it just shut off? First time ever doing that! After about 30 mins of trying to start...nothing! Just cranking away! When it shut off, still had full electrical, no issue there. Got a tow strap and towed her home, tried to fire it up and boom, it started but ran like crud and smoked first few seconds. My thought is that it is an issue with spark. Would you guys agree or what else should I check?

 

[RICKDIZZLE]

Any ideas?

 

[RustRocket]

I honestly am no help to you, but I'm going to stay in this thread for future knowledge just in case I have a similar issue in the future

 

[MeanBuicks]

My Cutlass exhibited much the same symptoms as yours and I could never get a handle on it until I replaced the entire carburetor with an NOS unit I scored on eBay. I'd say either look for a known good used carb or go for a factory tested reman unit.

In the process of returning my Cutlass to the road after sitting for quite a few years I had already replaced the gas tank, sending unit, fuel pump, dist. cap and rotor and rebuilt the carb. It then acted like yours which was frustrating to say the least.

 

[ADentice]

My car does that sometimes where you drive for a little bit then after you shut it down all it wants to do is crank. Its almost like its not getting enough fuel or something. Im also using a stock carb on a 72 350. So part of it might just be the factory junk we're still using all these years later

 

[Bonnewagon]

Black smoke is fuel, so I'd look at the carb first. It appears you are flooding after warmup but it could be several things, choke, float, or needle/seat leakage. If you are familiar with carbs then I would start at the choke and work my way through it, and eventually just take it apart and rebuild it, but if not it would probably be best to get someone who knows what they are doing to troubleshoot. For example, a choke not opening fully would go unnoticed as you drive, but when you go to restart, the closed choke would cause what you are seeing. Rochester carbs have a choke unloader feature. That means when you press the gas pedal all the way to the floor, it forces the choke to open. If that starts the motor then you know the choke is at fault, and being electric, good contact is crucial. The factory grey connector breaks, and the choke coil housing tab is famous for rusting and failing. Pull the air cleaner off, warm up the motor, and verify the choke is opening fully.

 

[MeanBuicks]

Good advice. FWIW, my issue was fuel delivery, or lack of it. I was able to get it back running by either dribbling gas down the carb or, when out and about, by spraying judicious amounts of starting fluid at it while cranking.

This no-start/random stalling Russian roulette game got old fast though. When I swapped the carb, I was hesitant to leave the starter fluid behind but it hasn't been needed since. I just hate that I could never pin down exactly what was going on. I'm glad to have repaired it though as the car went from sitting, to antique-registered weekend-warrior to my current daily driver. It's nice that it's dependable.

 

[Bonnewagon]

Actually the carb is usually the last thing to be guilty. But when it is, it can drive you mad. I have had a few that just would not work right no matter what I did to them including total overhaul. Then there is the one that absolutely would not run right until I put it on another motor- and then it purred. But usually it is something minor like a bit of dirt caught in the needle/seat, or a fuel-logged float, or a blocked air bleed, or a balky choke. My experience is that the stock carb is the only one that belongs on a motor and occasionally it needs a good cleaning. In this case the black smoke is the giveaway- flooding.

 

[RICKDIZZLE]

Thank you all for the responses! I am going to do a full tune up, plugs, plug wires, fuel filter, distributor cap and rotor and use that as my starting point. Being that I bought the car only a few months ago...not sure how long ago this has all been done, so figure, use it like a check list and start here. Ill also have the carb cleaned and checked during the tune up and see what happens. Hope it fixes it...if not I will see if I can find a carb. I will keep you in the loop as to my findings, in hopes it will help others!

 

[CBARGE69]

The biggest problem with carbs is lack of maintenance. All carbs, no matter which brand, need periodic cleaning, lubing of linkages, and snugging up of screws and bolts. Like bonnewagon said dirt will cause a problem. In a carb, even a couple grains of sand will cause havoc. That being said, it sure sound like you have a problem with the choke system. After almost 30 years that little heat tensioned wind-up spring has got to be tired. One thing you may want to consider is the fuel type. In the past few years I am seeing more and more carbed cars come into the shop with ALL kinds of running problems caused by high ethanol content in todays fuel. Depending on where you live in the country depends on the amount allowed. Here in my neck of the woods, north central Indiana, 10% seems to be the max that is advertised at the pump. But I have tested the fuel in some customers cars and I can tell you that while 10% seems to be the average, I have seen some as high as 20-25% :shock: . And reading the data stream on some newer flex-fuel cars and trucks, being as high as 30-35% and the owners swear up and down they have only put regular gas in it. This is all just food for thought. Do what your doing fist, a complete tune-up, make sure the fuel system is working properly{that includes everything from the tank to the carb}. Be sure the timing is set right and the carb is adjusted EXACTLY as instructed in the shop manual. I wish you all the luck because I can tell you after 30 years in this business sometimes these little running problems make me want to