I have a problem I have been chasing for years. If I remember correctly, it happens on warm days, but that might have nothing to do with it.

1986 Trans Am with the original 305 carb. Around 30k original miles.

Yesterday coming home from work is a prime example of my issue. I drove the 57 miles there in 65 degree weather with no problem. On the way home, it was 88 degrees. The car stalled twice on the highway. I can be driving along just fine and all of a sudden the car acts like I ran out of gas. It just loses power and dies. If I sit at the side of the road with the hood up for about 20 minutes it will start back up. Most of the time it will get me home from where I am. Yesterday it stalled out on me twice. I carry a 1 gallon gas can in the hatch just in case, because my gas gauge always reads full (another issue for another thread). So, if I pop the air cleaner lid and pour some gas into the carb it all boils away quickly. I do that a couple of times and it seems to cool the carb enough that I an get it started and drive away. Might have nothing to do with it. It's not always on the highway, either. I could be tooling along in city traffic and it will suddenly stall while driving.

Some time ago I changed the fuel pump because the car wouldn't start. I knew I had gas in it because I filled the car up the previous week and barely drove it. Well, that turned out to be a case of having no gas. I dropped the fuel pump inlet hose into a gas can and it ran fine. Put some gas in the tank and it started then drove to the gas station where I put about 15 gallons in. A mystery. I thought maybe someone stole gas from me and a put a locking cap on the car. So, new gas cap. In fact, I have tried several caps thinking I had a venting or pressure problem. It still happens.

In the course of doing other things, I put a reman carb on, full tune-up including new coil and ignition module and a replacement ECM. The car runs great! I can feel all 165 hp . There seems to be no warning when it stalls.

Vapor lock, maybe? On the highway the car runs cool according to the temp gauge. But I bought a braided steel fuel line from Jeg's and some AN6 fittings and routed the fuel line away from the block. When I pulled off the old pump to carb line I saw there was a bad kink in it. Was that the problem? Nope. I noticed when I stalled that the braided line was hot to the touch. Not scorching, but hotter than I thought it should be. I then added a Moroso phenolic 1/2 carb spacer (yes, I had to dremel the secondary openings) and wrapped the braided fuel line with some Design Engineering Heat Sheath. I figured that would have to do it, but no. Stalled twice on the way home.

Maybe it is the fuel pump getting hot? It is attached to the block with a regular gasket, and I did take off those manifold heat shields when I did the tune-up, but wouldn't constantly circulating gas in the pump keep it cool, and wouldn't it happen all the time if it was the pump?

I bought the car with 24K miles on it from a guy who got MS and couldn't drive, so the car sat in his garage for 10 years. I have been replacing wear items as we go and the radiator flush was an adventure. I can't imagine the steel lines going back to the tank are having an issue, but I am grasping at straws now. I'm getting to the point where I don't want to drive it any distance.

I'm thinking about using some compressed air to see if the return line to the tank is clogged somehow. After that, I am at a loss. Like I said, I'm grasping at straws. I even hooked up a switch to my electric fan to make it run whenever the key is on so I had airflow in the engine compartment regardless of engine temp. That did nothing useful, and my car rarely ever hits the 220 mark on the temp gauge. I almost never throw original parts away, so I am going to look for those heat shields. They really don't look like they would make much of a difference, but I could be wrong. I also thought about heat wrapping the exhaust manifolds, but that doesn't look like much fun.

Any thoughts? Thanks in advance.

 

You are chasing this as a loss of fuel problem, which it may well be. But don't rule out loss of spark. The coil and ICM commonly cause intermittent stalling issues related to heat.

I would try to induce the problem and then test for spark, just to rule that out.

 

Back when many cars on the road had carburetors the fuel was formulated differently to prevent boiling and evaporating out of the fuel bowl vents. Modern reformulated gasoline has nothing to prevent this anymore. You just look at it and it will boil and evaporate.

The Quadrajet carburetors have several disadvantages compared to other carburetors when running on today's fuels.

They have a very small fuel bowl with a large float. So there ain't much fuel in there to start with.

The fuel bowl is centrally located inside the carburetor instead of on the ends or sides. It can't keep the fuel in the bowl cool because because the bowl has no sides exposed to airflow.

I have some ideas but I'm going out cruising with my buddy in his Grand National. LoL it will be fun because the AC ain't working. I'll add more when I get back later on.

 

I wondered about spark. I have one of those little light-up testers. I'll hook it from the cap to a plug wire and see if it lights up. The only way to test it is to take it on a long drive in the heat and wait for it to stall. I'll pack a cooler full of ice and Coke Zero.

I'm also wondering if the stock drop base air cleaner is holding heat against the carb. Not that I have a remedy handy for that. I could drop an aftermarket air cleaner on it and aim the snorkel from the stock intake to point at the carb so it gets outside air blown directly on it. That sounds so gimp, though!

 

And now I'm also wondering if I put enough thermal paste on when I changed the ICM. That's a pretty easy check.

 

Nothing about the ICM changes, one way or the other, when pouring fuel into the carb.

I'm getting tired of answering this question. Comes up in different forms ALL THE TIME.

Problem is, the fuel going into the carb, is getting HOT. It's under pressure when it's in the fuel line; then when it passes through the needle & seat, and reaches the fuel bowl, it's at atmospheric pressure. EXACTLY the same thing as leaving a Coke out in the sun, shaking it up, and popping off the top; then wondering why it SPEWS. Well, duhhhh...

Most of the heat is transferred into the fuel in the fuel pump, which in turn is heated by THE BLOCK. Try one of these https://www.summitracing.com/parts/ctr-85-000 I know it'll be painful, require a 2nd mortgage and all that, butt in the end, either ya wanna fix yer car or ya don't.

Of course, make sure your fuel pump has the return line like a stock one, and that it's hooked up. If it doesn't, take it off and throw it away, and put a stock one on, at the same time as you install that $$$$spendy$$$$ thing I linked you to. Sorry to tell you though, a stock fuel pump will probably require you to sell some non-critical body part, maybe a kidney, to afford it. https://www.autozone.com/external-en...002/340217_0_0 Shrinkflation these days...