[caddor38]

Hey guys...I have another question that I was hoping to get some recommendations.

I recently finished my 71 firebird to Trans am build. I have test driven the cars 4 or 5 times and even took it to a car show and no issues. However, today I went to get gas and filled it up. Went back on the street and made a U-turn and the car turned off on me at the end of the U-turn. I tried to start it a couple of times and no dice and after about 1 to 2 minutes the car started and I headed home.
As you can surmise, I am now afraid of my car, laughs. I have an new fuel system, all new wiring, new motor. I was hoping someone could tell me what may force a car to shut off during a sharp turn? I wasn't pullin a smokey and the bandit type U turn, just nice and easy.

Thanks for any help.

[lucky1]

Float in carb could be set a bit low, when centrifugal force of upturn pushes fuel to the side of the bowl, the engine stalles from starvation.

Could be a poor or loose electrical connection too.

It can be frustrating sorting out a new build.

[steve25]

If it happens again then remove the air cleaner and look to see if the carb has flooded out which would mean your float is set too high.

[Joe's Garage]

If the engine was fully warmed up when you stopped for fuel, and presuming it took five minutes or so to add fuel, you may have experienced a bit of vapor lock.

Then, when the car sat for a few minutes, the heat dropped off enough to get some fuel to the carb and it started up.

Just a thought.

[johnta1]

I take it was cranking, but not starting?

[Sirrotica]

If the ambient air temperature was high, most likely would be boiling fuel in the fuel lines and carb. That would coincide with it starting back up after a few minutes. Pontiacs have always had vapor lock fuel boiling problems in hot weather, even before the EPA thought it would be a wonderful idea to blend ethanol with our gasolines. Considering you're from Florida, the possibility is pretty high.

Ethanol lowers the boiling point of gasoline, and if it boils inside of the fuel system, the needle and seat cannot control vaporized gasoline. It can go both ways by starving the engine because it's vaporized, and cause flooding because the float sinks in the partially vaporized fuel, both conditions will cause stalling.

In 1978 Pontiac was getting complaints about the same conditions causing stalling in hot weather, and started insulating the fuel lines with foam insulation on some of their cars.

If you have just installed the engine you might have inadvertently added to this problem with fuel lines too close to exhaust/heat source at some point. I can suggest you try insulating your lines if they're close to any heat source. The line that runs from the fuel pump to the carb crosses directly over the thermostat housing so it will pickup heat from the hottest portion of the cooling system by radiation. Go over the fuel system and see if you can see anyplace it could be picking up heat from, and insulate the lines, or fabricate some sort of heat shield to keep radiant heat from being absorbed into your fuel system.

Over may years I've seen owned, and raced many Pontiacs that were victims of excessive fuel heat, causing the problems you have described. While I made my living for decades working on Pontiacs, other brands of cars also suffer from fuel boiling on hot days, or after long runs on hot days. Keeping the fuel as cool as possible on carbureted cars helps keep stalling to a minimum.

This may, or may not be your problem, but looking the fuel system over, and trying to eliminate any excessive fuel heating sources costs virtually nothing, and can pay dividends.

[JUDGE3]

do the moroso cool cans really help this? always wondered. used to see them on a few street cars at the track years ago.

[caddor38]

Guys, thanks for all the responses. I have experienced vapor lock before and this did not seem to be vapor lock based on my past experience., but could be? The car was running around 210 degs. The car just died. when making the uturn! You know with vapor lock you can give it gas while its dying and it seems like the engine attempts to take the gas. I mean the engine died no response to the throttle at all. I was thinking electrical the way it died initially. The fuel lines are not close to the exhaust and run up the firewall to back of carb. I may go to a parking lot and re-create the issue by driving in tight circles after letting car get hot and sitting again. I will post the root cause if i find it.

[caddor38]

i addd a quick picture of the fuel line routing

[dataway]

Seems like if it was electrical it would have restarted immediately after the turn was done as the forces moving a wire or whatever would have ceased.

[johnta1]

Points or electronic ignition?
Electric or mechanical fuel pump?
Vented or non-vented gas tank?
Ground wires on engine to frame and chassis?
Have the starter off recently?
Check for loose connections on ignition wiring and battery wiring?

[sdbob]

Sock in gas tank plugged with debris?

[chuckies76ta]

Post # 11 mentioned. What distributor are you running? I believe the HEI has a pickup coil that can cause problems.

[Schurkey]

One U-turn, one stall. Tough to diagnose because we don't have a "pattern" of repeat issues.

If this is a random stall that just happened to occur during a U-turn, the solution is probably different from a stalling situation that happens with every U-turn.

Stalling on turns is generally a float/fuel level problem.

I fixed a stalling Ford decades ago. Engine died (instantly) every time the driver applied sudden throttle, or any throttle on left-hand turns. Always re-started. Engine was lifting under torque, pulling a wire harness taut, and breaking the connection inside the crappy-design "Bill Cosby--Quality is Job 1" Ford electrical connector. The harness was mis-routed, perhaps by the guy who'd rebuilt the carb (twice.)

[caddor38]

Hey guys, thanks for all your suggestions. I decided to get a cool carb technologies plate to begin with. I have significant hood clearance issues so the 1/4" plate was the most elevation I could use. I had to trim the plate in multiple locations because Holleys require and additional 1/4" spacer to clear the pumps, so with some high tech dremeling I made the plate work. To be honest I have not tested the vehicle as of yet. As soon as I run it around a bit and build up the temperature I will post the results and a picture of the plate for folks who may have a similar issue.

[caddor38]

Okay guys, I put a heat plate between the carb and the intake and problem still occurs. Engine temp was 215.. Just shuts off. I am able to crank it
as long as i hold accelerator to floor.

[steve25]

Your float level must be right on the edge of being too high and when the fuel heats up and expands to your turning of the car makes it spill out and the over rich condition stalls the motor out.

Also maybe the float is absorbing fuel .

[sdbob]

Have you replaced wiring under the hood,firewall?

[1969GPSJ]

Is your battery securely bolted down? Years ago a friend had a similar problem, and the battery (which at the time was not properly bolted down ) was flopping over and grounding out the positive on the body. It always took a minute or two to get it restarted.

[steve25]

I had a battery issue like that once where the hold down rotted out and learned a big lesson in grounding the motor to the body.

My battery had got thrown up on to the fender during a tight turn and by the grace of God in a parking lot and not on a highway.

Of course the motor shut off, but the only ground connection my motor had to the body was the transmission shift cable and that cough on fire since it was forced into conduction all the amperage the battery had!

Lesson learned, those factory braided cables that jump from the firewall to the rear of the heads are for sure needed!