Alright guys....this never ends. I thought I had my car's fuel issues solved but here is another one.

This car had a history of vapor lock which I finally thought I had nipped last summer with a new fuel pump/vapor separator/and return line. Up until yesterday the car has been running great and never a cut off.

Yesterday I went for a drive an I noticed the car started, ran for about 3-4 seconds, and then cut off. I did get it started (a little difficult) and drove it 15-20 miles no issues.

I drove it to the alignment shop this morning (3 miles) with no issues. I come back this afternoon to get the car and go to start it and it runs for 3-4 seconds and dies. Again with some difficulty I start it (pedal to the floor). I drive it with the alignment guy for 4-5 miles and park it to pay him.

I go to leave and the same thing. Car starts then dies. I get it started again and go to drive home. When I pull out on the road and go to take off, the car dies. I manage to get it started again and get back into the parking lot.

Here is what I found when I did some initial troubleshooting there:

- car won't start unless pedal is to the floor
- when car starts it runs and about 3-4 seconds later, fuel starts puking from the primary fuel bowl vent which kills the motor
- I tapped the fuel bowl and got the car re-started and checked the float level-just fine
- I then put the rear car tires against the curb so I could check the fuel pressure with the car in gear
- I put the car in reverse, turn on A/C, and open the throttle of the carb while I look at the fuel pressure gauge
- fuel pressure is great and car wants to pull itself over the curb so it's not cutting off under some load even after 10 minutes of trying this
- go to tray and leave again and once I go to start moving, the car dies again
- call tow truck and car starts up just fine and is good enough to drive itself on a flatbed (steep incline)
- my exhaust tips are carbon coated looking pig rich

Any ideas?? I don't think this is vapor lock as when I had the issue, the car wouldn't start once it died until it totally cooled off for 3-4 hours. I know this is the first truly HOT day here so it could be vapor lock but even after all this, the fuel line by the carb is only slightly warm and fuel bowls don't feel hot at all. Unlike so many of these cars, mine has no issues with overheating and was holding fine at 190* or so.

Do I just need to tear down the carb and make sure I don't have a stuck float or something? Carb is a Holley 4150.

Any ideas?

Inlet valve(s) are sticking open occasionally, had that issue with a Holley 2bbl.

So swap in new needles and seats then?

Wouldn't hurt to make sure the float doesn't have gas in it too. Never had it happen on a Holley, but I haven't had a Holley since they started making this crap gas either. But new needles and seats should be it, assuming they are adjusted properly as you said.

Correct, both of em. Lube the O rings on the needle/seat assys before installation. Gasket on both sides of the float hex locknut & I like to lube em as it will be turned on occaision. As said check the floats for saturation. Want a good high flow 10 micron filter right at the carb inlet. EDIT glassbead or new plugs/confirm your psi ain't excessive & you'll be back in business

I swapped in a new set of needle/seats and lubed the O-rings with some silicone grease. The bowls were pretty clean and the floats (brass) didn't appear to have any corrosion or pinholes that would let them fill up and sink. I took them out and shook them to see if they had any gas inside and nothing I could tell.

Both needle/seat looked ok from what I could tell. I did notice some sludge at the top of the primary needle/seat right at the top of the outside of the needle/seat housing (right under the adjustment nut). I am not sure if they had anything to do with it or not.

I got those in and set the float levels last night. I couldn't take the car out though as it was pouring rain here last night.

The one thing I am paranoid about now is vapor lock. I am praying that this was NOT vapor lock as I have nothing left I can do to combat it aside from going to a electric fuel pump which I have no desire to do. I don't see how this is vapor lock though as from my (quite extensive) experience, once the car vapor locks, there isn't much chance of restarting it until it is totally cool (3-4 hours). With this, the car can be restarted but dies when you start to move on it...the puking fuel out the bowl vents leads me to believe this was something with the needle/seat/floats and NOT vapor lock.

I will get a new set of plugs once I am confident that this is fixed. Thanks for all the help so far!

I cranked the car and it started right up and didn't cut off. I notice that the exhaust smells pig rich and it seems to idle a bit lower/rougher...especially when in gear.

I double-checked that the float levels are correct. Could the spark plugs be so fouled that they are causing this?

is there a fuel filter on the suction side of the pump?

Nope. All I have right now is the sock on the sender unit. I plan on adding a filter like RapidRobert suggested by the carburetor fuel inlet. I am just trying to find something that will fit and not get in the way of the distributor.

Update guys:

I swapped in new spark plugs and have put about 10 miles on the car with mixed freeway/city/stoplight driving.

No issues...seems to be running well. I even drove it around, got it totally warm, cut it off for 15 minutes, and then fired it back up and drove it across the street for a quick errand.

Hopefully it was just the needle/seat. I still can't quite tell exactly what was "wrong" with the old set...maybe the o-ring on it is slightly shriveled but the needle itself looks ok.