87 Buick V8 307 Stalling after driving 20-30 Minutes

[84 W40]

It sounds like a fuel problem or a EGR valve sticking in the open position in closed loop.
I would disconnect the vacuum line on the EGR and plug it and take it for a ride. Doing this is ruling out a bad EGR.

You said that the fuel filter was clean but did you replace it ? Reason I ask is that the car has 27k original miles and if it's the original filter, it could be on its way out. I will explain seen this happen twice, on my Hurst with the original fuel filter and at the dealership I worked at. There's a check valve built in the fuel filter on one end looks like a rubber plug. What that valve does in the closed position it prevents fuel from drain out of fuel bowl when the car is not running or sits for a few days. When the car is running the pressure from the fuel pump opens the valve and let's fuel in.
With the Hurst l was pulling it out my garage parked it and it was running, went in the house to grab my phone came outside and it wasn't running. Checked for spark that was good but no fuel to the carburetor. Ok bad fuel pump nope that was pumping fuel then l remembered about the car that I worked on at the dealership that had the bade check valve in the fuel filter. Removed the fuel filter pulled out that check valve, installed the fuel filter back in the carburetor and it started right up like nothing ever happened.
Not saying that your EGR valve and fuel filter are faulty, just ruling out the possibility. It will cost you nothing to disconnect a vacuum hose and removing the check valve on the fuel filter. Just make sure you install the the fuel filter with the check valve removed pointing towards the front of the engine.

 

[69hurstolds]

This is from an older post a few years back:

AC Delco GF471, aka GM p/n 5651803 fuel filter used in a SLEW of post 1976 engines, has a check valve in the end of it. Most of the 307 Olds engines used this filter. The idea behind the check valve was to prevent drainback and sucking out fuel from the filter line back to the tank.

They used this check valve filter in Corvettes too, and some of the 'vette guys were complaining that their engines were leaning out at higher RPMs in 2nd and 3rd gear. Turns out the valve was sticking and causing issues. Swapped filter to a non-check valve unit- problem solved. May work well in a stock engine, but for spirited and high speed driving, it's probably restrictive AF.

The AC Delco GF441, aka GM p/n 5650906 is the filter WITHOUT the check valve which can directly replace the GF471.

See that black rubber looking crap on the end of the filter? You can pull that out and there's the check valve. Little spring loaded thing.

 

[84 W40]

Wasn't just the vette guys complaining about it. If you were using that filter in a built motor with richer jets, that check valve was removed. We old bucks knew about that trick.

 

[78Delta88]

I think I might of mentioned that in another post. Every tune up I did back then, that got yanked out.

Also make sure the filter is in the correct direction. The metal cap goes into the carburetor. Lost count of the times I got a car with " just did a tune up..." And "now don't run..." Open the line and the filter was in backwards.

Did you ever put a vacuum gage on it? If vacuum is good and as load is applied needle runs toward zero... you have a plugged cat.

 

[Tore]

It sounds like a fuel problem or a EGR valve sticking in the open position in closed loop.
I would disconnect the vacuum line on the EGR and plug it and take it for a ride. Doing this is ruling out a bad EGR.

You said that the fuel filter was clean but did you replace it ? Reason I ask is that the car has 27k original miles and if it's the original filter, it could be on its way out. I will explain seen this happen twice, on my Hurst with the original fuel filter and at the dealership I worked at. There's a check valve built in the fuel filter on one end looks like a rubber plug. What that valve does in the closed position it prevents fuel from drain out of fuel bowl when the car is not running or sits for a few days. When the car is running the pressure from the fuel pump opens the valve and let's fuel in.
With the Hurst l was pulling it out my garage parked it and it was running, went in the house to grab my phone came outside and it wasn't running. Checked for spark that was good but no fuel to the carburetor. Ok bad fuel pump nope that was pumping fuel then l remembered about the car that I worked on at the dealership that had the bade check valve in the fuel filter. Removed the fuel filter pulled out that check valve, installed the fuel filter back in the carburetor and it started right up like nothing ever happened.
Not saying that your EGR valve and fuel filter are faulty, just ruling out the possibility. It will cost you nothing to disconnect a vacuum hose and removing the check valve on the fuel filter. Just make sure you install the the fuel filter with the check valve removed pointing towards the front of the engine.

Will try that this weekend.

 

[86 Salon]

When it stalls, remove the air cleaner lid and spray either in the carburetor. If it starts, it's fuel related. If it doesn't, its ignition related.

 

[Clone TIE Pilot]

Here is a video on how to perform a CCC System Performance Check.

 

[Clone TIE Pilot]

This is from an older post a few years back:

AC Delco GF471, aka GM p/n 5651803 fuel filter used in a SLEW of post 1976 engines, has a check valve in the end of it. Most of the 307 Olds engines used this filter. The idea behind the check valve was to prevent drainback and sucking out fuel from the filter line back to the tank.

They used this check valve filter in Corvettes too, and some of the 'vette guys were complaining that their engines were leaning out at higher RPMs in 2nd and 3rd gear. Turns out the valve was sticking and causing issues. Swapped filter to a non-check valve unit- problem solved. May work well in a stock engine, but for spirited and high speed driving, it's probably restrictive AF.

The AC Delco GF441, aka GM p/n 5650906 is the filter WITHOUT the check valve which can directly replace the GF471.

See that black rubber looking crap on the end of the filter? You can pull that out and there's the check valve. Little spring loaded thing.

Cliff Ruggles advises against using fuel filters with the check valves which you can easily ply out to turn them into a regular fuel filter.

 

[69hurstolds]

Cliff Ruggles advises against using fuel filters with the check valves which you can easily ply out to turn them into a regular fuel filter.

That's because Cliff liked to modify and extract more power from his engines, and needed to do it. I've used the Delco check valve versions in every stock G-body Olds engine I've ever had. No issues by keeping it.

I don't disagree with pulling it though if you want to. Or running a filter that didn't come with one if you already have it, as It's not absolutely needed. But normally, a stock 307 won't run out of fuel because you didn't pull the check valve out.

Just remember to pull the spring/valve section of the check valve out and NOT throw away the rubber seal part. Put that back in. Or you might as well not run a filter as fuel won't be forced to get filtered before entering the carb.

And for fun- most people are surprised to learn when you check your fuel filter for crud buildup, you have to look INSIDE of the end of the filter to see the trash. If things are doing their job, even a dirty AF filter should look relatively clean on the outside. This is because the fuel flows into the center of the filter first, then flows through to the outside of the filter media and enters the carb as filtered fuel from there. If the filter gets too clogged, the spring gives way and fuel can flow unfiltered around the filter. But that's just a fail safe.

To wit:

 

[Tore]

Alright plugged EGR vacuum line and took check valve out of fuel filter and still no luck. I did notice when it stalled out and trying to start right back up no fuel was coming from carb.