Fuel problems

It could be fuel starvation if the electric pump is not pushing fuel toward the mechanical pump.
OP: you could check the fuel pump relay with a good ear. Turn on the igntion to on, listen for fuel pump relay to drop out in 8-10 seconds. That would indicate that the fuel system should be pressurized.
Inspect the oil pressure sending unit. Look at the connector for any signs of melted areas or oil leak. Located on front right side of engine. My book does not go back far enough to verify wire colors
Oldest model shows orange wire should have 12 volts DC with ignition in on position. The tan/white wire should come out of oil pressure sending unit and output from the relay to power fuel pump. If you have a elper you cn disconnect at oil pressure sending unit. connect volt meter to tan/white wire at connector. You should get 12 volts while relay is energized.
You can jumper between orange and tan?white wire to see if you can hear pump run.

JRscooby wrote:
Could the issue be clogged exhaust? Been sitting, could a nest be built in exhaust? That would let it start and idle, maybe rev for short burst. But the longer it runs build pressure in exhaust, have no vacuum to pull fuel in. Set for a bit, the pressure bleed, start and run again. Hook up vacuum gauge, hold a steady 1200-1500 RPM. If the gauge starts to drop, you have issue.

That's a really good thought. Especially true if the 02 sensor has aged out and the cat is plugged.

Could the issue be clogged exhaust? Been sitting, could a nest be built in exhaust? That would let it start and idle, maybe rev for short burst. But the longer it runs build pressure in exhaust, have no vacuum to pull fuel in. Set for a bit, the pressure bleed, start and run again. Hook up vacuum gauge, hold a steady 1200-1500 RPM. If the gauge starts to drop, you have issue.

enblethen wrote:
MDKMDK:
That is another good reason not to go to dealers. They do not have old school mechanics. If it cannot be diagnosed with a scan tool, they don't know what to do.

On my 1992 Lumina APV the dealership noted excessive brake pedal travel. So did I. they looked at it like 3 times and only minor, and temporary improvement.

Finally I put my vintage brain to work on the problem. and Next day hauled into Belle Tire (my tire place) and gave one special instruction to the consultant (Mic the drums) drove out with brakes like new.. of course the rear brake drums were new (front disc).

Yup. the Factory Trained Brake technician did not understand the older brake system. Not the only screw up they pulled.

enblethen wrote:
Yes! I am not saying not to take it to a shop, but not dealers.
Many after market shops can do a much better job then most dealers on older model vehicles.

X2. Sad but oh so true. Especially true when it comes to something older.

BTW, the fuel pump relay was a common failure item in that era. Most mechanics replace the relay as a precaution when they replace the pump.

I would also blow through the line and check for a restriction. Could be full of rust or the line could be damaged somewhere.
Also, ethanol based fuel will eat the rubber lines of that time period. You need to replace them all (you could be sucking air through a cracked line).

Assuming there are no mechanics at any dealerships that have seen or can work on a carburetor any more? That's a pretty broad assumption. You just don't like dealerships. OK, fine, but don't try to discourage others from trying them. I've had nothing but good luck with them. Like I said, they built it, and they can still service it. If they can't they'll tell you up front. Simple?
What have they done to you to make you dislike them?

MDKMDK:
That is another good reason not to go to dealers. They do not have old school mechanics. If it cannot be diagnosed with a scan tool, they don't know what to do.

Iraqvet05 wrote:
GM built it but when was the last time one of their service technicians have seen a carburetor? Sometimes it pays to seek older mechanics with experience.

Does GM discriminate against older mechanics? They don't have any at any of their locations? Scandalous!!! Most of the shops I've used have a couple of them in staff. They know there are still classic cars out there that have carbs.
None of the younger mechanics own older classic cars that they can't work on, because they've never seen a carburetor? C'mon, if they've ever pushed a lawn mower or worked on an RV generator, they've seen carburetors. They aren't as scarce as you imply.

GM built it but when was the last time one of their service technicians have seen a carburetor? Sometimes it pays to seek older mechanics with experience.

From experience. Try the fuel pressure regulator. Good luck