Specs:
Fresh Swap. 98' Vortec 350 from ck1500 swapped into a 92' original v6 car. Using stock in tank pump,Mallory return style regulator set at 6 psi to 600 cfm edelbrock performer electric choke carb.

Problem:
I can't keep the car running! I can crank her up, but it dies shortly after, can tell it's coming because motor drops rpm slightly just before it flat out dies. Can only keep it running for between 20-40 seconds by tickling the gas but it does eventually die regardless of how much I try and keep her going. While I'm tickling the gas the rpm is fluctuating between 2000rpm and 2500rpm and if I let off the gas the car will try to idle at about 1800rpm but fall on it's face in less than 10 seconds.

The carb is brand new, not rebuilt or used. I have a constant 6psi of fuel pressure. Fuel filter is clean. Plenty of fuel is reaching the carb. I haven't adjusted anything on the carb other than turning the idle screw down to up the idle to try and keep it running so I could tune, and have the idle air bleed screws (think that's what they're called) turned out 4.5 HALF turns.

Can anyone help? I'm stumped!

 

Make sure it's not flooding - leaking gas down the bores.
Pull the plugs out to see if they are black with soot -fouled.
Your plugs may have already gotten fouled so they may need replaced.
With good plugs in, pull the fuse to the fuel pump and start the car. With no fuel pressure it will not flood. It would just run normally until the bowls emptied.
Double check your initial timing.

 

I don't believe it is flooding. The pump is running the entire time but it can be restarted a couple seconds after it dies. Pulled the plugs and they're fine. Timing is not spot on, I was unable to turn the motor to get it to TDC so had to bump it with the starter until it was close and went from there. Which brought me to where I am now, unable to keep it running to get a timing light on it

 

I don't know if this will help any. As the problem was mainly in fords but it might be something to look into.

We were having a similar problem with three of my mom's cars. They would start and run fine for a few seconds and then BAM die. No warning. No nothing. I actually drove one of the Fords for the day and it did this to me 4 times in a 1 mile stretch. Just flatout die. The problem was a bad Ignition Module.

Now I don't know if GMC had the same thing. but you might check into the Ignition coil. Distributer, Cap, rotor, Hall effect Sensor. Spark Plug Resistance. Make sure your Spark plugs are gapped right and the right plugs for your car. Also, Check the Exhuast. Have someone start the car and place something between you and the tailpipe and hold it against the tail pipe. If your hand doesn't get pushed away you could have a clog that's fouling things up. Jsut some of my expereinces.

 

Just advance the distributor a little when you have it running until it doesn't die. If it's a timing issue, it will run if you give it a little more advance, which will let you set the timing.

 

It ran for a while longer after advancing the timing a bit, but it still dies

 

did you put an oil pressure switch in...thats probably your problem since it was mine, and it did the same thing. get a switch and install it right above the oil filter, and get the wires from the v6 harness for the switch and wire it to the new sensor. this tells the car to keep the fuel sender on. you can buy it at auto zone for 5bux or w/e

 

Have you checked all the vacume lines i just went through this with a camaro that i did a swap from cfi to carb it would start and die start and die it was a vacum leak that i thought i had fixed. after that the car started right up and just purrs.

hopoe this helps
steven